So, a while back, a friend of mine, Hi-Wiz, started Defcon 101. He wanted to let people know that, you know, if you haven't been here before, this is what you can expect. There was a lot of fun. Some of it was, you know, serious, but either way, ultimately what it did was it set the ground rules so that you understand what you're doing when you're at Defcon. Who here has never been to Defcon before? That's awesome. Oh, that's amazing. You guys have no idea how awesome that is. That is awesome. This is Defcon. I'm a noob. Everybody was a noob at something sometime. As they said on Adventure Time, sucking at something is the first step to being good at it. So, with that, you know, I just want everybody to know you are in a community. Everybody at some point didn't know how to do something sometime. The awesome thing about Defcon is there are a lot of volunteers here. These are people who want to help you. Now, some of them are going to want to help you get from room to room. Some of them are going to want to help you actually understand stuff. We're going to go over all kinds of cool stuff about Defcon and we're going to go over a few rules too. First, welcome to Las Vegas. Pace yourself. You've got a few days, so you don't want to end up like this guy. You know, it's actually pretty important. Stay hydrated.  Try and keep a good balance. You know, I'm not saying don't have a good time because you truly honestly want to have a good time. And having a few beers, having some drinks, that's cool.  And second of all, you certainly don't want to be hung over in the desert.  Alright, there's important things you need to know. The countdown. We're going to count down from three. Three. You're going to get three hours of sleep a night at least. Without this sleep, you are not going to be able to function. Trust me. The first year that I was here, I was on Capture the Flag. We operated 12-hour shifts. The second year that I came to Def Con, we did Capture the Flag and it was 36 hours straight. Yeah. And then I slept through the rest of Def Con. It was awesome. He's never actually recovered either. So, get at least three hours of sleep a night. You've got to be able to function. You need at least two meals a day. You definitely want to make sure that you have your energy up because there's a lot of walking. I did 20,000 steps yesterday. By 11 o'clock, I had done 10,000 of those steps. So, you know, this is one of those things. You need to keep your energy up. One, everybody needs to bathe at least once a day. Please. Brush your teeth. You know, this is something that some people sometimes forget. You're in the desert. You are going to get stinky.  So, please take that bath. Def Con Prud.  Must have got something on the airplane. Uh-uh. You got something at the conference. Fist your friends. Feel free. Fist every single one of them. It's going to be good for you. That feels so good, too. Trust me. You know, I had to pee really bad, so I'm running around trying to get here on time.  I know.  Are they on the stage? No. So, help me out here.  We're going to say this after a few of these slides.   Evil hackers are always depicted as either having hoodies or a ski mask. How I like the pipe. Or a black hat. Hey. So, we're going to hear some of the basics. Hold the door. You're not the only person in this conference. I don't know if you've noticed. There's a lot of people around. There's a lot of people in the hallway. So, hold the door.   But try and keep your head up and pay attention. And for God's sake, don't hold a family reunion in the middle of the hall. There isn't enough room for everybody to be able to do that. So, if you get an opportunity and you recognize, oh, there's more than two of us, let's step to the side.   Do not ruin everybody's time. You know, everybody is here to have a good time. We're here to learn. We're here to meet friends. We're here to keep up with friends. But the object here is to have a good time. And there are a few people, a few bad seeds that are going to try and ruin everybody's good time. Don't be one of them. Because, you know, we're okay. We're cool. This room's cool. There are people that aren't cool.  And you just don't want that karma coming around. Please do not heckle. You may be welcome to heckle me. This is an interactive talk. So, if anybody has anything that they want to say at any point, there should be two microphones. Feel free, get up. If you don't want to get to the microphone, stand up, hold your hand up, let me know, and shout it out. Can I have a hug? After the talk. After the talk. Remember, see the previous slide. All right, hugs. This is one that everybody, you know, my shirt, three hugs here, awkward hugs. Because not everybody wants you to hug them. I have, my boss is here. He probably does not want to hug from me. You know, and I just met his nephew. He probably does not want to hug from me. If I offer them a hug, they may actually take it. And then it's an awkward hug. Ask permission. Phones. Who has an Android phone? Don't hold it up. Yeah. Read the rest of the sentence. This has been a bad week for Android. Dude, my iPhone friends are trying to send me messages and I'm not downloading them. There are a lot of people here. There are a lot of phones here. There are a lot of cameras here. Expect to be in a picture. Not everybody wants to have their picture taken. We understand that. But you know, there are going to be times where you're in a crowd. You're in a public place. Somebody may take your picture. If they do, kindly go up and ask them to delete it if you don't want them to have it.  There's a lot of press here. I think there's a record number of press here this year. There are film crews and all kinds of other things. You may end up on TV. You may end up in a movie. You could end up on this guy's camera.  You know, so if you do end up on any of these and you don't want to, just, you know, let the guy know. Here's one. Not everything is free. Notice I put this one in fine print. Just because you see something laying out doesn't mean it's free. Especially, you know, you're going to go into the vendor area. You're going to go into some of the contests and villages. They've got stuff laying out. It doesn't mean that it's yours to take or touch. You know, so make sure that it's appropriate if you're doing something. Yes, stand up.  So, those of you who didn't hear it over the laughter, he said if you find a USB stick on the ground, please, by all means, pick it up and then put it in your personal computer to read and see what it is. Yes, if you have a work computer and you do, you know, government work on it, by all means. Because my social security number and information isn't out there enough. There are five billion Chinese people and I think most of them have it now. So, have a plan. There's a lot of stuff going on here.  And you'll notice this room filled up.  But, you know, it's, so try and have a plan. Make sure that you know what you're going to do. Feel free. Don't be afraid to camp out. If you see a talk and it's not necessarily, you know, a talk that, it's okay. It may or may not be a good talk and we're going to get to that in a second. But, you know, say it's a talk that you don't want to attend but the one afterwards you do and you know that there's going to be a line around the corner, consider camping out. You can't let me smile as you know that. What's that? You're screwing with my system. Now, the talks. There is no such thing as a bad talk. I can tell you from the call for papers review board, there is such a thing as a bad talk. But the approved talks, there is no such thing as a bad talk. Just because you don't like it doesn't mean it's bad. Just because you think you know doesn't mean that everybody knows. In fact, that is probably the two most common things that I hear in the hallways.  It's not the case. Not everybody knows it and not everybody is thinking that this is going to suck. So, you know, if you don't like it, that's awesome. You're entitled to that privilege and opinion. But don't try and, you know, mess it up for anybody else. See the assets line. There are a lot of villages this year. Villages are awesome because villages are where you can go and get hands on. Notice the villages come after the talks. A lot of the talks are going to play into the villages. You're going to see a lot of different things, whether there's a biohacking talk or a car hacking talk or let's go down. Internet of Things talk. There's all kinds of IOT talks. And now you can go to these villages. You can hear additional talks at those villages and you can get some hands-on experience too. Especially hardware hacking village, crypto privacy village, lockpick village, social engineering village. If you haven't stopped there, you have to stop there at least once. Leave your wallet in your pocket. Just so you know, the SE village actually does have stuff going on today. So you can go over to Ballet and get in there. They do have activities and talks and that kind of stuff happening today. Thank you, sir. And of course the wireless village. The wireless capture the flag. Please, sir, you just came in. Come up front. He looks lost. Don't pass that, Mike. Lost isn't that tall. Is that the monopoly man? All right. Now, contest and events. There are way too many contest and events to list. I'd like to hear some highlights. Here's the highlight. Lost challenge. Lost challenge is one of the hardest challenges there is. It will take all of your time. Anything that you have access to at DEF CON probably contributes to lost challenge. Anything that somebody else has probably contributes. I've got a goon badge. This helps. Makes noise too. I've got a vendor badge. Vendor badge helps. I've got a speaker badge. It all contributes.  Ask them. If you're going to participate in this, I highly encourage you to try and meet somebody. What did you guys drop? Oh, what? What? Dude, you didn't even tell a joke. You can't drop the mic. Swag inventors. Swag is open today. Vendors opens tomorrow. This is awesome. DEF CON is unique. Obviously, we've got DEF CON branded stuff. But, you know, for a conference, a computer security conference, hacker conference, we have a vendor area. And it's actual vendors. This isn't, you know, like DEF CON. It's not RSA. It's not any place like that. When you go in, you can buy stuff.  You may never even use. You've got guys that, everybody in there, contribute something to the community. And so, you know, it opens tomorrow. And I think that you guys will like it. Prepare to separate yourself from your money. Demolabs and workshops are new to DEF CON this year. Demolabs, they're a brief introduction into, you know, different tools and projects. And workshops are training opportunities. The workshops are actual hands-on, 48 hours of training opportunities that you just can't get. If you were at Black Hat, and any of you that were at Black Hat, you know, $4,000 for a class, it might not be $50. It could be free for the workshops. So if you didn't sign up, consider signing up. They're full now. They're full now. If you didn't sign up, consider signing up next year. Yeah, or camp out. That's what I heard was good, too. Just camp out. Talks, talks. Nikita. Alright. So, I have a group of people that are sitting up here. And the reason that I asked them to come up is because as much as I love to hear myself talk, I want you guys to get some more feeling of an understanding of, you know, what's involved with being at DEF CON, how do you get involved, how do you participate, what can you do to participate. So these guys are going to give you some experience. Some of them are going to be experiences. Some of them are going to be, this is what I do in my department. Some of them are going to be, you know, I have one, this is brand new on the panel. We actually have an attendee, one of you guys that we asked to be participating. Yeah, down at the end. And he's going to give you a story about, you know, how he got into DEF CON, and it's actually a pretty inspirational story. So we're going to start it off, not in this order. I'm going to start with Russ, because he's sitting right next to me. And Russ is going to give you whatever he wants to give you. Oh, yeah. Oh, yeah. Yeah, who wants a fist? Yeah, there you go. That's not where I want it. Yeah. Why'd you say that? My name's Russ. I am the Chief of Operations for the conference. I've scared Nikita off. I have been here. This is my 17th DEF CON in a row. I'm not a noob anymore. Basically, it excites me to see all the new attendees come every year, because I think it adds a lot intellectually, creativity, your experiences, your inputs, your insight, your research. I'm going to tell you the same thing everybody up here is going to tell you. And you're going to get tired of hearing it and talk is over. And you will get out of DEF CON when you put into it. And I helped over the years get a lot of these activities, the villages, contests, started. And the people that have the best fun, the people that are out there really writing cool blogs or doing cool research, or people that actually got involved, met people, made new friends and did cool stuff.  So I want you to go out, do a lot of things, learn a lot of things. I brought my kids for the first time this year. After 17 years, that should tell you something. I haven't been really comfortable with it in the past. You know, DEF CON of old was different.  You know, I started at DEF CON 6. It was at the Plaza. I think we had about 300 or 400 people there. And if you think about it, that's about the population of this room, maybe. And that was the entirety of DEF CON 6. And everybody sat around and we did a lot of hacking and we learned a lot of things. I mean, there were people sitting down showing other folks how to make a network cable. Because at the time, that was still a fairly new thing unless you were in the field. There was, you know, switching and routing and all this interesting stuff. And they were still writing windows exploits that you could do across the Internet and break boxes. And people sat around and had conversations. So if you want to have the most fun you can possibly have here, aside from the fisting thing. Seriously, get involved. Do stuff. In the red shirts, if you have a question, ask them. You know, I've directed more people this morning to where things are, to answer questions. I love doing it. Because if you'll get involved and you'll go do things, that's why I do this. Thank you, Russell. So, you know, Russ is right. Ask. Meet people. I just got a business card today. It's actually kind of fun. For an international DEF CON meetup. One of the cool things is that DEF CON is international. There are a lot of people here. But you may not recognize that there's somebody that's here that speaks your language. And we all have something in common and that's the technology. But there's also the fact that we can find other people that speak the same language so that they're more comfortable. So, feel free. Ask around. Nikita is awesome. She's not going to tell you that she's awesome, but she is. She's amazing. Nikita runs the back of the house. And, you know, she has a crew of people.  Nikita. It's so... So, we will be... With the spelling. Oh, yeah, that's awesome. Nikita. Nikita. It's N-I-K-I-T-A. No, it's not. That's not on spelling. That's exactly what I have in my phone. Yeah, that is now perfect. Slash Nick. Okay, so... Backdoor crew member. Give us a little idea of... I love you, big sis.  I'm just going to take that with Grace and Ruan. What did you ask me? Give me... You know, yesterday, we were talking a little bit about the things that you do, the things that people don't recognize, that don't understand what it takes to make this happen. Just do a list. Yeah, you can do a list of things. In binary. It takes patience and... a love for all of you fuckers. Because if I didn't have that feeling of belonging, I would not work, you know, 16, 20 hour days sometimes or, you know, answer guys at major browsers at three in the morning to register them for a workshop on a Sunday. Because I'm doing it manually by email. I do the CFP review board. I manage... When you submit a talk to speak here, I am the one who gets it and then passes it to the board and, you know, handles all your questions for speaker liaising. I help plan pretty much every aspect. Scheduling floor plans. Scheduling floor plan. Workshops. I've started numerous contests and events, but here's the thing that I do. I don't have time to do them. I just want to give you a really good idea and you will run it. I'm relatively good at that. I don't know.  Stuff and things. She does stuff and things. Nikita sells herself short. You know, call for review, call for papers is ridiculous because the number of people that submit talks is enormous and the fact that she has to wrangle every bit of that. You know, we talk... I just said we start planning in September and the reality is we do. Actually Nikita has already started planning for next year. So these are things that I just wanted you to get it. You guys, to understand that, yeah, DEF CON is what it is. You guys pay $230 and you get into it what you put into it, like Russ said, but there are a lot of people that put a lot of stuff into it. There's a lot that goes into it. There are volunteers that, for some people, it's a part-time job. I can tell you, doing the vendor, it's a part-time job. Just trying to wrangle that and that starts in September as well. So, Ali John actually talked last year for a panel and he gave a little bit of an experience and Ali John is a good example of what happens when you meet people. You know, through common experiences, but really what we tried to do was bring Ali John into the fold, out of his shell. So, I've been attending DEF CON for six years now. The first three, I was doing Lost's Mystery Challenge and that was one of the best things ever. You have to interact with so many different people at so many different skill levels, crypto, different languages, Korean, Chinese, lock picking, everything under the sun. So, having that connection with a whole bunch of people, amazing. I still stay in touch with all of them. They're in different companies across the country, across different industries. So, if you need something a few years down the road, you can call them up and be like, hey, how's it going? I need X. But, um... Oh, no, no, no, no, no, no, no. Not what I meant. Oh, okay. Cool. Thank you, IO Active. Cool. But the only other thing I have to say is I would not be where I am today if it wasn't for everybody in this room.  So, thank you guys. No, nothing. But I still love you. You know, I'm going to take a second. You see this shirt. It says, hi, I'm new. I actually have a whole bunch of these shirts. And I want to hand a few out before we get down to some of these other guys. Jeremy, can you help me? Of course. Okay, awesome. I will show you where to throw them. Okay. No point. Okay. Well, first of all, I want to say these two guys right here up front. Pick me. Which one? First group of anyone. I didn't know. You the first year? The second year. They tried to s-e the information. They were like, oh, yeah, we're going to help line up. Can I get a goon badge? I was like, wow, really? Wow. They're starting them that young now? That's awesome. So yeah. There you go. And then other than that, toss that way. That way, huh? Woo! Try not to s-e. Perfect. All right, I'm going to have a few more of these too because we're going to play. Jay's got really big arms. He can throw far. Yeah. Pro gets stuff. It's your birthday. It's my birthday. Okay, let me see your ID. Let me see your ID. Make sure it's somewhere else. Yeah, yeah. Thank you. Thank you. Lesson number one. Opsic. All right. So, you know, Jeremy, I've said his name out loud a couple of times. Jeremy and I are friends. Been friends for a while. Who's Jeremy? Who's Jeremy? Yes.   Don't, yeah.  Jeremy has just always been involved but not in an official capacity until recently. We really can't get rid of him. I mean, we've been trying every year. Yeah, so now Jeremy's actually involved and I want him to give you guys an understanding of, you know, from his standpoint, he just involved himself. Big time.  I'm a good fister. Ding. I feel a little over-involved. Please take as long as you'd like to speak. Oh, Lord. You don't want to tell me that. Yeah. You got another hour.  That's what I was up to. Ding. My name is Jeremy, Krypt. Most people will know me as Krypt here. Krypt here. No, not Kryptier. I'm just Krypt. I don't even, I don't count number of times I've come. Definitely not as much as these guys, but, uh, wow, that was crazy. No one got me on praise? Crazy. Wow. I will say that my experience at Defcon has been all about people. I've wanted to do the contests. I've wanted to do everything. I get to hang out with Ryan a lot. I get lost. And he always starts off talking about the contest and then I'm like, now I can't do it. So it's all about the people around me, the people I've met. There's a lot of people, I mean, like these two, I'll probably see them throughout the entire con. I met some people in registration. In the registration line, talked for about 20 minutes. I think Jay and I did. Just sat. I'm Jay. I will say from my experience, and for yours, it's been said a lot, but it cannot be said enough, is talk to the people around you and find things to do. I've seen people sit down in the hallways, especially back when it was at Rio when you had the pass. They would just sit right in the middle of the floor because they had the stickers on the ground and just sit and talk. And I'd just walk right up to them and sit down and start talking. And it's one of the only places I've ever been where that's okay. And it's actually kind of cool. I don't have any friends outside of con, basically. And so I come here to meet people. Yeah, I don't have any friends. Yeah, so I came a couple of years ago, I think at DEFCON 20 is the first time I was working to help one of the artists here, Eddie Meis, who is an amazing artist. He's set up in the vendor right now, right? Yeah, so he'll be set up in the vendor. I had worked with him. We made the drive from Colorado to Vegas. And I just got to meet a lot of people as they came and bought the art. Yes, yes, he's awesome. And so with that, I then started just meeting more and more people. I mean, I'd worked with Russ as well. And then I think the next year, what, 21 is actually when my grandmother died. Yeah, that's a sad story. I'm sorry, I just remembered as I'm going through. And then 22. Moving on past that. No, I guess the big part is we all here want to, apparently we can't hug anymore. How's the hugging? We're allowing that to go. It just says ask first. Okay, asking for hugs. Sorry, I just remembered my grandmother. I'm sorry guys. Let's see, hugs. Appreciate that. Alright, so I'm going to say you move on. Thank you, yeah. Jeremy actually is a really good example because he's like about half the guy. He's the opposite of me. My first two years at DEF CON, I went in, I did CTF, I went back to my room, that was it. I interacted with the people on my team and that was it. I'm scared to death to meet people. This is something that most people don't know about me but it is true. I really have a hard time. And it's awesome to be in an area of community where even if I don't know you, that's fine, you can come up and chat with me and we'll talk. But I didn't used to be like that. Jeremy is the opposite of that. Jeremy is the kind of guy who will go up and talk to you. Alley John, he do the same thing. So, you know, it's a good example of being able to be involved. There's a common theme here, involvement. Now, Jay, actually. I'm Jay. Hi Jay. Also much like Jeremy but without the sad story. I'm sorry. I'll get in trouble for that later. You know, he's the same way. Jay is awesome.  So, you know, I'd actually like Jay to talk to you and actually tell you about himself because you will feel like you've known him forever. Can he have a mic? Blue or red? This is my second one. Hi, so I'm Jay. Nice to meet you, everybody. If we can go around the room and introduce ourselves. Okay, all right. So, this is actually my second Defcon. My first one was last year. And I came with this guy here, Jeremy. He told me that, or Crypt, I apologize, Cryptier. He told me that it's Cryptier. It's not Cryptier anymore?  So he told me to come out to Defcon.  So he told me kind of what was involved and how exciting it was. Is it say Cryptier? Yes. Nice. That's legit. So, came out here and I got to meet a whole bunch of new people and to be honest, kind of the hacker industry. Legislate. You know who gets to fix those typos later? Ikea. You do? And Leo. Oh, do you? I edit those, yes. I don't know what that even means. We'll see what comes up. This is fun. This is fun. We do this all the time. I love you, transcriber. Man. All right. So anyway, so again, the whole computer crypto world is really new to me. This is amazing. I can't believe it takes what I'm saying and puts it up there. But so I'm more of a talker. You know, I enjoy speaking to people and getting out there and meeting people. And I'm very, very social and very easily to, very easy to approach, I guess would be best. Approachable, yes. Approachable. There's a word for that. There we go. I'm very approachable. Easy going. You know, if you ask me a question, I'll give you an answer. But I promise whatever you ask me, whatever information I give you, I'll get twice as much information from you. So please, please be ready and be aware of that. So I did meet one of the guys here last night. He's actually sitting over there. Sid, right? I believe. All right. I'm pretty good with names. Billy. And we do, all right. Anyway, so I was talking with Sid. He was just asking me a few questions. I'd given him some pointers and kind of letting him know, as everybody else here said, just get involved and go meet people and talk to people. And one of the things he came up with, I thought it was pretty cool, was be curious. Curiosity is a good thing. So go ask people what's going on. Say, hey, where is this? How can I do that? How does this happen? And how does this work? And be humble. Don't be the guy who says, as Mike said, I know that already. It's no big deal. So kind of be humble and say, hey, that's cool. I'm glad you're teaching me something new. And then so it's curiosity, humility, and respect. So be respectful to people. So that's the thing that I've learned here. If you have those three things, I think you'll get pretty far here. That's my little credo. And welcome to SIT. Thanks. Come on, SIT. Stand up. Take credit. Take credit. There he is. So like I said, whatever I learned from you is going to be twofold of what you learned from me. So please come around, run up to me, and ask me what's going on. And we'll figure it out. If you want to know more about me later, I'll be up here all day. Awesome.  Carlos is one of you. And I asked Carlos to do this. I met him last year after the panel talk. And he told me his story. And his story actually is inspirational to me, maybe not to you guys. But I also will get on my soapbox and talk about how awesome DEF CON is. And I will talk about how awesome this talk is to those people that are leaving. But I want Carlos to kind of tell you a little bit about himself. Tell you a little bit about his story. And then, you know, how he came to be involved also. So, thanks. Hi everyone. I'm Vlad. My name is Carlos actually. I've been coming to DEF CON for a lot of years. Unlike the panel here, I really never, never could be that involved. I came to the States when I was 16. And in order to learn English, I figured out that I could buy some magazines. And somehow I found a 2600 magazine that led me to the 2600 meetings in LA. Now, some of the goons here probably, you know, more likely know that a lot of the goons and people that are in LA have been working at DEF CON for a long time. So I was privileged enough to meet some of them. Unfortunately, my English was pretty limited at the time. Or keto English. So it was tough, you know, to be there. I didn't, my legal status was null, so I was a legal precedent. And it was tough. But, you know, I scored reviews and I really liked them. And so somehow I figured out that there was this conference at DEF CON and what I did is I took a boss and I ended up here. My first DEF CON was pretty short. Like, maybe three hours short. I walked into DEF CON and I was so happy at the time I think they had this paper thing. And so what I did is I walked around and I probably looked like a cleaning crew at the lessons bar. So I was with these guys. It was kind of cool. And so while traveling I just heard people. And the first thing that I heard was that there was going to be some cult. And I didn't know what the cult was. And it was the cult of the dead cow. But for me it was something different. I didn't know, for me cult was, this is evil. And I kind of got a little fence in there. But then I heard other people talking about facts. And so apparently there were going to be facts on the CON. Some of them from the FBI, some of them from the CIA. And so I put the two together and I realized well if the feds are here and we got the FBI, the CIA, well immigration is here. So I bounced. You've got to survive. So that's what I did. It was pretty short and so I ended up going back to the meetings for a short time. I didn't have a car so I had to take the bus and make it to the meetings. But then I stopped. I really got afraid. I thought maybe the feds were there and I could reach everything. Eventually I managed to meet some people in there and they led me to school and they inspired me to pursue computers and so I did. I got involved into college somehow. That's another story because finding people like them they helped me to figure out ways to legally do a lot of stuff. I managed to get my license and a lot of stuff. I tried not to cheat the system because I know I could do it any other way and I tried to do it that way. So I really owe a lot of the 2600 people the inspiration to try to do it the right way and it helped a lot. Anyways, so my second time I was here now legally so I managed to get my papers and I was now a legal resident and so I came back. It was probably 2003 when I did my second run to the Afghan. On the way here I was driving with someone. He's a really cool hacker. His handle is a strong car son and we were driving in the car and somehow he was speeding up. We got pulled over by the police as he was getting a ticket, I panicked and I was sweating. I really thought that something was going to happen to me. The idea that you are automatically legal and resident is not difficult to digest and so for me it was a little tense really.  For the first time I was able to digest a lot of stuff. I was still pretty shy but I kind of bought and I continued to do it for some time. Then I stopped. Just like Jeremy...  Crypt deer. Crypt deer. Things happened to your life. I had my sister pass too. He's not a sad story but it really happened. What are you doing? I'm crypt deer. Anyways I came back and the third time I came I was a resident. I was a citizen. So I experienced Defconn as I transitioned to my legal status but I made a mistake. I was fortunate enough to meet a lot of cool people. I know some of these people by face but I'm never engaged and I know many people that are not here and I know some of them by faces from many years that I came in. I was hiding. I was really shy and afraid and I didn't want to speak up because I was afraid of my inhalation and when it came to technical stuff it was difficult to engage. But at some point I realized that that was not really helping and so what I decided to do is you know, come out of the closet if you want to call that and then really start talking to people and meet people and engage with people and just say, hey, I'm plugin. What are you into? And that really has changed a lot. If you look around you're surrounded by a lot of people that share your passion. This is about security, technology. You're not going to find that anywhere else. This is your opportunity to meet people that share the same things that you like. You might meet some of the brightest people in here and if you don't think about this that you're really losing out. And that's one of the things that I learned I really lose out on some of the things that I could have done better. Now, some of the people here are helping my career. I got into security because of them. Anyways, I don't want to really bore you about it. You know, the point is that I understand what it's like to be here for the first time. I got some of these fortunes and I found a way to overcome them and I met interesting people like Mike and now I'm meeting more of them and so it's fun to actually do that to get to meet people and to have fun if you go out there and meet people at the bar and drink and whatnot. So, you know, have fun engage with people go to places if you don't want to do something try to find something to do. I'll be at the Crypto Village volunteering this year if you want to come by and say hi, please do. I don't know if I'm taking too long or if we're doing good. So I'm going to tell you I don't want to, you know, throw out the mic but I'm going to tell you a story because this is this is how I got my handle and I think that handles are something that kind of got lost along the way when I did the first test someone asked me for you and I came up with something I couldn't even pronounce it to be honest so I started working and I had to spell it and it just did sound like the way I did it so anyways, at the 2600 meeting there was another lost it's the lost from like nothing to do with the one here he was a Mexican-American I believe and he's the one that kind of schooled me on what the handle was about because when I introduced him I said hey, it's Carlos and he was like dude do that here he said handle so I came up with again something else and it was really good so it just kind of went like that but there was some other guy he's handled a get G-H-E-N-2 probably some of the goons here coming he passed away too he was a really awesome person and the way that I got my handle is one day he just said hey, hi, I'm again I didn't know what to say so I looked down and there were a bunch of power cables and the first thing that came to my mind is hey, I'm vlog it was the easiest thing for me to say so I didn't like that and then it stopped and so I wanted to tell you that story because nicknames or handles are important when I came here it was difficult just to present myself but handle is one thing that goes with you is your alter ego and in my case as an immigrant that was perfect and I want to quote a fight to some other day in all the years that I've come here to that con I've never, never, ever encountered someone asking me where I'm from no, really, done this is one of the best days like no one comes to say hey, are you from this place or that place people are like Microsoft or Rocket 7 well, maybe they do want to know where you're from but if you're here at the con it doesn't matter you're here as you're here you're a geek, techie or a sec whatever you want to call yourself we're here because we love security or something we're going to go ahead and go into the handles alright, so we're going to go into the handles I think I spoke too much but hey, like you I understand and so please do engage you know, talk to these people and before I leave the mic I really want to say thank you very much because these people spend a lot of time putting together this for you guys so I think we should give my round of applause what do you think? so Plug actually did bring up a pretty important point I have been calling everybody by their name except for Kryptier Kryptier what? and so you know your handle is kind of you know, this is a story about you this is your badge of honor some people try to make up their own handle and that rarely works you know, if you say I am as an example Death Lord Slasher Man Death Lord Slasher Man Morpheus it doesn't work how many Morpheuses are out there right now? I was one did I say one? or Neo or anything else you know, you want to be something unique Russ's handle is Vertigo it's a fun story he'll tell you if he wants to it's great fun it's a good time as Plug, my handle is Wiseacre and it actually came from when I used to work at SCIC and they were trying to get into computer security and they put out a brochure that said Blackacre where security lives and it was ridiculous it was absolutely the worst thing that I had ever seen so I put together one that said Wiseacre where the smart ass lives and published it and eventually that became my handle Ali John though Ali John tried really hard to be revolved but he can't be revolved because when we met him he was hanging out over at Blackhat the first time that I met him and he was wearing a lab coat and he looked like a miniature version of Joe Grant, Kingpin so we tried to figure out how do we get Ali John and Nick that reflects a miniature Kingpin we tried Babypin diaper pin your Nick needs to be fast you need to be able to say it fast Pushpin Ali John is now Pushpin so what we're going to do is I'm going to take 10 volunteers from the audience before you volunteer sir understand that there's a good possibility that we're going to pick on you because what you're going to do is you're going to go up to the mic and you're going to tell everybody in this room 5 things about you that people may or may not know and I don't want to know what languages you program in I don't want to know how awesome you are at Destiny what I want to know is some things about you as a person Jeremy might want to know about Destiny that way you guys can play each other so Jeremy's going to help me out and I would like to get 5 volunteers that can tell a story and I'm going to give an example 10 5 things here's one thing about me I am a cancer survivor anybody here that has ever heard the phrase cancer brain it is true, it is a real thing you can feel free to laugh this is one of those things where this is not as sad as you ever I knew it I love you clutch don't be an ass hat they're also trying to follow the rules you're not helping I also had a heart attack a few years ago and as a result people have been these are funny things nobody else has participated I had my heart attack in doctor's office which was actually kind of fun I was in the line of the pharmacy to pick up some drugs and I had a heart attack and actually on the way to the hospital my phone goes off it buzzes and I actually check it because it was a 30 minute ride to the hospital they had me on life support testing me because I had not picked the name of my deadpool team he went ahead and named it code blue so when I come out of surgery because they put a stent in I come out of surgery and my wife says do you want to let people know that you're doing okay, here's your phone first person I called was Jeff she says are you sure you don't want to call your family I was like no this is too good so you already know that I am scared to death but you've heard I have a lemon for a body my friends often tell me that it's rule number two for me it's going to take a double tap to kill me anybody who want to venture what a good nickname would be for me besides Weizel what third time's a charm I didn't have to come up to get your shirt seriously one of the things you want to do with a handle you need to be able to right off the tongue third time's a charm might be a little too long when you call me on the phone there you go everybody understands how this game is played so we're going to go ahead and take our ten volunteers each of the volunteers is going to say five things about themselves and then we're going to the panel is going to bestow a nickname we are happy to take volunteers from the audience also bestow nicknames please do not just simply say something and then put kitty at the end you want to volunteer alright can you guys help wrangle the volunteers please Jeremy jay alright so raise your hands let's see you and the strikes because we want to have a little university very nice are they going to choose? I like the guy back here with the beer so do we all get to just go pick someone we all just get to go pick someone what about that guy that guy you I pick him that's going to be fun we got ten alright let's go ahead and start please introduce yourself I'm from the pacific northwest I've been to Antarctica I'm an autodidact I've been playing with computers longer than I can count but I know squat dittle it she said she plays with computers yeah diddly parenthetical squat thank you actually if you could come up I would like to give you a shirt because you are fucking diddly everybody give me a please available after the show you can talk you can tell her how to use computers next okay I'm from New York I'm going to run the New York City marathon for the first time this year I have four kids I would never usually be up here but since you all said to participate I'm participating so it's completely out of character completely completely and I have a twin sister that would be up here if she was completely outgoing so I have a twin sister that's interesting that's interesting can we use a little bit more information sure we started off kind of packing when I was a kid and then got married, had kids and just got back to it within like a year or so ago I was doing like math teaching college math chaser, who's like chaser I like that chaser that sounds good hold up I got a shirt for you too thank you very much let's see I just moved to the Seattle area from Baltimore, Maryland I was an army brat growing up so I got to live all over the world a new development in my life so when I was younger I was actually studying classical music and I dropped out to take care of my mother who was also a cancer survivor moved back to the farm to care of her for a while moved to Baltimore got back to school and I just finished a master's degree in computer forensics and it's the first master's degree in my family, it's kind of a big deal that's kind of awesome what do you do for fun? I like hiking I like yoga and my mentor actually calls me Padawan, but it's hilarious to me because I'm a total truckie best nerd ever B&E there you go that's an awesome story best nerd ever and you are B&E for fun welcome to the community so I came to shirt to a friend and he looked at it and he's like are these in European sizes? apparently I didn't size him properly either alright let's step up sir first security conference for me sorry I'm kind of nervous I'm allergic to a lot of things I'm the reason you guys can't eat peanuts on the airplane I'm allergic to lettuce which is strange and people usually don't believe me but I was really thankful when my parents made me eat my veggies as a kid until we figured out what was going on there I really like snowboarding and I used to in college race boats I'm allergic to epi epi here epi just don't no peanuts are you allergic to cotton? there you go again thank you epi I'm sure that you've got a good story for us sir I got involved in hacking because my things were always breaking and that just wasn't okay I like to people watch I'm curiosity driven I'm in front of a mic wow this is interesting okay tell us what do you do for fun? computers primarily sometimes I watch TV that means you at least get out a little bit what else do you do for fun? Friday Night Magic one track one track I'm liking this one we're gonna for a second tell us a little bit more about yourself who are you here with? I actually managed to sell my employer that this was a good professional development you're here by yourself? no I actually got one of my coworkers here with me it's not his first time though okay well fantastic I actually do like one track because it does kind of focus to sir I think that's gonna be good sound good? thank you for audience participation and welcome to our track anytime now there's a lot of space between you and that mic sir yeah you made me jump up thank you closer closer open your mouth closer alright so I'm relatively new to the security field I just started this past year it was my junior year in college I got involved in UW Tacoma security group and then got involved up at UW Seattle and I'm actually coming from UW Seattle with a bunch of UW guys I'm majoring in computer science shout out to the guy before me I am very into Magic the Gathering I play a lot of commander so uh we need to come up with a couple questions yeah go ahead let's see um magic mic done magic mic magic mic welcome oh yeah actually who is your favorite planeswalker alright I guess and you have your cards I do not have my cards but the one commander deck that I play is based off of Kara Metro the white creatures deck what's the complicated name you gave your deck um Kara Metro's creature crew like it C-Cube C-Cube I'm assuming they're all C's if not they are so you're no longer magic mic apparently C-Cube welcome C-Cube to the community yeah that's actually great Russ if he gets angry he's now C-3PO if he's angry if he's angry he's C-3PO this may be so awesome alright you sir have to have a good story hopefully I do this is my first time at the conference I'm originally from Jamaica I love motorcycles actually have four I actually funny you know if I got into security kind of by accident when I got my first computer to learn hacking because I didn't want to go to jail coincidentally you know I started learning it at a federal agency so now I do it for a living fun stuff like I said I love my motorcycle riding I love sports I play soccer always get asked why don't I play basketball I don't really like basketball but that's the bulk of it what position do you play I play soccer but I can switch role okay okay so this one is going to be a little special to us it is and I'll explain here in a second it's going to be epitome and it's because we have a lot of people that we love in this con one of the artists especially is her husband all the artwork for this and you look like the epitome of what they draw when they draw a hacker I appreciate it and you didn't get a good story so good luck copying that thank you hello everyone from Miami I guess it goes without saying that I was a little nervous walking up here until I heard that a lot of you guys are into fisting so kids cover your eyes I guess a few things I like hats I definitely like dancing so I might be that guy that you see in the hallways and I'm not twitching or anything like that just like let's see something let's see something I don't do it for free pretty good beatboxing what? no? no? no I saw where you went with that good catch that is the kind of nickname that you can wear with pride are you good with that one? personally I would own the crap out of that wiggles nice we're fisting I forgot that Mr. Wiggles I love it god damn I'm short brethren my memory is so bad I wrote down 5 things about myself at least I forgot them by the time I got up here but I'm not nervous because public speaking doesn't bother me I've seen 106 metallic shows in 13 countries I've had long hair longer than I've had short hair I didn't meet my brothers until I was 8 I nearly went into singing instead of computers I think that was 5 oh and I write a Harley back we're good pushpin and I said it the exact same time OP overprepared ah is that the right size? I just got to have more alright start the next person alright hi this is my first def con I don't actually work in computers I write for video games that's pretty great I first learned about def con you said are you telling us that it's pretty great? I am telling you it's really great I accept excellent transaction complete I learned about def con when I was reading an ok sci-fi book I think in 1999 it was called Worm by Mark Fabi I don't know if anybody ever read that you got really mumbly at the end I learned about def con a sci-fi book that first came out in 1999 2000 it was called Worm by Mark Fabi one more time Worm W-Y-R-M from the beginning stop it now it doesn't matter it's ok Simon says oh he's holding the mic look he took it right now yeah look he's owning it I used to be a high school English teacher and decided I would much rather make video games one of my favorite people is a high school English teacher more power to him I couldn't do it should we just call him Melanie that'd be so confusing I need Melanie what about only dude only dude our dads are you good with that no never mind we're doing it go ok anyway we're doing something like 2300 miles to make games instead of teach kids and when I got to California I had to buy a car I'm sorry nothing and instead of buying a car I decided I was going to buy bright green suit of armor instead and I've been very happy with that an actual physical suit of armor so you quit teaching you start video games and you bought a suit of armor that is exactly what happened I'm so perplexed by you there you go I want to hang out with him I know do you have a picture of you in the suit of armor I will show you later, yes it's my dating profile picture please tell me there's plenty of fish match I have to find this I will find I will find you I'm not going to kill you though I'm touched match I still don't like it I almost want to say perplex there's so much flow that's what I'm saying it's got to be something like this what was that convoluted too long too long green suit I don't know what that means there's a light green green what what greaves greaves g-r-e-a-v-s-s-e-r-n-t-n-i armor greaves armor greaves that was just such a small part of his story it was like the suit there it is whoever dates him I'm going to do it because of that I hope so it's got to be dating I'm perplexed I know your crypt oh thank you oh now he gets it right right I'm out of this one I'm washing my hands I want to see that picture but I'm washing my hands of this one bring the picture up bring it picture up bring it picture up I actually like it oh we got a picture I got to like it alright everybody oh green knight the picture didn't happen I was going to say alright he's going to take a minute and he's going to bring up his profile picture so can we get that picture on the projector I want it on the projector I don't think I have a thumb drive give us a thumb drive who's got a thumb drive we'll figure out a way to get that up there this is amazing guys this is awesome it says hell yes it says hell yes this is amazing you're an English teacher right describe this to us describe this it looks like he's wearing like yellow knee pads and spiky shoulders not on your life sir thank you it's pretty great it's great it's so legit right I can't believe that so um we hear you green knight green knight amazing that's so cool I double dog there everybody totally double dog there everybody here reach out find somebody with something in common that you don't already know make a friend do something get yourself involved because that's what makes this conference fun please whoever if you participated today thank you it's absolutely awesome because it's not the kind of thing that most people do and to be able to get up tell the story and have us address you and give you your nickname please wear it with pride can I say something real quick? a lot of people ask how can I get involved how can I be a goon and the answer is you know officially well we like to promote people so the only way to gain that trust is experience if you want to help if you want to be involved in something you have to take the leap and interact with other people especially those in charge and say what do you need and not always I know a lot of people would be like what the fuck why is she saying this don't wait to be told what to do the best way to help is to step in and say I can help you with that for you and once you do that you help somebody else you break the ice you make friends I can't tell you how many noobs I've met and my husband has met and my friends have met that are now gooning they showed up they got involved they interacted they're gooning here's one right here behind you it's his second year number two he's a goon that's his handle if you have the motivation and the drive and the spirit to make this con what you want it to be because it's what you make it if you don't like something do something about it don't just complain do something about it join say hey have you ever thought of doing it this way or have you ever thought about having a village for this or a contest for this or an event for that just step up and if you're you know a cool person then you end up like this asshole behind me hey I'm sorry I'm not supposed to be cursing all right we're going to go ahead and we've got a few minutes briefly for questions stand up please say is this, is there phrase it's frame it in the form of a question please yes I will talk about that hey if you have a question meet up tomorrow 6pm in the chill out space it says on the back of the card it's dangerous to go alone meet up hey if you have a question use the mic so everyone can hear you I don't mind repeating that's why we put them here and they're all over the con now you now have a voice too all right any other questions what's that thank you okay you go yeah if you got given a handle please come see me before you leave did everybody get that if you got given a handle please see me before you leave any other questions expectually GK you sir stand up it's canceled tomorrow every year that happens and this year they actually put a lot of effort into it I like the whole web page with the facts that actually was kind of fun but no deaf con is not canceled you sir yeah get there early that's really the only advice that we can give you if you see that something's good try to get there early attend the previous talk attend that talk and see what it's like you know you might find the talk in advance is something interesting so I'm going to jump in here for a second because well that's decent advice as an operations guy I will tell you last year we had 165,000 square feet we have 320,000 square feet this year we also have a crap ton of reg grannies a lot more desks everything's pre-bag thanks to Jay and Cryptier I'm never letting that go so those lines that you're having issues with are going to go very very quickly if you guys fill those rooms I will be shocked incredibly shocked heard about just get out and and take our apologies because we know it's us but sometimes we might have to clear the room because on top of all if you have any modifications to the room what they're all saying if you're a baby you can tell them we had him one more question Russ yeah honestly you know one time the village is open tomorrow thank you Jay I didn't even see your lips move oh my goodness the answer is 10 thanks guys I appreciate it everybody if you have additional I'll see you all at opening ceremonies tomorrow


This study compared the effectiveness of 3% sodium chloride versus 0.9% sodium chloride as a nebulizer solution in treating bronchiolitis in children. The results showed that 3% sodium chloride was more effective than 0.9% sodium chloride in reducing cough, wheezing, crackles and length of hospital stay. This article was authored by Shobha Subkota, Amra Kalim, Safira Huma, and others.


Hi, I'm Zor. Welcome to a new Zor education. I'd like to solve a couple of problems for certain topics which we were studying before electrostatics. Now the previous lecture was about the Coulomb's law which is the most important law in electrostatics. So these problems are basically related to to this Coulomb's law and just to complicate the issue they are related to some other topics which we have learned before. I just combined them in the problems which are related to Coulomb's law. Now this lecture is part of the course Physics for Teens presented on Unisor.com This is a free website dedicated to advanced topics of mathematics and physics. There is a course Maths for Teens which is kind of prerequisite to this Physics for Teens course. I do suggest you to watch this lecture as part of the whole course which can be taken on Unisor.com because the course includes not only the lectures presented in certain logical order, but also detailed notes for all the lectures and there are problems like the one which we are talking today about and exams and again the site is completely free and there are no ads so do it as well. Anyway, so let's just solve these. I have four problems related to electrostatics. Now my first problem is you have an equilateral triangle and at each vertex there is a charge, a point object charged with one is positive and now there is the same and the third one is negative of the same magnitude. So this is point P, Q and R. Now this is equilateral triangle and the side is equal to D. Now, obviously these two objects are attracting the one which is at point R because these are two positive and this is negative. So they're opposite, so they're attracting each other. So my question is what is the force which this particular object experiences as a result of these two forces? It's a very simple problem and it basically includes only the Coulomb's law and the law of addition of vectors which represent the forces. So we have basically two forces of attraction. One from P, it goes this way and another is from Q, it goes this way. They are of the same magnitude and the magnitude of each force is this coefficient which is known from the Coulomb's law. The one charge, another charge minus, so minus would be here, Q and minus Q divided by D square which is the square of the distance between them. So this is one force and this is another force, exactly the same magnitude but directed slightly differently, right? So this is an angle of 60 degrees, right? So what is the result of addition of these two forces, these two vectors? Well, there is a parallelogram rule, right? You know, so this is, go this way, this way, this way. So what's the length of, let's put this point A, what's the length of RA? If you know the angle, you know, this is D, this is D, this is also D and D. Well, then obviously the half of this is equal to D times sine of 60, sine of 60 degrees. Sine of 60 degrees, this is 60 degrees or cosine of 30 degrees. So this is this piece, which is half of the force. So you have, the half of the force is equal to F times cosine of 30 or sine of 30, which is square root of 3 divided by 2, but the full force will be twice as big. So it's F times square root of 3, which is minus K, Q square, square root of 3 divided by D square. This is the result. So these two point objects will pull, well, on this particular drawing down, if you wish, but anyway, they will be pulling along the bisector of this angle with this force. Next. So this is basically a very simple exercise of the Coulomb's law. And the law of addition of mechanical forces. Next. Next you have, you have two objects, point objects. Each one has charge Q, but they originally, they are hanging on these threads. But considering they are both charged with the same amount of electricity, both, let's say, positive or both negative, then they will repel each other. So the thread will actually be slightly at angle from the vertical. Now, we obviously considering this on the surface of the Earth or any other planet. So there is a G, which is the acceleration of the free fall. They do have mass, let's consider the same mass and the same charge. So the question is, what is the angle from the vertical? They will deviate. Well, let's just think about this way. What kind of force acts on this one? Well, there is a one force is weight, which is mg. Another force is force of repelling. It goes this way. And the tension of the thread. Now the tension of the thread along the thread can be represented as some of two forces. One is vertical and another is horizontal. So this is the tension thread. Now, if this is electrical force of repelling, now, since this is the equilibrium state, because they're just hanging in the thin air, right? So this force of repelling should be equal to this force, which is the component of the tension. And the same thing with the weight. The weight should be equal and opposite in direction to the force, which is the component, another component, vertical component of the tension, right? So let's say the tension is t. Then this is t times sine phi, right? If this is the angle phi, then this is t times sine of phi. Now, this is the horizontal force and it should be equal to the electrical force. Now electrical force is kq square divided by, well, I didn't really tell you this. This is the given d, d square. Now, as far as the vertical component, this is t times cosine phi and it's supposed to be equal to mg. When I'm talking about equal, I'm talking about magnitude, because the direction is always opposite to each other. Now, we have to find the angle, right? So the simplest thing is just divide this by this and you will have sine divided by cosine, which is tangent of phi, is equal to kq square divided by mg d square. And from this we can define the angle. That's it. Problem number three. Problem number three is let's imagine an atom of hydrogen. So you have a proton plus e and you have electron, which is circulating on an orbit, which is minus e. And let's consider we know its mass. So we know the charge, charge of the proton is equal to the charge of electron, just opposite signs, negative electron, positive for proton. And let's say we know the mass. So my, and one more thing is we know the radius of the atom, atom of hydrogen. Now my question is what is the angular velocity of the electron as it circulates around the proton? And frequency of number of rotations per second, let's say. Okay, how can we determine that? Well, obviously we have to use the Coulomb's law to determine the force, which keeps the electron on its orbit, right? So again, this is f e, which is equal to I'm talking about magnitude. So forget about the sign k. Let's say this is q, which is equal to plus i and minus e is minus q, minus q. So that's the charge of electron, which is equal to the charge of proton. So the atom is neutral. So we have q square divided by r square, right? So this is the Coulomb's law and this is the force which keeps electron on its orbit. Now from the mechanical part from kinematics of rotation we know that the force which is supposed to be the force which keeps the electron on its orbit, it's supposed to be equal to mass times angular acceleration, which is r omega square. If you don't remember this, I would suggest you to refer to the mechanics part of this course where I'm talking about rotation. That's a very simple thing. Basically, that's it. From here, we can determine the angular speed, which is, so k q square divided by m r square and r r cube. And this is omega square. So omega is equal to square root of this. Now in the notes for this lecture, in some cases, like in this one, I actually do some calculations and the calculations based on the numbers which I can get, the real values, what's the mass of electron, what's the charge of electron in Coulomb's, what's the radius of the atom of hydrogen, etc. And I do calculate the final result. What exactly is the number of, what exactly is the angular speed and the number of revolutions per second is omega divided by 2 pi. So if this is the speed, angles, regions per second, if you divide by 2p, it would be number of revolutions per second. That's how many times per second electron is circulating around the nucleus of hydrogen, which is a proton. I just have to make a note here. It's all based on classical Bohr's model of the atom as nucleus and electrons surrounding it. It's not the contemporary view which is based on quantum mechanics, etc. So I'm not going into that. So consider this as just not the reality, how exact how exact the frequency of electron in the hydrogen atom is. It's just this particular model with the numbers which are taken from internet somewhere, all right? So this is the orbital model as it was invented some time ago by Niels Bohr, the physicist. Okay, now this third, that's the force problem now. Force problem also sounds like a real science, but again, it's just our model. The same as the Bohr's model is a model of the atom, whatever I'm doing right now is another problem. It's also kind of a physical abstract, if you wish. So what we are doing is we are trying to bombard some atom with some elementary particle well for the purpose of, let's say, splitting this atom. Now, for instance, whenever we are bombarding uranium 235 with neutrons of certain intensity, it will split and it will be like atomic bomb or it will be more or less regulated reaction if we are regulating the number of neutrons and that can be power station, nuclear power station. Whatever it is, that's the practical side of it. In my case, I'm just kind of making up a problem which sounds similar, but it's not really similar at all. First of all, I'm not bombarding by neutrons but by protons just because I want to have this problem related to Coulomb's law. Why in reality, in the power station, for instance, atoms of uranium are bombarded with neutrons? Well, because neutron is electrically neutral and there is no resistance from the nucleus. Whenever the neutron comes into it, it just goes straight through without any kind of force which prevents to do this type of things. In my case, I want the force, so I want this proton to be bombarding the atom which has n protons. For instance, in case of uranium, you have 92 protons. What's interesting is that as we are bombarding this thing, according to the physics as we know it right now, according to Coulomb's law, the force between these two is inversely proportional to a square of the distance which means that it goes to infinity whenever the distance goes to zero. Now, obviously, this is not a point object. Atom has a certain size and to avoid this type of infinity things, what I'm actually asking is what if I would like this to be covering this distance from A to B. So, I would like to cover the distance from A to B. So, I have initial distance to the nucleus and they have an ending distance to the nucleus. I consider the nucleus to be a point object as well as this proton and what my interest right now is, I would like to know what's my initial speed I have to shoot this proton to cover this distance against the resistance of the nucleus and nucleus is resisting because this is a plus and this is the plus. So, there is a repelling force. So, nucleus is resisting and the force is variable and since the force is variable, I cannot just get to the final result of the calculation. What I do need, I have to divide this into infinitesimal number of little sevens from x to x plus dx. Now, we have even integration, right? So, you do have to know your math. So, we do have to integrate. Now, if it's on this particular place, the force is equal to, as it depends on the x, the force is equal to k times, let's say this is q, this is nq times n times q square, right? q times nq and divided by x square. That's the Coulomb's law. So, I have the force. Okay. Now, if I'm shooting this particular thing, which has certain mass, mass of the proton and certain initial speed, which I don't know yet, I have to find out what's the initial speed. Now, the work which is this particular force is doing when the proton is moving from distance a to distance b is equal to integral from a to b force of x times dx, right? Force times distance. So, this is the work and if I integrate it from a to b, I have the entire work. So, this is exactly the initial kinetic energy of my proton and this is the equation from which I can get the speed, which I don't know yet. So, now, this is equal to integral from a to b, k nq square divided by x square and dx. Now, obviously, this goes outside. So, I have k nq square, integral of x square is 1 over x, right? With a minus sign. So, we'll have 1 over x. So, it's 1 over b minus 1 over a. This is equal to, right? Because the derivative of 1 over x is minus 1 over x square. And so, that's it basically. Now, I have an equation. I have from here I get v is v equals to this thing, which is 2k. This 2 goes there times n times q square times 1 over b minus 1 over a and divided by m and square root of this. And again, I actually substitute certain real values, which I got from the net and I calculate the result of this. So, these are four really very, very simple problems. However, what's important is not only you have to know the Coulomb's law, but also some other things. For instance, how to add the forces, what's the angular acceleration whenever you're talking about the circulating. You have to know some mathematics like simple integrals, like in this particular case. And again, my purpose was not only the Coulomb's law, which is really very simple thing, but also to bring some other pieces from other parts of the course, which you really have to know by now. And if you don't, please go back and refresh your memory. That's it. Thank you very much and good luck.