Using momentum to deal with collisions; the center of mass

Momentum turns out to be enormously useful in solving problems which involve collisions, even when you don't know the details. Why? Because under very common circumstances, the total momentum of a set of colliding objects will be the same before and after they collide; in other words, momentum is conserved.

• A very simple example of momentum
• Truck collides with minivan

  Let's work a few examples to get some practice:

• Car slams into truck, and they stick together
• Car rolls into truck but bounces off gently
• Car rolls into truck but bounces off gently (again)
• Car and minivan run into each other
• Hockey puck slides into brick
• Hockey puck slides into brick (again)

  If you want to analyze a real collision, try this:

• Video analysis of colliding carts

When several objects collide or a single object explodes, the individual pieces may fly all over the place. However, if one considers all the pieces as a whole, via the total mass and motion of the center of mass, then Newton's Laws are simple and easy to solve again.

• The connection between the center of mass and momentum in a collision
• How to define the center of mass for a set of little balls

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.