You probably have most of this stuff at home anyway

4.1 Introduction to Linear Momentum

Key ideas:

  • Linear momentum is a vector

  • Momentum is equal to mass x velocity

  • Linear Momentum is conserved

Textbook:  Chapter 7, but we will be skipping 7-7 and 7-9

Introduction:

Momentum = mass x velocity.  Sounds easy, right?

In the previous module on conservation of energy, I said that there were two great conservation laws that govern all of physics.  Conservation of energy is one of them.  Conservation of momentum is the other.  We studied energy first, because it's the easier one.

Momentum is a little harder because it's a vector.  In the case of energy, it was scalar.  To get the total energy, you just added the various energy components together.  No need to worry about left or right or up or down.  Unfortunately momentum actually has six components, although we will only be looking at three of them in this module.  They are:

x-momentum

y-momentum

z-momentum

Notice that we use the letter 'p' for momentum.  Remember how we dealt with two dimensional motion before?  You handle one dimension at a time, and you use vector components.  To make your life a bit easier, we will do a lot of problems that only involve one dimension.  However, if you're still a little unsure of yourself when working with vectors and components, you might want to review that section as necessary.