Physics Momentum & Collisions

A person standing on a stationary skateboard steps off, causing the skateboard to roll backward across the floor. Describe the momentum of the skateboard before and after the person stepped off.

Before: the total momentum is zero After: the momentum of the skateboard is equal and opposite to the momentum of the person

Two swimmers relax close together on air mattresses in a pool. One swimmer's mass is 48kg, and the other's mass is 55kg. The swimmers push away from each other. a. Describe the momentum of each before and after they push apart. b. Describe the total momentum of the swimmers before and after they push apart.

a. Before: the momentum of the swimmers is zero After: the momentums of each are equal and opposite to each other's b. the total momentum of the entire scenario is zero

Two balls of dough collide and stick together. Identify the type of collision. What happens to the total momentum in this system? What happens to the total kinetic energy in the system?

a. perfectly inelastic collision b. total momentum is conserved c. total kinetic energy is dissipated because it is not conserved

A fast moving rock and a slower moving rock have the same momentum. a. Which rock has more mass? b. Which rock has more kinetic energy? c. Which is harder to stop? Explain in terms of momentum, force, and energy.

a. the slow rock has more mass b. the fast rock has more kinetic energy c. the fast rock is harder to stop

What are some evidences you might observe indicating a collision was not perfectly elastic?

sound, heat, light, permanent deformation, energy discharge

What happens to the total momentum of two bodies after a two-body collision if the kinetic energy of the system is conserved?

the total momentum is conserved