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Article abstract: The ancient people of the Americas observed the heavens carefully, and many built structures for observing or measuring the movement of the sun and stars

Early Native American knowledge of the heavens ranged from the complex Mayan calendars to more simple markings of the solstices. Throughout North America, references to the sun, moon, stars, and planets occur in creation accounts and other cultural practices.

In Central America, the Mayan calendar influenced civilizations from 100 b.c.e. to the time of the Spanish Conquest (1519-1697). Guatemalan “daykeepers” still use the original astronomical system for divination. The four extant books, or codices, in the hieroglyphic Mayan...

Science: Gastric juice contains 2.98 g HCL per liter. If a person produces about 2.5 L of...

`Al(OH)_3+3HCl rarr AlCl_3+3H_2O`


So to neutralize 3 HCl moles we need 1 mole of `Al(OH)_3` .


Amount of HCl in 1L of gastric juice `= 2.98g`

Amount of HCl in 2.5L of gastric juice `= 2.98xx2.5 = 7.45g`


So per day a person  will produce 7.45g of HCl.

Molic weight of HCl `= 36.5g/(mol)`


Amount of HCl moles produced per day `= 7.45/36.5`

Amount of HCl moles produced per day `= 0.204`


`Al(OH)_3:HCl = 1:3`


Amount of `Al(OH)_3` moles needed `= 0.204/3 = 0.068`


Molic weight of `Al(OH)_3 = 78g/(mol)`


Weight of `Al(OH)_3` needed to neutralize HCl ` `

`= 0.068xx78`...


Biochemistry is the science dealing with the chemical nature of the bodily processes that occur in all living things. It is the study of how plants, animals, and microbes function at the level of molecules.

Biochemists study the structure and properties of chemical compounds in the cells of living organisms and their role in regulating the chemical processes (collectively called metabolism) that are necessary to life. These chemical processes include transforming simple substances from food into more complex compounds for use by the body, or breaking down complex compounds in food to produce energy. For example, amino acids obtained from food combine to form protein molecules, which are used...

Speech: What are some interesting speech topics for a five minute speech?Fun or serious topic

I always love speeches on political scandal. You would have plenty of ammunition right now. You can talk about the Governor of Illinois trying to sell Obama's Senate seat. Or you can fall back on Thurman or Bird or Spitzer. Then there is Ted Steven's bridge to nowhere. It can be a commentary on the abuse of political power.

Petroleum Notes for the Classroom

this is the material for petroleum

Physics: Child sitting in a tree throws his apple from the height of 4.0 m with a velocity...

For this question, you can use: 

`dy= V_(iy) * t + 1/2at^2`

Now first we shall assign the values needed to solve for the time required. 

`dy` = -4 (direction is down)

`V_iy` = 5m * sin (35) = 2.8679

`a ` = acceleration due to gravity = -9.81m/s^2 (direction is down)

`t ` = time = ?

By substitution, we can now have:

`-4 = 2.8679t - 4.9t^2`

Arranging the equation into standard form:

`4.9x^2 -2.8679x - 4 = 0`


To solve for the value of t, quadratic equation is used.

`x = (-b +-sqrt(b^2 - 4ac))/(2a)`

The two values derived from this equation are -0.657 and 1.24. we will choose the positive time  which is 1.24 seconds.


Quiz: Biology

A simple quiz on biology

Science: What is the order of colors in a rainbow?

A rainbow is made by the reflection and refraction of light that interacts with raindrops.  Depending on how this interaction occurs with your location relative to the sun and the raindrops you may see a primary and even a secondary rainbow.

The interaction that occurs to create the primary rainbow will produce a spectrum of colors in order Red - Orange - Yellow - Green - Blue - Indigo -Violet (ROY G BIV) with Red occuring on the outside edge of the rainbow to Violet occuring on the insdie edge (closest to the center) of the rainbow.

The extra reflection that occurs to produce the secondary rainbow causes the colors to reverse order.  So on the secondary rainbow Red will occur on the inside edge followed by Orange,...






alkylation process invloved in petroleum industry


Quiz: Scientific Method

This is a quiz on the scientific method for middle school students

Secondary enrichment of mineral deposits

Secondary enrichment is a naturally occurring, near-surface process whereby a valuable substance is dissolved, carried downward in solution, and redeposited in a concentrated state. This ore-deposition process is also known as downward enrichment or supergene (literally, “origin from above”) enrichment. secondary enrichment does not create a new and separate mineral deposit; rather, it concentrates and makes more valuable an existing deposit. Some low-grade mineral deposits have been made ore-grade as a result of secondary enrichment.

Science: How can a fish survive in water with the oxygen in it only 4 percent of what...


Solar System Test or Study Guide

This sheet can be used as a test or a study guide.

Science: What is the largest muscle in the human body?

The gluteal muscles are largest. The gluteus minimus and maximus comprise this group. They are your buttocks. A very close second is the bilateral latissimus dorsi muscles which are your "lats". They run more than half way up your back and wrap around laterally (the sides). They connect distally in the hip or coxal area. The gluteals are indeed much thicker and have more mass. Another large muscle group is the adductor group on the anterior thigh and also the quadriceps group which is also on your anterior thigh(front thigh). As you can imagine, the muscles of the legs are very strong inpart because they help to support your weight. The masseter muscles of the bilateral jaws are also very strong, and the strongest of all.

Quiz: Birds

A short quiz on birds and their biology

Identity Theft: Do you think with current technology, people are more susceptible to...

In many ways, new technologies are making it easier for us to fall victim to identity theft.  This is particularly true because of the rise of internet commerce and the increasing use of credit and debit cards.

With the rise of internet commerce, more and more of our personal information is on the internet.  We provide such information, for example, to our banks or to the colleges we attend.  These institutions can be susceptible to being hacked.  If this happens, our identities can be stolen.  This would have been much harder in the days before the internet.

In addition, we have moved away from using things like cash and checks and are using credit and debit cards much more than ever before.  These are more...



Biology is composed of many fields, including microbiology, the study of microscopic organisms such as viruses and bacteria; cytology, the study of cells; embryology, the study of development; genetics, the study of heredity; biochemistry, the study of the chemical structures in living things; morphology, the study of the anatomy of plants and animals; taxonomy, the identification, naming, and classification of organisms; and physiology, the study of how organic systems function and respond to stimulation. Biology often interacts with other...

Physics: What is the formula for pressure?

The formula for pressure is

P = F/A

In this equation, P stands for pressure while F stands for force and A stands for area.  Pressure is typically measured in a unit called the Pascal.

So what this means is that the amount of pressure that is exerted on an area is determined by the size of that area and by the amount of force that is pressing against it.

Therefore, if you have a given amount of force, you will have more pressure if it presses down on a small area than if it presses down on a large area.

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