Momentum
Collision carts
Compare momentum and kinetic energy before and after a collision.
m1u1 + m2u2
Apparatus
- Two carts
- A track
- A switch for a sticking or an elastic collision
Method
- Set both masses and both velocities. Right is positive.
- Run a sticking collision first and read the shared velocity.
- Check that total momentum matches, and that kinetic energy has fallen.
- Switch to elastic and run again. Kinetic energy should now match as well.
On a real air track, keep fingers off the moving carts.
1
2
Momentum before
2kg m/s
Momentum now
2kg m/s
KE before
2J
KE now
2J
Collision
Momentum conserved both ways. Kinetic energy conserved only in the elastic case.
Back to the Momentum lesson