4.28 Law of Conservation of Momentum
4.28 Law of Conservation of Momentum
- State the law of conservation of momentum.
- Describe an example of momentum being transferred and conserved.
These skaters are racing each other at Newton’s Skate Park. The first skater in line, the one on the left, is distracted
by something he sees. He starts to slow down without realizing it. The skater behind him isn’t paying attention and
keeps skating at the same speed.
Q: Can you guess what happens next?
A: Skater 2 runs into skater 1.
Conserving Momentum
When skater 2 runs into skater 1, he’s going faster than skater 1 so he has more momentum. Momentumis a
property of a moving object that makes it hard to stop. It’s a product of the object’s mass and velocity. At the
moment of the collision, skater 2 transfers some of his momentum to skater 1, who shoots forward when skater 2
runs into him. Whenever an action and reaction such as this occur, momentum is transferred from one object to the
other. However, the combined momentum of the objects remains the same. In other words, momentum is conserved.
This is thelaw of conservation of momentum.
Modeling Momentum
TheFigure4.52 shows how momentum is conserved in the two colliding skaters. The total momentum is the same
after the collision as it was before. However, after the collision, skater 1 has more momentum and skater 2 has less