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.