So, we're here to talk about securing the container supply chain with Notary. I'm Justin Cormac, I'm the CEO at Docker. I've been a Notary maintainer for many years and this is Toddy. Yeah, I'm Toddy Moaldanov. I'm a principal product manager at Microsoft. I am a maintainer for the last couple of months on Notary and I work on secure supply chain for containers for Microsoft and Microsoft customers. So, let's start with, you know, the end-to-end software supply chain, what we're, you know, what we're really trying to achieve. We've got, you know, developers, you know, building applications, pushing them to registries and what we're really seeing is that people are building up and trying to, you know, trying to add these components to build the secure supply chain on top of, you know, what started out as an ecosystem which sadly was built without any security properties at all. Yeah, so when you think about, like, when you have piece of software right, how do you ensure that it comes from, let's say, trusted source and how do you ensure that when it moves from one place to another place to third place to fourth place, actually the integrity of the software doesn't get compromised, right? That's what we are kind of thinking about the software secure supply chain and you need to ensure that actually it is trustable and not tampered with throughout the whole pipeline. And this example is specifically around, like, developer whether it's open source or inside the enterprise producing a piece of software, signing it, for example and making sure that actually it's signed during the build time and then it can go through the whole pipeline into the registry, get deployed to the Kubernetes cluster and you can add that mission on the Kubernetes cluster and ensure that, for example, the software is really produced by who you think it is and it's not changed. Meeting your policy requirements. So the Notary Project's really been driving innovation around a set of standards around the secure supply chain and we haven't been doing all these things like in the Notary Project and so we're doing them all over the ecosystem where it's most appropriate and where the standardization is best done. So we did, for example, there was the first question years ago it was like, where do we store signatures? How can we build this into the standards around OCI? What are the requirements? How are we going to do this? OCI had a bunch of limitations that made it kind of difficult so one of the big initiatives we did was work with the AuraS project around the artifact manifest and the referrers API. So the referrers API, one of the customer requirements that we got strongly from customers is that they want to be able to add things to containers and container images after they've been built to add supply chain information that wasn't known at build time and there's a lot of kind of thing to frame but it's like you've got immutable artifacts and if you change them they're a different artifact it's the kind of model that we built for containers and so the referrers API was built as a way to say well I've got this immutable artifact but I want to point to it with a referrer and add additional data to it that adds for example a later SBAR a detached signature and then if I want I can refer directly to the signature which points at the artifact or I can go to the artifact and ask the registry what are the things that people have added what's the additional data and so we prototype that we proposed it to OCI and that's part of the OCI 1.1 processor that's kind of shipping in OCI and you can now, this is gradually being supported in more in the registry ecosystem so there's work in distribution in order to have a reference implementation for that so that people can, we're in process of implementing a Docker hub and you've implemented it in ACR ACR so there's places you can test it now there's places where you can test out the work and make sure that it's providing the customer value and then the next stage is really helping people build stuff on top of that and working out the next stages and what the additional work is The most important part is actually using the referrers APIs and ensures that actually those artifacts are linked using kind of the digest which are kind of the shas and they are not linked by let's say the tag as for example some other products are trying to do because tag is mutable so you can very easily actually override the tag and say okay now actually I'll override the tag with different signatures which is my personal signature whether I'm trustable or not separate question Yep, so And I think a lot of what's come out of the process is there's a lot of different kinds of customer requirements around what the kind of workflows people want around signing and secure supply chain are there's still, there's a bill of materials which is becoming very important but then there's like Entei to ASA stations which people are really starting to become much more interested in adding to their images and so on so there's a whole ecosystem of pieces around images that we're building up standards for how to support them and still more work to do on standardization and helping people use OCI most effectively to do these things So really kind of emphasizing that notary is based on standards we're not trying to necessarily make the notary project a home of standards but there's a place where we collaborate on building those on building those standards so we've taken Seabourn for signing from IETF for example and JWS and things like that so we're taking existing existing standards from outside the ecosystem as well Right now we support both like JWS and COSI which is kind of the signing and encryption format for Seabourn the one reason actually we went with Seabourn is it's actually a very compact and binary format which means that signatures that are using COSI they can be also verified on a low power device if you have Raspberry Pi or even kind of smaller devices it doesn't need the computing power that for example to parse the JSON so you can save on energy when you use the COSI format Since last KubeCon this is kind of the progress that we made I don't know whether some of you attended last KubeCon they were actually just in one of my colleagues did demos but we are in RC stage right now so we had our first RC was in December we finalized the signature specification there and also the way that we can actually implement plugins to Notary so you can implement your own plugins in Notary if you want to for example support key votes that we do not support right now it's very easy to go and plug it in and use it in Notary One change that we had to do I don't know how much you are aware but there was significant kind of step back on the OCI side so in February we needed to do a change in the specification just to revert from using the artifact manifest to previous image manifest so that's on the spec side on the tool that we use for actually signing we call it Notation so we have almost four releases actually by end of this week or maybe next week we'll have RC4 and we are waiting on the security order to be completed in order to release actually the tool in the first version which will be kind of officially supported version for that but there are a lot of things that happen so we have remote signing trust store and trust policy so I'll demonstrate this in the demos later on you can see a bunch of features that actually you can use there but it's a full-fledged actually signing experience that you can use in Notary demo it's the demo time so I will need to switch to my actually duplicate the screens because it will be hard to for me to look with my back so let me just do that change we can jump in the demo so the first demo is really how the signing works so oops actually no that's the wrong demo the demo goals are not good today so sorry about that I need to re-run all these things that I thought I run right before we started but and it is failing last time if not I will run it from a video so okay sorry about that let me go to the video recording of that so we can save the time okay once again apologize for the demo goals what we are doing here is actually I'm setting up my environment so I have two images that I would like to sign one is the application image which is stored in the github container registry and the other one is the test image which is stored also in github container registry the flask sample is the one that actually I consider my application the net monitor is one which is the test image and now sign it with test key I have notation version 100RC4 which is a pre-release for RC4 RC4 will come as I said either later today Pacific time or on Monday the next thing is I have a plugin that I have configured AKV plugin that's Azure Key Vault that's where my actually remote key is stored so it's stored in very secure location I don't have the remote key on my machine so I will demonstrate how we can use this remote key to do the signing there are two tags for the images they both are called KubeCon demo v1 for both the flask sample and the net monitor image and I think that's the complete setup for my environment now what I will do is first I will create a test key on my machine and I will sign the test image with this test key so I will call the test key Wabbit Networks IO and there is a convenience command for that so if you want to actually test how the signing works you can use this convenience command it will create not only the test key but also will create the certificate that you can use to validate the signed image so if you lose the keys you will see that actually this is the network's key it can give you the keypad the certificate pad and the plugin name because the test key is associated with the core notation CLI it doesn't use any plugins it doesn't have a plugin name and of course if you lose the certificates you will see that there are also the certificates so this is the command that I can use to do the signing so as you can see I will use the test key to sign my test image and I will use the causing format for this signature so it's as simple as that you issue the command as always it gives you warning because I am trying to sign the tag and as we already mentioned the tag is mutable tag and what we do actually we sign the image with its digest not with the tag itself but it will give you this warning to say you should be signing tags you should be signing digest because that's the mutable part of the image and of course we have the notation list command that you can use to list the signatures there so if you do that you will see that the image which is the net monitor image with this particular digest has a notary signature and it gives you the digest of the signature the digest are linked so if you try to modify the signature then that will be actually tampering with the signature itself and it will invalidate the signature for that particular image so that is the first demo and having in mind that the demo gods are not working I will run the next one sorry again with the video so the next one is troubleshooting actually notation so when one of the things that actually we noticed when all the changes with OCI happens is really hard for kind of users and also our developers to go and figure out what's happening because different registries they provide different support for OCI so we need to troubleshoot a lot and either you debug it directly as a developer but sometimes people like me PMS we don't have all the gold environment setup and we needed to get some more information so I implemented a very detailed debugging capability so if you run it with for example the signing command with debug tag or switch you will get a very detailed actually output what is happening so as you can see we trace all the calls registry what we are sending what we are receiving back and of course at the end of the day I get an error from DHCR oops a little bit so I get an error and I can go and actually figure out eventually that error what that means so I can tell you at the moment because we investigated that error so many times some of the registries actually do not support deletions and as you can see the error here is really that delete failed the way that Github container registry is actually 1.0 compliant registry so they do not support yet the 1.1 reference types but there is a backwards compatibility with that the only problem is that as I mentioned many of the registries do not support the delete the way OCI works is that actually for backward compatibility we use manifest indexes and every time when you add a new signature you actually create a new manifest index and the tool tries to delete the old one and that's where actually it's failing right now that doesn't mean though that the new signature is not added and we will just see that actually this call succeeded so we have another command for helping you kind of investigate issues with notation which is inspect of the signatures so I can run notation aspect and this is my application image and if I run it I'll get a very detailed information about the signature itself so you can see it gives you not only the digest of the signature but also gives you additional information like the algorithm that is when it is signed, when it expires so if you had hit some for example errors like verification errors you can actually go and inspect it with that and again just to show that the second signing with Teschi succeeded so if I don't expect I can see that actually there are two signatures here there is the first one it's a little bit cut on the video and the second one the last demo that I will show is also the verification so let's go through the verification demo so the first thing that I will do is I will set up actually look at the trust or vocation so we have the concept of trust of course and trust policies in notation as you can see I have only one trustor which was for my test key and if you what I'm gonna do now is I will add additional certificate that I will trust for my application image so this additional certificate comes out of Key Vault as I mentioned we use Key Vault in this particular case where we store the keys and the certificate so I will just pull the certificate down store it locally and add it to my trustor this happening ok that is done so if you list the vocation you will see that's my certificate file and I am just adding this file to the trustor so this is a public certificate so there is nothing secret to it so you can go and pull it down and now if you list the trustor vocation you will see that I have two trust stores certificates that I trust one is Wabbit Networks which is my test certificate and the other one is the GHCR which came out of Key Vault now if I try to verify the image that will fail now the reason it fails is because I have not defined any trust policy I just pulled the keys but that doesn't mean that I trust this key for everything that I have in my registries so what we need to do is really to define a trust policy that will tell us what keys do we trust for which registries what that means is that you can actually provide different keys for different registries or different images that you want to deploy or run on your work route in this case I am just creating a trust policy for my application image I will not create a trust policy for the test image and the assumption is that I trust only the application image and the key on my production work route so if I do notation verify application image it succeeds if I do notation verify test image that will not succeed once again I should come on too fast I guess you are able to see the error anyway so those are the two demos apologize that we had to run them from the from the videos and let's get back to the slides so the next thing that we'll talk about is the notary security so notary we are actually we started first testing with notary back in December and we completed actually the first pass right now we have first tests that are continuously running on all the sub projects in notary there were two issues that were discovered one of those issues actually was filed as a security advisory and we have cv this issue was fixed in one of the RC versions the second issue was just a dependency issue and we updated the dependency and everything is good so there is a first report that you can go and read there is also a CNCF blog post describing that we would like to thank other logics for the first testing and all the great collaboration that we had with them we are also in the process as I mentioned to a security audit so we are not required to do that as an incubating project but it was something that actually we are really happy to do and we would like to do this on a regular basis not just once the security audit started in March we have the preliminary results from the security audit there was nothing severe discovered in notary as a security issue there will be report that will be published so the audit will be scheduled to complete by end of this month and the report will most probably show up in May we are just waiting for this security audit to complete and to have the report published in order to release the first version of Notation CLI on the community update so over the last year we had 52 contributors to the notary project 15 of those contributors were very active so they had more than 10 PRs in the project as we mentioned so since the last KubeCon we had 9 releases and we are just waiting for the security audit to get the first official release and supported release and that's for Notation we have also libraries which you can use in order to incorporate notary notary signing into tools like let's say Kiverno, Kiverno is doing that right now so they can verify notary signatures and we had 3 revisions on the signing specification and of course a website update what is next for Notation after 1.0 we will continue to add new capabilities like timestamp authorities, we will add certificate revocation we will add capabilities to verify more than one signature we are working on many usability improvements that is one thing that actually we will have significant improvements there and of course more debugging and verbose options there is one more demo that I will go through so one thing that we implemented is also signing so we have 6 minutes and we have few more things so what is the preference should I go through the demo or do you guys want to hear more what's coming from Notary and I will be happy to do a demo offline also shall we go through the slides and if we have time we can do it let's go through the slides so the one important thing for us in Notary is really the portability one of the things that we would like to make sure is that signatures that are created with Notary can be moved from registry to registry to registry they can be verified doesn't matter how many hops they had and the most important part is you can use it in an air gap environment of course you cannot rely on any communication outside this air gap environment like public endpoints for verification so everything that we create in Notary is with that in mind that customers are not actually freely open to go and communicate from their let's say Kubernetes clusters randomly to some internet endpoints we're also looking at with the standards around identity and verifiable identities so one of the important things around supply chain actions is like who did the action can you verify who it is can you trust who the person is supposed to be rather than dealing with typo squatting and things like that so we're also looking at working with the SCIT project which is an IETF project which is basically builds a transparency log and helps record identities and signatures so that's an ongoing IETF project that there's a lot of interest in as an external standard for supply chain security that we're working several people are working along with to work out how we should incorporate and build that with Notary there's a lot of interest which has been driving uptake of this around the additional metadata around supply chain so S-bombs, SBDX and other documents also in Toto attestations and more fine grained information about where things were built and so on like the testifiers that we're doing so we're really looking at how we can add all this kind of information to software in the container ecosystem how we can help people build all those things together and tools so you can have more fine grained controls about there's a specific issues with specific releases because you can trust the S-bomb work out what's in it work out whether you trust that particular release because you trust the dependencies or not and so on so this whole flow of information and the decisions based on real-time updated information that you have about what's going on is really important so that's another area again because I think we need more standards we're looking at we've done some prototyping around in Toto attestations from Docker build but we're looking at again putting that through the standard process now we've started prototyping it we've also just started we're doing some internal prototyping work but we've decided to go forward with a project for storing tough directly in the registry at Docker so that we're going to propose this as a new sub-project of NATURY so this is to directly store tough repository metadata directly in registry one of the initial issues we had with NATURY v1 was it stored in a separate database and part of the original plan was like how do we migrate everything out of these sort of sidecars that are not part of ACI and are separate and put them internally tough provides lots of advantages that we kind of don't have without that ability to distribute and rotate keys and delegate different people for different targets and sign the individual tags so this is all part of the fact that we see NATURY projects as a home for a set of standards around supply chain security that you can put together and build all the different things that people are asking for in this space we are right on time actually those are a couple of other sessions that unfortunately they are already passed but you can go and watch the recording so we had a vulnerability management session where we demonstrated together with 3V how you can manage vulnerabilities sign them, verify them and also use Kiverno to when actually deploy some work-outs on Kubernetes you can verify that let's say the SBOM or the image is signed that the vulnerability doesn't have high severity vulnerabilities of course Kiverno has a session that they also talk about NATURY there and there was another session with Ratify and Gatekeeper kind of using the same approach we don't have time for the last demo the last demo is actually how you can sign local artifacts so you don't need to have the image or the SBOM in the registry before signing it which is important for certain scenarios so if somebody is interested I'll be happy to run it like after the session or you will find it linked from the slides and you can watch it yourself. Thank you very much


Hi people, welcome to my channel, I am Arpita Karwa and in this video I am going to talk about the most frightening literary theory which scares almost every literature student that is Structuralism. Now I know that all of you are afraid of Structuralism because you have not yet understood what the theory is all about. You have not understood the basic assumptions and the basic principles of Structuralism. In this video my effort is to demystify Structuralism in such a way that it becomes really easy and simple for you to digest. And I am pretty sure that by the end of the video you are going to fall in love with Structuralism just like I have. So let's begin. Now first let's understand what is Structuralism. Now in order to understand Structuralism it is important to understand what is a structure. A structure in simple terms means order or arrangement and everything has a structure. If you look at the solar system then solar system follows a structure. There are planets, planets have continents, continents have countries, countries have states and states have cities. So there is a proper structure which is followed. Now you might think that okay this is scientific but what about Structuralism in literature? Do we have structures? If you are aware of Aristotle and his great work Poetics you must have read the structure of tragedy talked about by Aristotle in Poetics. So Structuralism is not a new theory. It existed way before we were even born. It existed during the time of ancient Greece when Aristotle for the first time talked about structure of tragedy. But this movement began somewhere around 1920s. Now in order to understand this movement let's divide history in two parts pre-1920s and post-1920s. Let's understand what was the difference in ideology. When it comes to literature before 1920s people used to look at a literary piece like a poem or a drama or a novel as a work. Now what do you mean by work? Work is something which is a physical object like a book and it was written by somebody. Now it is a closed ended thing. You cannot do anything about it. If a writer like John Dunn has written a poem that's a work. It was considered as a work before 1920s and it was closed ended. There was nothing that can be changed because a poem was written. You need to understand it by using social and cultural context and you need to devise meaning out of it. You cannot change it. On the other hand after 1920 the same literary piece like a poem, novel or a play was looked at from a different angle. It was no longer considered a work. It was now considered a text. Now what is a text? Text is a linguistic construct. Just like work is a physical object similarly text is a linguistic construct. And people believe that it's open ended. It's open to interpretation. If you understand the language that is written on the page you can have various interpretation. And that is what we in structuralism know as hermonotics of interpretation. Hermonotics of interpretation means various interpretation that you can get out by analyzing the linguistic construct. By understanding the language you can know a lot about the text. And it is now open ended. It is open to interpretation. Unlike work which is closed ended. A author has written and we can now understand what John Dunn was saying about his beloved. But now if you look at the same poem in the structuralist light you will find that it is open to interpretation. I might devise a lot of meaning on a very different meaning from what John Dunn intended it to be. John Dunn intended the sonnet to be a love sonnet. Now if I look at the language I might find post colonial references from it. And I might look at it from post structuralist or post colonial point of view. So you can see how I can understand the text even better by using structuralism which says that a text is a linguistic construct. Language is the main base of the text and by understanding language by interpreting language you can develop a lot of meaning from the text. It is independent of the author. Author has no right over the text now. You have the text and you can interpret it in whatever way. Author might have written it from one angle but it is now your text. It is open ended. It is free of interpretation. Now that we have understood what structuralism is all about it's time for me to introduce you to the great master of structuralism who is now known as the father of modern linguistics. So we have with us today Ferdinand Desashore and the next person we are going to talk about in this video is Mr. Ferdinand Desashore who is not only father of modern linguistics but who is also a great scholar of Sanskrit. So you will be surprised to know that Ferdinand Desashore was a great scholar of Sanskrit. He actually did his PhD in Sanskrit. And because of his understanding of Sanskrit and his understanding of works of Patanjali, Vratri Hari, Panini he was able to understand what is language. The first important principle of structuralism which he gave after understanding Sanskrit language is the concept of episteme. Now what is episteme? According to Ferdinand Desashore episteme means unit of knowledge is construct of language. Let me make it a bit simpler. He says that in order to learn anything in order to gain knowledge you need to know language. You cannot gain knowledge in this entire world if you don't have basic understanding of language. In other words he also says that linguistic determinism is the key. Now what is linguistic determinism? Linguistic determinism basically says that language determines thought. Think about it. Whatever you think, use it without language. Can you think anything in your mind without using any language be it Hindi, English, Tamil, Telugu, Bengali? No. Look at it. It is such a beautiful thing. What we discovered in structuralism is that you cannot learn anything or you cannot even think without the use of language. So language is the most essential element. Even if you look at a child he learns new things only by learning language. His concept of father comes by knowing that there is a man who has all these qualities and he is known as father. And that is how he can associate things and he can learn who father is. He can actually not learn about father if he doesn't have a word for it. So episteme says that in order to know something unit of knowledge is a construct of language. The next important principle of structuralism is that language has a structure. Let me give you a very simple example. Think about any word in English literature, English language which begins and is followed by three consecutive consonant sounds. Any word in English language which begins and is followed by three consecutive consonant sounds. Can you think it? I can give you examples. Strive, straight, scream. Look at these words. You would not be able to find any word which doesn't begin with S and still is followed by three consecutive consonant sounds. So you can find a structure. The first letter of any word having three consecutive consonant sound would begin with S. Then second letter would either be L or it can be two other consonants and then the third letter would be L or R. So you can see that there is a structure. First letter would be S. Second can be either of the three. Third can be L or R. And if this structure is followed then you can make n number of words having three consecutive consonant sounds. So you can see language has a structure. This is what structuralism says. The first principle is that language is most important thing. Language is essential for thinking. It is essential for gaining knowledge. Second principle is language has a structure. So this man Ferdinand Sashor made a huge contribution in the field of structuralism. And you will be amazed to know that he did not even write a single book in his lifetime. So then you might wonder that how do we know about his theories and his ideas? It is through the notes of his students. He was a lecturer and he used to teach in college. Now while he used to teach in college his students used to write down here. And those notes were published later in a form of book which was known as course in general linguistics. Now you need to also understand the fact that it is not just Ferdinand Sashor who made a huge contribution in a field of structuralism. There are a lot of other readers like Roland Barth and we have Vladimir Prop. Vladimir Prop has written this amazing work called Morphology of Folktale. Whereas Roland Barth is the one who is behind the concept of death of the author. Now we are going to look at all these texts in detail all these theorists in detail in our online course. Since this is a crash course I would just give you the major ideas. But then there are a lot of other things which are important from that point of view which I cover in detail in my online course. You can go to my website arpitaakarwa.com and check out the list of writers and theorists which I teach in my online course. If you really like the list you can join the course and avail 800 audio lectures, 200 PDFs and 3000 mock test questions. Coming back to Ferdinand Sashor, Ferdinand Sashor gave four major theories in the field of structuralism. The first one is sign and it's signifier and signified. So sign was divided by Ferdinand Sashor in two parts, signifier signified. The second concept was of Lang and Perol. Third concept was of signmatic and paradigmatic. And the fourth concept was of dichotomy and synchrotomy. So these were the four major concepts given by Ferdinand Sashor. And I'm going to discuss the first major concept that is sign and the division of signifier signified in this particular lecture. Ferdinand Sashor gave this beautiful concept of sign. What is sign? Sign is any word that you might see in English language. Any unit of language is known as sign. Now according to Sashor this sign is divided into two parts, signifier and signified. And it is written in a form of denominator and numerator just like we used to write fractions and mathematics. Now according to Ferdinand Sashor any word that you encounter has got two parts. There's a signifier and there's a signified and there's a relation between both of them. For example, let's look at a word dog. Now signifier means the word or sound and signified means the mental concept which is related to the word.  Now the sign here is composed of two parts. The word dog rings different kind of mental concepts in all of you. That means there is no fixed meaning attached to the word. Signifier and signified are different. Signifier is the word and signified is the mental concept related to it. Now what is important here to understand is that according to Ferdinand Sashor signifier is more important than signified. That is why it is written at the top. How is signifier more important? If you remember in Aristotle's poetic, Aristotle talks about the term logos. Now according to Aristotle, logos is the ultimate truth. And in Indian philosophy we call it Shabd Brahm Hai. Now what do you mean by Shabd Brahm Hai? Shabd Brahm Hai means that Shabd word is the most important thing, most essential thing. So according to structuralist, signifier is more important than signified. Why? Because signifier doesn't change, but signified keeps on changing.  Whereas signified is the concept that comes in our mind when we speak the word awful. Now if you remember in the earlier time, awful did not have the same meaning like it has today. Today awful means something which is really bad. In the earlier time, awful meant something which is full of awe, full of respect. And that is why they used to use the term awful majesty of God. So awful word has remained same. In 1600 in 2019 the word awful is same, signifier is same, but signified has changed. Earlier awful meant something which is beautiful, which is commendable. Now awful means something which is ugly, which is not at all important. So you can see signifier remains constant, signified keeps on changing. Another important thing and concept given by Ferdinand Sashor is the arbitrariness of signifier and signified. According to Sashor, the meaning of the word is culturally constructed. I give you a very simple example. What do you mean by cham-cham? Those of you who know Hindi might say that cham-cham means servant of somebody who keeps on buttering someone. That means you are just a person who keeps on going behind that person, keeps on pacifying that person, keeps on buttering that person. But if you look at the word cham-cha, a person who is not from 21st century and who is from 20th century India might say cham-cha means pawn. So how can you say the word cham-cha and the concept of cham-cha that we have in our mind is fixed, is universal? No. Everything is culturally constructed. My idea of God, the word God might have a different mental concept for me and your idea of God might have a different mental concept of you. In my case, for me, God means the idol of Lord Krishna. For you, if you are a Muslim, Allah might be connected to the word God. If you are a Christian, then Jesus Christ would be connected to the word God. If you are not a believer of God, if you are an atheist, then in that case you might look at God as a word which denotes soul. So you can see how the same word can have different meanings for everybody. And that is what Sashor says to be the arbitrariness of sign, of language. There is no fixed connection between signifier and signified. And finally, the most important concept given by Ferdinand Sashor is the concept where he talks about binary opposite. According to him, we are able to understand a word by looking at the opposite, the binary of the word.  Darkness is where there is no light. So you can see how you define a word. You define a word by talking about what it is not, the exact opposite. So darkness is when there is no light. What is dog according to you? Dog is dog because it is not cat, it is not a mammal, it is not a rat, it is not a rabbit, it is not a lion. If an image is not a rabbit, not a cat, not a lion, not a giraffe, then it is dog. So how do you define dog by contrasting it to the other things which it is not? So according to Ferdinand Sashor, language is arbitrary because it is culturally constructed. Also meaning can be only understood by looking at the binary opposite. You can understand what is fatness when you say that this person is not thin. Then we can say that he is fat. Similarly you can say that a table is stable because it is not a chair, it is not a fan, it is not a tube light, it is not an air conditioner, it is not a refrigerator. That is why it is a chair or it is a table. So that's what is meant by binary opposite in terms of structuralism. There are a lot of other important structuralist thinkers and concepts which you must cover if you are preparing for UGC net English literature. So if you are looking for an in-detail course where you can find each and every concept and also you can find detailed discussions on previous year papers of all the questions on structuralism, then you can join our online course. The details are given on our website arpathakarwa.com. You can also find it linked with this I button out there. If you subscribe to the online course you will be getting somewhere around 15 hours of audio lecture on each of these literary theory wherein we discuss each literary theory in detail and we also analyze each and every question from these literary theories as in the previous year papers. Apart from that you can also follow us on all the social media platforms so that you are updated about the recent net notification and you also avail free go net quiz. If you have not yet subscribed to the YouTube channel it's time to do that because we are running this fantastic crash course series on literary theory and cultural studies which is going to help you a lot in the upcoming net exam. So if you want to get notified about the next video which we are going to post very soon then do subscribe to the channel and also click on the bell icon right next to it so that you are notified. With that note I take your leave. Thank you so much. Happy learning. Keep loving literature and stay tuned to arpathakarwa.com.


Up here in the front spot in the front half of the room So for those who can't hear me because my voice is not that great today It's the SSID that we're gonna connect to is just Suza not the Suza OS training That's across the hall, but just Suza and the password is open stack all one word lowercase Yeah, there we go. All right. Now. Let's try this again and see if this works Yeah, look at that first try That's right. It is Oz right Okay Surprise we have this many people here for the last session of the of the entire conference Great. This is gonna be great Yeah Yeah, because the conference is great not because it's over Although my wife will be very happy to see me this evening Hey, at least you get to see your wife. I got a plane right to go. All right All right. Good afternoon. I guess we don't have a clicker Everybody say cheese cheese Good choice All right. Thank you for coming to our little thing and while those lights are bright. Okay, let's Look at this side of the room not because I don't like you guys but because I'm not blinded when I look over here So today what we're gonna do is we're gonna do a little bit of service orchestration This is a very basic introduction to heat who here has actually worked with heat before and tried to do templates and stuff like that Okay, so those of you who how many of you were successful at doing so? Okay, a lot more. Okay, those of you who are in that boat You're probably not gonna get a whole lot out of this and I'll be upfront with you right there This is this is very basic just standing up instances creating basic resources and connecting them together You're more than welcome to stay and to do that I just wanted to let you know ahead of time so you didn't get into this and then realize that now I already know all this and and I could have spent spending my whole time going and getting tacos Tacos and beer and tequila Sure more tacos. All right, so by way of introduction. My name is Rick Ashford. I am a Senior technology strategist. I just made that up today. Not really. I stole my co-workers title because I thought it sounded good For Suza, I've been doing this for about coming up on eight years now With me here is Sean Rickard who is three years three years here at Suza all all doing the same thing Our jobs are to work with our customers to help them understand the technologies and everything that we do And so part of that is doing classes like this Sean is based out of Montreal. I'm actually based about 20 miles up the road here in in Round Rock So I'm welcome all of you to our wonderful city if you have any questions about where you want to go for dinner tonight I have lots of good suggestions for you Do not waste your time in Taco Bell or McDonald's or Wendy's or something like that.  All right, so All that kind of fun stuff out of the way. We're gonna do a very quick Brief overview of the I've just heat what it is All that kind of stuff as some of the history and then we'll get into a little bit of the syntax for the For creating stuff and then we're gonna dive right in from there into the actual lab work I'll give you a URL that you can use to pull down the materials to do the labs so He is all about deployment of services for being able to do some right Typically, you know, you're you know, you don't normally have just like a single Application on a single server that you're launching up one at a time Usually it's a series of things that need to be done in concert and in order to provide an overall service There's three different ways that I want to talk about that you can deploy services in cloud The easy way they're not quite as easy way and then the hard upfront but totally easier and then and way and there's some good news We're actually gonna be doing all three today Just some extent. Yeah Okay The very first one how the easy way. How do I deploy it? Just log into the dashboard click the button to launch an instance? I create your stuff. That's one of the beauties of open stacking cloud computing in general is that you can very quickly and easily go in and point and click your way to a functioning Environment and that's okay, you know as first for some people. That's the way to go. They don't need to learn other stuff. That's great but You know sometimes you need as I said that he is usually by you know The services are typically not just one thing you have multiple resources you need to do together Oftentimes you have to repeat it because you need different instances to do different tasks and as a result you want something that's a repeatable process So that you don't have people constantly misconfiguring their systems when they're supposed to be bringing them up So they're not quite as easy way. There's a wonderful API for for open stack use There's a lot to command line tools You can go through you can write your scripts and you can script out and essentially do manual installs But do it from a scripting standpoint and that takes a little bit of time and effort to get into it But once you do that, it's very easy to keep rerunning that script One of the downsides though is this is not terribly friendly to all your potential cloud users I don't know about you but I Spent a lot of time In my professional career working with people that did not care for a command line My own mother actually liked to come up command line better than my than my customers did That's cheating a little bit because my dad was a 40 year IBM or and it's been doing did Linux for like a long time but But most most of your user end users don't like the command line You know Bob in finance he needs to be able to run his application There's WordPress blog or whatever he does not care to log into a UNIX term a Linux terminal an issue of some sort of commands to execute a script Not gonna belabor that point anymore. So the heart up front but totally easier in the end way is he itself It takes a little bit of time to get used to it I'll be quite up front. It's it's very difficult to find good documentation that you understand in good examples There have been I'll get to you in just a second sir. There have been lots of People have done piecemeal tutorials here and there and as long as you use the specific technologies that they did in the specific way They did those work very well, but when you're trying to adapt stuff and get it to be And get to be customized to your needs there the there's a lot of work that still needs to be done It's a much better than it was I've been doing teaching this course now for this is Probably the third year third Second or third year that I've been doing this and the documentation has improved dramatically over that period of time So this is less true now than it was but but it is still a little bit difficult But once you get past that barrier and you get the understanding for it It makes it very quick and easy and you have a simple script a simple page You can tell people just load this into your into your into your Dashboard and and go and once you know we're not we're not integrating that here But when if you use morano or one of these application catalogs this that takes it one step further It becomes your your push button app store So you had a question here in the front These slides are not only going to be available But I'm going to give you the URL for my laptop if you're on there And it has all the materials for the class in their lab materials Some additional stuff that you can play with on your own time if you want to do for example, there's an auto scaling Template for a patchy that that you're more than welcome to run It has a KVM image for it Which is a downside because I don't have a KVM hypervisor up here So you're not gonna be able to do that here, but you're more than welcome to take it with you and do that And the slides will be in there as well Marketing would probably prefer if I export that as a PDF before I turn that over to you So I will I will create the PDF momentarily Yeah, dry mouth, where's my water go? It's around here somewhere It's where I don't know right here in the front of course I don't know if anybody else has fallen victim to the pollen here, but I definitely have so I apologize for my very raspy voice All right. Yeah, I was very seriously worried about what I was gonna be able to do this this morning Even as early as this morning. I was not really able to talk above a whisper But we're doing good now. Yay Okay, so heat it's been around since grizzly is when it was started being the incubator project So it's got a little bit of history now And then we here at Suza have been supporting it since the Havana release Once it kind of got out of the incubation period We felt like that that point it was ready to be able to be supported So just by way of reference that was in Suza opens that cloud 3.0 Where we just released our 6.0 version based off of Liberty a couple weeks ago a Couple weeks or a month ago month ago about a month ago. Yeah Okay, that's not belabulous so What is heat so a quarter if you go and Google the definition for the the project and stuff like that So the heat is a service to orchestrate multiple composite cloud for the application Whatever right that's not the most exciting thing to read through in the month So I rewrote that so he allows you to pre-define a set of compute network and storage requirements to provide a specific Service and you can deploy the whole thing automatically My plan was to actually have a pocket. That was supposed to be a woo going on right there And just didn't come out of my out of my throat That allows to have a bunch of confetti and when he said automatic I was gonna But yeah Thanks, I appreciate you not actually doing that Okay So why is it called heat? Heat makes clouds rise. I get it You're bringing up your services As far as open source project names goes that's actually not half bad You know trying to get to where neutron comes into a software to find networking is a little bit more difficult I'm sure somebody really thought it was obvious at some point, but even even before when it's called quantum it still wasn't readily obvious what it did So there's two different formats that that are available if you're going to program for heat and there's three reasons to use both of them The first one is that heat was designed to be fully compatible with the cloud formations service on Amazon AWS Benefit being then that you could use this template either on AWS or on your local open stack infrastructure And you would not have to rewrite it each time you would you would be able to use a common template between those and that Can save you a lot of time We're not going to actually do The AWS stuff today, but I did want you to know that it is there and it is something that you can use and if you are an Amazon user It can be it can be quite helpful for you Reduce your duplication of resources Then there the other methodology is the heat orchestration template I don't know why I keep looking over my shoulder this way when it's sitting right here in front of me But it's forced to have it So the the other one is the heat orchestration template or hot This is a YAML based template that In that's what we're going to be using for The exercises today who here is familiar with YAML just by wave shape. Oh, that's a good. Yeah So you guys already know mind your spaces. That's right mind your spacing That's I've over the the two three years. I've been doing this that it's like 99% of the questions that people have come Down to they indented two spaces instead of three or three instead of four or something like that Exciting okay, so getting back to weird open-source project names YAML stands for YAML Ain't a markup language because somebody wanted to be recursive And they're naming for them so you can see that it's a Structured via indentation right here So so spacing as Sean was just pointing out counts quite a bit in here because that's how it's kind of like Python and that That's how you delineate your control structures and whatnot If it helps anybody just think two four six eight. Who do we appreciate Sousa? I'm not following you on that one man Where that comes oh I say two spaces for space. Oh, okay. There we go Okay, I got you. Oh, that was clever Sure it was Okay All right, so so it's structured to be indentation your sequence items Argument be noted by a dash that means if you're gonna have multiple values assigned to something you're gonna have a dash then you'll have your input your key value pairs and Key value pairs within a map are separated by colon and that sounds not terribly intuitive, but It'll make more sense as you go through the exercises and get used to looking at once you get used to looking at YAML It's actually a very easy to read and it's It's much nicer than something it's much better than something like XML that's just gonna drive you crazy All right, so just to get an idea of what some we're gonna walk through a couple of things We're gonna do in the in the exercises the first thing is we're gonna do just our basic kind of a hello world thing where we're gonna use the the OS Nova server resource type to just launch up a single instance We're not gonna sign it any special networking. We're not gonna do anything special with it Just kind of bring it up see that it's there feel feel proud of our achievements And then we'll bring it down and go on to the next next little thing and please refer to the documentation That's on the the sir on the host not that slide because the the template name or the KVM image name has changed So fair warning on that. Oh, did you mess that up? Yeah, I Had Sean he was my beta tester this afternoon to make sure this stuff is all working and so yeah The slides are here just to kind of give them a view of the format not necessarily to be the reference for them Next thing you can do is once you have you know the ability to declare those resources You're oftentimes you're gonna want to have some sort of variable input from your users And now you can get five parameters, you know, it's standard programming type stuff. So you define in there You have You can define the the type of your parameter in this case. These are strings And you can give it a label if you want description in that the the heat engine when you go and load it up in the web interface We'll actually pull that out and give you nice pretty text boxes and all that kind of stuff for users to be able to put their stuff into it so Pretty easy to get yourself some Some parameters and then you can see down here in the resources That for example the key name is a get does I get parameter on it on the key name to be able to pull that in there? And you can use that as a reference Again, if you if you've done programming, this is fairly basic stuff Not everybody has done that though. So we do need to cover it a little bit You can do additional things beyond just doing the the parameters themselves You can Here Yeah, here we go the big thing here is it Down at the bottom of the the password you notice that there's a hidden colon true So if you're gonna have something that you do want to have, you know, there's little stars instead of showing up on there say root password or Your social security number for if you are stupid enough to put that into your into your application You can put the hidden colon true on there and and that will take care of it for you And now that the other thing in the top one is you can set defaults pretty straightforward You can also do restricting user input Because as everybody knows if you let users type in whatever they want the things that they type in will not make any sense But so ever I wish I thought I had a time to go and get that xkcd comic with the little bobby tables Do I remember that one? Yeah, okay good. That was a great one one now Like I tried sharing that with my friends on Facebook once a couple of years ago and it just Went over their head at 10,000 feet and climbing So I like having an audience like that where you can bring it up and people like this where you can bring it up and people understand it and I Thought I silenced my Google Hangouts, but apparently not so All right So yes allowed values so in the top one we're actually setting specific values In this case we're picking flavors of what we're gonna launch up for our instances to be what size Instances we're gonna launch up and you can see right here. We're restricting it to a specifics These are this one's gonna be restricting it to larger values In our case right here because we are doing these on these small laptops and there's a fair number of people in here I've actually limited you and there's only one flavor allowed, which is the M1 tiny Smalls it goes And then you can see also on the password section down here You can even go into allowed patterns if you know your regular expressions that means you're awesome and You can go in there and you can define out how you know the patterns if you need to have a certain number of spaces and characters or If you're gonna be the the password Nazi that makes you have a 20 character thing that rotates every two days and You can't have more than three repeating characters or something like that I'm not very happy with our corporate IT right now. They changed their password policies I had the same password for like six years and now I have to change it all the time So that's me complaining All right, so let's talk a little bit about the Docker pieces here who here is familiar with Docker I would hope that at this point if you've been at this conference all week long that you've at least heard the name Docker If you haven't that means you didn't pay attention to any of the keynotes And I can't really help you at that point So in the context of heat There's two different resource types that you can use to to talk egg to create Docker instances One is one that was contributed as an as a third-party plug-in By Docker Inc to be able to actually create Docker containers And then there's the traditional OS Nova server like we saw in the example I had earlier And we'll talk in just a second and about About that nice as soon as we get done with the presentation I'm gonna kill that hang out and figure out why it's still putting up notifications one One heads up if you are going to be doing doing Docker with your in your own setups at home Note that your glance image name must be the same as the the the name In if when the image is in Docker, right? If you do if you do a Docker images, it'll say like Sousa slash 12 sp1 or whatever your image name in Glance has to be the same as that name Otherwise, it'll start to launch up and then it'll stall out and doc will complain and Then everybody hates you So don't do that. Yeah, and also hats off to Cameron and and Al who have now been Basically yelling at the people on the hangout These are jerks So two of my co-workers are here in their front two rows and they're sit there They're the ones that are throwing up all the stuff up there. Thanks guys Oh Thanks. Yeah, go me See, you didn't know that you were coming over the comedy show today Yeah, all right. So doc the the one from doc greek. We're not going to be using this one today Because primarily for the for the last bullet point right there But basically what this one does is it tells tells you have to have a base image That you have sitting in your glance repository And you need to it will actually launch up that image as a standard VM And then it will do a doctor poll and pull your your Containers from a from a repository from a doctor repository over into that system and launch them up And they're all clustered there together nice and tidy on their own individual VM I'm not necessarily a big huge fan of this methodology Because to me it's a huge waste of resources the whole point of one of the whole points of Docker is that You know by using the layered file systems and overlapping and all that kind of stuff you can get a lot better performance Then you would if you were just Doing virtual machines if you're gonna throw the virtual machine in there you could kill that entire Point of doing that. I guess it means you don't have to launch multiple virtual machines, but still it is good though if you're in some sort of industry where there's some sort of compliance whether it's PCI or whether it's HIPAA or if you're doing Government work and you need to be Compatible with that. There are some there are times in there. They require strict separation of resources And that that would be a good reason. I would think to be able to do it this way.  I Don't want to lose my microphone. All right. The other one the OS Nova server This is really nice because Hey, this is the one uses a dedicated Docker compute node. So and that was sent to the Nova scheduler. It's just like any other hypervisor And it works the same Benefit here is you don't have that virtualization overhead. Especially if you have a lot of images that are based off of a single Base image you can get some really great Efficiency and your use of your resources and you can really pack in a lot of workloads Onto a onto a single single system Did I leave some out? Dedicated no overhead Look at that I got it all Seems like there's something else. Oh, the nice thing about this as well I didn't put this in the bullet points is that if you're using the OS Nova server Template types and you decide that you want to switch from Docker to something else or something to Docker You don't have to rewrite your heat templates If you're using the standard Stuff right here, then it makes it very easy to swap it out and that way you can experiment with different platform architectures And not have to worry about screwing up bring up your Rewriting your heat templates to to get there Okay, I just a couple resources And again, I'm not expecting anybody to write this down right now I am going to have these slides available on my on my laptop up here that you'll be able to download If we're able help for however many people are able to actually get on to my poor Access point there in the middle of the room. We'll see how this goes But there's there's these are two places where I found some good heat templates out there I was able to use as a basis for doing my stuff there at over the last couple of years. There's really been Expanding of the what's out there online and some of it is even marginally relevant. So yay All right So let's go ahead and do let's do this right? If anybody has questions while doing the the work just raise your hand. I'll come down and I'll help you out the best I can All right, so for those of you who were not in when we were talked about the SSID You want to be on the Susan network not the Susan OS training that of my colleague Ron Terry across the hall And he probably would not appreciate it if we're sucking up all of his bandwidth More importantly though, you would not be able to access any of the resources here Your horizon dashboard is going to be on at this IP address So for users what we're gonna do is we're gonna start here in the front row if once Cameron gets off of his phone Cameron, thank you We're gonna start saying numbers and going down and basically that number is going to be Part of your username. So if you're number one, you will be Austin one with the password of Austin We're super creative right here.  Let's start with you gentlemen right there. So one Two 15 All right, let's come back up here. This is 52 is the last back there Start back up here in the front row and hopefully we don't go past 99 because that's all I put in there What started 54, okay 54 Okay, once we go past 99 I'll Once we know how many it is I'll create additional users and spaces Okay, and that's my boss of the back of the year. He doesn't need to get on here Okay Okay, so we ended up at a hundred and five. What's that? Let me go ahead and so that was actually a sneaky way to find out exactly how many people we have here Super sneaky was that that the counting off that was a our way to find out how many people were actually attending the session And just so you guys know One of our colleagues I did a presentation with him and he made a really good point for for this session You can think of Rick as Wikipedia and you can think of me more Like a YouTube you're what more like a YouTube? No, but I'm pretty obnoxious so everybody go ahead and try to yep, you got a question over there The last slide can you bring up the last slide Rick, please and thank you So is anybody unable to connect to the Wi-Fi you can't log in okay I'm not sure what my I think I did a hundred and twenty IP addresses on that thing. So hopefully I Mean, it's a small little Apple airport thing so Last time I did this class. I had ten people Time before that I hadn't like 50 or 60 or so so I was not expecting a hundred which is it's great to have you here I'm just gonna take a second Is anybody else unable to log on to the console you can't log on Make sure they did it right the images are that the Docker image is already imported in there You should have you should have them available to you You should not need to go grab the Docker images the the KVM images that are in there You're welcome to grab them to to use in your own spare time later and use your kids with it The camera there's a couple of hands going up back there if you don't mind So there is a PDF on on that server there on the host that has the lab manual So feel free to pop that open and Conserve it what? I'm about to have a hundred and ten I've created the users and I've created the in the tenants, but the projects But I have I need to sign the rolls real quick and then and then they'll be ready to go Okay So for those who can't log in just give us a second we'll get that fixed up for you Okay So for first off for those of you who are over 99 you should be able to log in now with your with your credentials What's that? You don't you do not want to do copy paste Okay, so I purposely left it a little bit difficult like that So that forces you to interact with the text if you just go through and copy and paste Without really looking or reading it You'll go through the lab really quickly, which is great for you, but you don't actually learn anything. So so I'm Exactly But it teaches you so That's the whole point. Okay, so we have specific users that are having problems so a Couple of people have been asking me about this if you're if you get through the parsing of Of your yaml file and the actual creation fails. Don't worry about it. You can actually just move on We're not going to be going into the instances themselves. It's really just to see how the yaml file Sets up the the parameters Okay, I've gone through and I'm updating the quotas for everybody to give it a little bit more resources available to you However, be pleased be responsible If you have once you get done with an exercise terminate your stack don't sit there with multiple stacks open So we can leave resources available for other people Okay, I ran a script earlier The supposedly was going to put the key pair that you needed for it and in there into each of the tenants But apparently something is weird is happening And not everybody is having those I'm not sure how it would happen on part of them But not all for if you don't have the key pair in there just simply create a key pair Through the interface going through the access and security rules section and create a key pair You can give it the same name as what I had and just put some random text in there Or you can create your own and then just adapt your resources when you're putting them in there So for the people that it cannot log in that you're getting the refresh when you're trying to put in your username and password We're working on that right now. It should be fixed in the next couple minutes Yeah, it could also be related to your web browser So Just for those of you who are having trouble logging in The gentleman over here was using edge as his browser and that did not work once he switched to chrome He was fine so if you're using edge as your browser and you're having the The issue with with not being able to log in then try the try different browser So there was one question up here about whether this stuff was SUSE specific or whether this is just general All this is completely general. There's nothing SUSE specific about this So very quickly I had this question come up a couple of times So what you're deploying are actual docker images So the images that are that you are using are spinning up those docker containers and it's all running on a Docker rolled or Nova Docker in in crowbar So there is a bug that's in the the the lab on purpose So you will get there and we actually set it up there so you guys can can put it around and then try to fix it So it's a little bit of a hint. It's in the networking section of it So you'll get to it and if you have questions just let us know So we've had a couple people ask where's the docker and all of this Who here was wondering the same thing? Okay, so the point of the point here what I was trying to get across was that Remember they said there's the two different ways of doing it I prefer to do it this way where you're using the standard resources and it's just it everything You're doing is with docker containers It's just you're doing it using the standard resources the benefit to that being that it makes it much more portable From I deal with a lot of my customers are all very large enterprises that have multiple hypervisors and platforms and stuff like that and so by being able to use the common resources that makes it enables it so they Can shift it back and forth between them much easier Without having to rewrite every time which is why I decided to do it this way that and I feel like this is a much more Efficient re-use of resources if we were launching up VMs for everybody to do all this This system would have cratered even a lot faster than it did already


Hi, I'm Zor. Welcome to Unizor Education. Let's solve a few problems on kinematics. This is the second series of problems. And this is all part of the Physics 14 course of advanced physics for high school students and high school level students, I would say. It's all presented on Unizor.com. Thank you to watch the lecture from this website because it contains notes for every lecture. And for lecture as this one, for instance, where the problems are solved, I usually put the problems themselves, I state the problems and have an answer. So you can try to solve the problems yourself and check against the answer, which I definitely recommend you to do before you listen into this lecture. It's very important to think about the problems before you listen to a solution, right? All right, so let's go. Problem number one is you have two wheels with teeth and they are locked into each other, which means that this one rotates this way, this rotates this way. Now, I know the radiuses, r and r, and I know the angular velocity of one of them. What's my angular velocity of another one? Well, that's an easy thing because obviously you have learned, there is a concept of linear velocity of the point which is rotating, right? So linear velocity is basically the magnitude of the velocity vector, and it's the same for these, but since they are locked into each other, it's exactly the same as this. So linear velocity of points on the rim of this wheel and on the rim of this wheel exactly the same. So what is my linear velocity? Well, it's radius times angular velocity, as we know, right? Because whenever my rotation, whenever my vector, let's say, moves by a certain angle phi, then this is, the length of this arc is r times phi. And the speed, linear speed along this movement is basically a derivative of this, and the derivative of this is obviously omega because phi is equal to omega times time, right? Obviously we are assuming that rotation is uniform, which means omega is a constant. Alright, so basically we can find out our, let's say this is omega 1. So this is r times omega 1, right? Because this is linear speed of the point on this wheel and this is linear speed on the rim of this wheel, and that must be the same from which w1 is equal to r over r omega. So as we see, the angular velocities are inversely proportional to radiuses. The bigger the radius, the smaller angular velocity, it's slower. And the smaller radius, obviously, the rotation is faster. And that's how all the different machinery is working whenever we want to change the number of rotations, let's say, per second or whatever. Okay, next. Next I would like to know how fast I'm rotating around the Earth's axis. So basically we are talking about Earth. Now this is its axis. Now this is equator. Now let's assume that I am at certain latitude. Now latitude is an angle from the equator to the point where I am locating. Now I am basically circulating around this trajectory, right? So this is the radius of my circulation. Now what is this radius? If I know the latitude, phi, then obviously my radius is equal to, sorry, my radius is equal to radius of the Earth, which is this one, times which is this one as well. And this is r times cosine of my latitude. So if my latitude is given, then I can find out the radius on which I am circulating around the Earth. Now what's my angular velocity? Well angular velocity is one rotation in 24 hours, right? T, which is actually 2 phi over 24 in radians per hour. Now the radius of the Earth, I also know kilometers. So I know the radius, I know my latitude. Well let's say my latitude is 60 degree of north, let's say. 60 degree of north. Alright, so that's pretty much sufficient to find out my linear speed as I am circulating, because I know the radius, I know the angular speed omega. So it's radius times omega is equal to r cosine phi times 2 phi over 24. And that is my kilometers per hour. Now I have actually calculated this based on the numbers and the result is 837 kilometers per hour, which is pretty fast. So I am on the 60s parallel, rotating around the Earth. My speed of rotation, well relative to stars, let's say, is something comparable to an airplane. That's my speed. As I'm stanging, well right now it's even more because right now I'm in New York. New York is about 40 something degrees, so it's a little bit less than that, which means my radius is greater, so I mean even faster than this. Something like 1000 kilometers per hour. I'm moving right now around the Earth's axis. Now obviously I'm also moving with the Earth somewhere else around sun, but that's not my problem right now. Alright, so that's my movement around the Earth's axis. Now next problem is similar. So let's consider the same Earth. And at some parallel, I don't know which one, on the height of 10 kilometers, I'm in the plane. So this airplane is moving east to west. Now I'm noticing that sun stands still in my window. So I'm basically moving exactly the same as the sun from east to west. So I'm moving along this parallel. Let's say my speed is 900 kilometers per hour, which is the normal speed for the plane. Now my question is, where exactly am I as far as the parallel is concerned? What's my latitude? If sun stands still, if I'm basically moving around the Earth's axis, it's exactly the same angular speed as the sun. Because that's exactly what it means. If sun stands still in my window, it means I'm moving east to west with exactly the same angular velocity as the sun. So I'm making one full circle in 24 hours. Alright, so what's my angular velocity? Well, we know this is 2 pi over 24 hours, right? That's my angular velocity. Let's put it omega. Omega is equal to pi over 24. Now what I don't know, I don't know the radius because I don't know my latitude. That's what's necessary to do, to find out. Now, what exactly is this radius? Well, this radius is equal to r times cosine phi, where phi is my latitude, right? Now, I'm actually flying a little bit higher. I'm not on the surface of the Earth. I'm 10 kilometers higher than that. So let's say this is my radius around which I circulate. Basically, it doesn't really mean much because this is 6400. And relative to this, this is minuscule. So our height over the Earth is not really that important. But anyway, let's add it in. So this is my radius. This is my omega. This is my angular velocity, right? And that's my speed. And the speed is, again, no. So all I have to do is to find omega from this. Oh, no, sorry, omega is given. All I have to find is phi.  So all I have to do is to find cosine, which is a very easy equation, basically here, right? So finding cosine first, and then you do the arc cosine to find out the angle itself, which is the latitude. And I did make some calculations here, and the result is approximately 57 degrees latitude. Okay? Next. Okay, now we have a clock. And at 12 noon, both hands are vertical, and they point to 12. They coincide. The question is, when is the next time they will coincide? Now, obviously, it will be somewhere after one o'clock, right? Now, at one o'clock it will be this, and this is the hand for the hours, this is the hand for a minute, but a little bit after one o'clock, my minute will catch up with the hour, right? Okay, so how can we find out this time interval during which they will coincide again? Well, we do know their angular velocity. Our hand will make one circle in 12 hours, so it's 2 pi over 12 hours. My minute hand will have angular velocity 2 pi in one hour, right? Which is 2 pi. So I have angular velocities. Now, if I have an angular velocity, I obviously have their linear velocity, r times omega h, and the minute is equal to r times omega minute, where r is the radius of the clock. Unknown, but it's completely irrelevant, because the length of the hands is irrelevant. All I'm interested in in coinciding that, right? So it doesn't really matter what's the length. They can be of the same lengths, doesn't really matter, equal to the radius of the circle. All right, so I have linear speeds. Now, if this is this little thing, this little arc, let's call its length L. Now, if it lengths L, it means that my minute hand made a full circle plus this L, while my hour hand made only the distance of this L, right? So I have the linear speed of one, I have the linear speed of another. So it means that Vh, that's the hour times unknown time t, covered L, right? Now, at the same time, my minute covered the full circle plus L, right? So Vm speed of minute, linear speed, times t is equal to 2 pi r plus L. So I can substitute this into this, and I have an equation for time t.  Vh is 2 pi over 12 L Vh, r times, one second, L is equal to Vh times t. Vh is this, which is r times omega h times t. And obviously r goes out. Now, omega m is equal to 2 pi. This is equal to 2 pi over 12, from which 2 pi also down. So we have t equals 1 plus t divided by 12, from which 12t is equal to 12 plus t, from which t is equal to 12 divided by 11. This is the time in hours, basically. Everything is in hours here. This is one hour and a little bit more. So one hour will be when the hour hand will be at one, and a little bit more, that's exactly the time needed to catch up. So that's the answer. This is the time when they will need a game. Not by the way the whole number of minutes. Okay. Now we have a river, which goes straight with width s. It has certain flow of the water, which is unknown. Now, I have a boat, which is supposed to cross. So I'm always going perpendicularly to the banks of the river. I know that my speed of the boat is twice as big as the speed of the current. So the current goes this way, my boat goes always this way. But obviously, during the time I'm reaching, my water will move me from this point somewhere here. So my real trajectory would be this, which is the combination of my movement always perpendicularly plus the water pushes me to the right in this case, and I will end up down the river, down the flow of the river. The question is, what is this distance? Well, let's just think about it. Now, what is the time I can theoretically cross the river? Well, that's the s divided by 2v. That's the time. So I'm actually covering this distance across the flow of the river in this time. Now, with this time, using the flow during this time, it is always moving me to the right with speed v. And what's the distance it will move me further? This one, which is s over 2. So if my speed is twice as big as the speed of the flow of water, then I will be pushed by the water by half of the widths of the river, right? Okay, next. I have the system of coordinates, x, y. So the whole thing happens on a plane, x, y plane. I have one car here at A0. A is this length along the x-coordinate, and 0 is because I am on the x-axis. Another car is here. It's x-coordinate is 0, but y-coordinate is b. Now these cars are moving towards each other, towards the center, towards the origin. Speed u and speed v. Uniform speed, obviously. My question is, well, obviously they are in certain distance right now. As we start moving to the origin of coordinates, obviously they are making their distance between them smaller and smaller. Now these speeds are different and distances are different, as well they don't really have to meet. They will go through the center and further down to the negative side, and this one goes through the origin of coordinates and goes down to the negative side on the y. And then the distance between them becomes greater and greater. So first the distance is diminishing, and then after a certain time where it was actually the minimum, it will start growing again. The second question is, how long will it take for them to reach the minimum distance between them given their positions and speeds? Well, all we have to do basically is to calculate as a function of time the distance between them, right? So if there is a time t, which is past since t is equal to 0, this car is here and this car is there. Now after that time, if we have time t past, we have uniform speeds, right? So my new position of the first car, let's call it A of t, that's the position, is equal to, well, obviously x coordinate is 0, but this one would be A minus u t A. And then as the t is increasing, every second I'm moving to the left by u and that's why this is a position of my first car. Y coordinate is 0. Now, position of the other car is, now it goes this way, so x coordinate is always 0. Y coordinate starts with B and then it diminishes by V every second. So that's the position. So I know positions at time t of both cars. Well, let's find out the distance between them. Now, if I know two points on the coordinate plane, on the system of coordinates, I can very easily find out the distance between them. So if you remember it's x1 minus x2 square plus y1 minus y2 square and square root of them all, right? All right, so square of the distance, let's say this way. I will minimize the square of the distance instead of the square root of that distance because it doesn't really matter since I'm minimizing. If I'm minimizing square root, I have to minimize whatever is under the square root, right? It's monotonic. So what is the distance between them? Square of the distance. It's this minus this square, which is A minus u t square minus 0, right? Plus this minus this square, which is B minus v t square. And, well, lo and behold, this is just a quadratic polynomial, right? How to minimize quadratic polynomial? Well, if you have a quadratic polynomial which looks like this and A is positive, then it has a minimum at point minus B over 2A. Well, these A and B have nothing to do with these A and B, just the coincidence. I'm talking about coefficients of the polynomial. Well, we have the polynomial, so let's just change it slightly so we will have a clear understanding of what is our coefficients. Okay, what's at t square? u square plus v square, right? Now, what's at t? Minus 2A u t, right? So plus t minus 2A u and minus 2B v. That's the t. And my free member, and nothing depends actually on this free member, would be A square plus B square, right? So this is my polynomial. Again, minus B over 2A, this is my B. So minus B would be 2 times A u plus B v. Divided by 2A, which is 2A square plus B square. So this is the time t, and obviously I can cancel this too, and I don't need these brackets. So this is my answer. This is the time it takes to reach the minimum distance between these two cars. Well, that was my last problem. I do suggest you to go through these problems again. Go to Unizor.com. That's, you have to go through physics, for teens, mechanics, kinematics, frames of reference, and then the problem number two. And just try to solve these problems again, just by yourself with a note pad and a pen and see if you get the same answers. Other than that, that's it. Thank you very much and good luck.