In order to talk about Inertia we need to go over a little bit of basic physics, this means Newton and his laws of motion. Physics is the study of movement. Everything moves but not everything moves to the same degree. Newton described three laws of motion. Inertia deals with the first law; which is sometimes called the Law of Inertia.
|Our 'artistic' showing of Newton's First Law|
To amend our statement: Objects at rest will stay at rest and and object in motion will stay in motion unless acted upon by another force. So you will keep running in your straight little line until something makes you stop; like a wall.
Inertia can also be explained mathematically (we know, something you'd don't usually want to hear). Don't worry though, the formula for inertia is actually quite easy and you've probably heard of it before.
F = ma"Force equals mass times acceleration." Mass isn't actually the weight of something even though many use the word mass interchangeably with weight. On Earth our weight is an example of Newton's first law and in our case acceleration would be gravity. (It's okay if you don't understand this at first, it is a hard concept.) In physics we show this in kilograms.
Acceleration can be thought of as the speed of something, we show this in meters per second^2 (second squared). So what are the units for force? Kilogram meters per second squared, or otherwise: kg m/s^2. In physics we like to simplify this as a Newton, N, after Isaac Newton of course.
This means that something with a larger mass takes more force to get it moving. You can blow on a feather and get it floating but can you blow on a rock and make it move? This is something that people think about everyday without even noticing. Can we lift that object changing its inertia? If it isn't too heavy we can.
It's amazing how simple things like moving a rock or getting out of bed can boil down to such a simple idea as inertia.
If you want to watch a clip on Inertia here is one we found on YouTube that is helpful. http://youtu.be/by-7kkAu2Pg?t=1m24s