Question

During a pool game the cue ball is shot at the red ball. When the cue ball strikes the red ball, the cue ball stops dead, and the red ball moves away at the same velocity the cue ball had before the collision. The type of collision represented in this example is:

• A. An elastic collision
• B. A perfectly inelastic collision
• C. An inelastic collision
• D. All of the above
• E. None of the above

Answer 1

Answer: (A)

An elastic collision

In an elastic collision there is no loss of kinetic energy. If in the given case , balls are of same masses then their kinetic energies will also be same because their velocities are equal and as said , only one ball is moving before and after collision therefore total kinetic energy is constant i.e. it is an elastic collision.

total kinetic energy before collision= total kinetic energy after collision

$1/2m{v}^2+0=0+1/2m{v}^2$