Lesson 14: How Bearings Increase Efficiency (How Things Work)

In this lesson, we will analyze how rolling element bearings aid mechanical components and increase efficiency by reducing friction. These rolling element bearings are found in almost every mechanical device which involves rotation. They are found in cars, carts, windmills, and even yo-yo's.

These bearings function on the principal that it is easier to roll something as opposed to slide something. To verify this, take something flat like a book and push it across a flat surface such as a table. Note how much force is required to push the book. Then place the book on a few cylindrical or spherical objects such as marbles or pencils. Now push the book and notice how much easier the book moves.

When objects slide across surfaces, the force of friction resists e object's motion. However, when something rolls, there is relatively no sliding occurring, so the resistant force of friction is minimized.

Rolling element bearings exploit this fact by placing round objects between two surfaces which would normally come in contact with each other with sliding motion. The inner surface of a rolling element bearing is known as the inner race while the outer surface is known as the outer race. The rolling elements are usually kept separated to reduce sliding with one another by a metallic structure called a cage.

Below is a picture of what a rolling element bearing might look like.

Lesson 13: How a Light Bulb Works (How Things Work)

Most people forget that at night, the light they enjoy is made possible by the invention of the light bulb. I thought, for our first lesson in how stuff works, we could analyze something relatively simple, but very important in our everyday lives.

Most people know that a light bulb requires power to function, and as a result, it outputs light and a little bit of heat. However, a significant portion of people do not know how this power is converted into light and heat, so today, we will discuss the mechanisms which make the light bulb work.

In a light bulb, there is a very thin wire usually made out of tungsten which is called the filament. When electrical current is passed through this filament, resistance is created. In our house, the wires connecting electrical appliances are relatively thick so the electricity can pass through them easily. When this current passes through the thin filament the electricity is forced through a small, thin path. Think of a crowd of people trying to fit through a small door all at once. This is called Resistance which causes the filament to burn.

In the light bulb, there is no gas, this is called a vacuum. This vacuum prevents the filament from oxidizing or destroying itself when electrical current is passed through it. This in turn keeps the filament white hot, which provides the light we use every night.

We have all had experiences with hot light bulbs, usually ending up in discomfort or burns. This heat can be thought of as inefficiency. When turning on a light bulb, we only want to light our house, not heat it, so this heat is a loss of energy and is inefficient. Currently, light emitting diodes, or LEDs, which are a type of light, put off very little heat and can be very bright for the amount of current passed through them. These are thought of as highly efficient lights and are being used in more and more applications.

For more information on light bulbs, check out:

1. http://en.wikipedia.org/wiki/Light_bulb
2. http://www.ideafinder.com/history/inventions/lightbulb.htm

Lesson 12: Chemical Reaction Equations (Chemistry)

In this lesson, we will discuss the equations which are used to describe chemical reactions. These are a vital part of the study of chemistry because the equations illustrate how substances react and what the reaction produces. Don't worry thought, these equations are extremely easy to understand and only simple math is required to work with them at this point.

An example of a reaction equation would look like this: 2H2 + O2 --> 2H20.

This is a relatively simple equation which describes hydrogen burning in the presence of oxygen to form water. In the reaction equation, the --> can be thought of as saying "reacts to form". The components on the left of the --> are the ingredients of the reaction which are called the reactants. The reactants interact to form the components on the right of the --> which are called the products.

In reaction equations, there are two types of numbers involved, coefficients and subscripts. The coefficients, like the first 2 in both 2H2 and 2H2O, are used to balance the reaction equation so the number of atoms on the right side of the equation will equal the number of atoms on the left side of the equation. Think of the coefficients as saying 2 H2 molecules or 2 H2O molecules. This is necessary because we know matter can not be created or destroyed so an unbalanced equation does not accurately depict a legitimate chemical reaction.

Due to text limitations in blogger, think of the second 2 in 2H2 and 2H2O and the 2 in O2 as being subscripts or small numbers located near the bottom of the line. These represent multiple atoms bound to another atom. Think of the molecule H2O. There are two hydrogen atoms bound to the oxygen atom. Subscripts can be thought of as numbers which tell us how the molecules involved in the reactions are constructed as opposed to how many of those molecules are involved in the reaction.

Reaction equations are used to predict not only what products will be produced from a reaction, but how much of those products will be produced. In the following equation, Mg + 2Cl --> MgCl2, we know, if we put in 100 atoms of Mg and 200 atoms of Cl, we will receive 100 atoms of MgCl2. Chemists do not calculate exactly how many atoms are used and will be formed, but rather, the measurement of mols is used in conjunction with chemical reaction equations. We will cover this in later lessons.

More information on chemical reaction equations can be found at:

1. http://en.wikipedia.org/wiki/Chemical_equation
2. http://www.science.uwaterloo.ca/~cchieh/cact/c120/reaction.html

The second link is helpful but covers topics that we have not yet discussed so if you aren't sure what is going on, don't worry, we will cover it in later lessons.

Lesson 11: The Periodic Table

In the previous lesson, we learned about the construction and composition of atoms, so in this lesson, we will learn how to read the periodic table of elements which is a Chemist's most important tool. This table, depending on how detailed it is, gives readily used information needed for calculations in chemistry.

Due to the complexity of the table, I won't draw one, but rather provide you with links to various tables. The former link leads to a basic table coupled with large amounts of additional. The latter link offers a very detailed table which would be more useful in more complex chemistry.

1. http://en.wikipedia.org/wiki/Periodic_table
2. http://www.dayah.com/periodic/

In this table, each element is represented by an abbreviation of one, two, or three letters. Some abbreviations correlate with the name of the element, such a C for carbon, but some represent Latin elemental names such as pb for lead.

Typically above each abbreviation is some whole number. This is called the atomic number and represents the number of protons in the nucleus of the atom. This number also represents the number of electrons in the atom if it the atom has an overall charge of zero.

The number below the abbreviation which is a number with some decimal is the average atomic weight of the atom. This number is the mass of the different isotopes for the element averaged together in terms of their abundances. Recall that from our last lesson, we established that one element is capable of having atoms of different masses because the atoms can have different amounts of neutrons. This number is used when the number of mols of atoms is being converted to mass. We will cover this more in detail later.

This table expresses many more traits of the elements being represented and we will cover these as we progress.

If you find this interesting, feel free to try to memorize the elements and associate them with their abbreviations. In chemistry the atomic abbreviations come up frequently so memorization would speed things up down the road. Otherwise, for occasional, casual chemistry, a periodic table can be referred to for abbreviations and elements.

Lesson 10: Composition of Atoms and Their Charge

Since we have been covering a lot of physics and math, why don't we try a few lessons in Chemistry. Before we can delve very far into the study, a basic knowledge of atoms and their components is required. So today, we will learn about how atoms are constructed, what each component of an atom is, and the charge of each of these components.

Atoms are comprised of 3 components. They are protons, neutrons, and electrons. So, to get a better understanding of what these are and what their function is, let's go through a description of each one.

1. Protons - These are located in the small nucleus of the atom along with the neutrons. They have a charge of +1. In order to remember this charge, it is often helpful to associate proton with the word positive. Protons, along with neutrons are relatively heavy particles.
2. Neutrons - These particles are also located in the nucleus of the atom along with the protons. These particles have no charge but a significant mass.
3. Electrons - These are particles with very little mass and are located in orbit around the nucleus. They move so fast that they can be thought of as forming a cloud around the nucleus. This is often referred to as the electron cloud. Electrons have a charge of -1.

It is important to remember that in a neutrally charged atom, there are as many electrons as there are protons. Think of this as adding all the individual charges up which will sum up to 0. However, the amount of neutrons can be different, even within the same type of element. Isotopes are atoms with a consistent amount of protons and electrons, but with different amounts of neutrons.

With this understanding of how atoms are constructed, we are prepared to learn about how they interact and bond to each other.

For more information, check out the following link: http://en.wikipedia.org/wiki/Atomic_structure

Lesson 9: Right Triangles and the Pythagorean Theorem

So far, we have covered a lot of physics so today, I thought we would look into a little math, more specifically, trigonometry. You might be asking why we are covering this or even why triangles are so important in the first place. The reason is, most geometric shapes can be broken down into numerous triangles for easier calculations which makes everyone's life a little easier. Think of a hexagon, square, octagon. These shapes occur frequently and can be broken down into individual triangles. Additionally, a lot of higher math and physics require vector analysis which requires a substantial amount of trigonometry.

The most basic type of triangle is called the right triangle. Its name states that the triangle contains one right angle which is a 90 degree angle. These types of triangles are the easiest to work with due to the fact that they correlate with simple formulas. Today we will discuss the Pythagorean Theorem. This is an equation which will give us the length of a third side when the lengths of the other two are inserted.

The formula is C^2 = A^2+B^2. C is the length of the hypotenuse of the triangle, which is the longest side, and A and B are the lengths of the other two sides. In order to use this formula, we would plug in the lengths of the two sides that we know and solve for the third.

Lets go through an example so you can get the hang of how this formula works. Let's say we have a triangle with two smaller sides with the lengths of 3 meters and 4 meters. We would plug these values in to get. C^2=(3)^2+(4)^2. We then have 9+16 which is equal to 25. We still have C^2 and we want C so we would take the square root of both sides to get C=5. Now we know the lengths of all of the sides of the triangle in question.

This theorem is extremely useful, and can be applied across a wide variety of applications such as finding the length of diagonal poles needed to make a tent or finding if a square is truly square (if both diagonals inside the square are equal in length).

So, make up a few measurements and try this formula out for yourself. It is relatively simple so you should get the hang of it quickly. If you have any questions just leave a comment and I will reply promptly.

For more information, check out http://en.wikipedia.org/wiki/Pythagorean_theorem

Lesson 8: Compound Units

In our previous chapter, we discussed the seven basic units which are the building blocks of all the units imaginable. They decribe quantities which can not be broken down any further such as length or time.

In this chapter, we will cover compound units which are comprised of combinations of basic units. These include things such as velocity, acceleration, force, energy and more.

There are way too many compound units to cover in this lesson so we will just go over a few so you can get an understanding and feel for them and you can apply this understanding to other compound units you may encounter in the future.

So lets start off with a simple compound unit, speed. It is represented as distance/time. In the metric system it is typically expressed as meters/second. So we have one unit divided by the other. This can be thought of as x many units of length will be traveled in y many units of time. Typically the numbers are arranged so the units on the bottom are equal to 1 and fractional values can be eliminated to simplify calculations. As an example, lets assume we have a value of 50 m/s. This means 50 meters will be traveled in 1 second.

Now, lets try a more difficult compound unit, force. This is expressed as (mass * length)/time squared. In the meteric system this is usually expressed as (kilogram * meters)/second squared, which is known as a Newton. Don't get scared here, we will jsut apply the same concepts that we used in the previous example. We can break this down into seperate components. Meters/second squared is acceleration, so we know that units of force is just mass * acceleration. So if we had a force of 50 Newtons and an object with a mass of 1 kg, it would recieve an acceleration of 50 meters per second.

Does this make sense? Basically, we are just breaking down the compound units into thier basic unit components to analyze what is really occuring. So take a few minutes and think of a few other compound units and try to break them down to see what they really describe. If you are having trouble, don't worry at all, this is no easy task to perform.

For additional information, check out: http://www.sciencemadesimple.net/units.html
This is a huge list of units which stretches on for pages.
Additionally, check out: http://www.unc.edu/~rowlett/units/
This is a unit dictionary.