# Worksheet: Elasticity of Collisions

In this worksheet, we will practice distinguishing between the effects of collisions which do and which do not conserve kinetic energy.

Q1:

A ball bounces repeatedly, dissipating of its kinetic energy with each bounce.

Which of the lines plotted on the graph correctly represents the change in the mechanical energy of the ball with time?

• ALine I
• BLine ll
• CLine lll

Q2:

Two objects, I and II, collide. Object I has a mass of 1.2 kg and object II has a mass of 0.75 kg. Object I has a speed of 1.4 m/s before the collision and object II has a speed of 1.8 m/s before the collision. After the collision, object II has a speed of 2.1 m/s.

If the collision is perfectly elastic, what is the speed of object I after the collision?

If the collision is not perfectly elastic, what must the speed of object I after the collision be less than?

If the collision is not perfectly elastic, what is the minimum value of the speed of object I after the collision?

Q3:

Two objects, I and II, collide. Object I has a mass of 0.25 kg and object II has a mass of 0.45 kg. Object I has a speed of 2.8 m/s before the collision and object II has a speed of 3.3 m/s before the collision. The collision is inelastic, dissipating 35% of the kinetic energy of the objects. After the collision, object I has a speed of 1.8 m/s.

What is the speed of object II after the collision?

What is the ratio of the kinetic energy of object I before the collision to its kinetic energy after the collision?

What is the ratio of the kinetic energy of object II before the collision to its kinetic energy after the collision?