Question

You want to close an open door by throwing either a 400 g lump of clay or a 400 g rubber ball toward it. You can throw either object with the same speed, but they are different in that the rubber ball bounces off the door while the clay just sticks to the door. Which projectile will be more likely to close the door?

Options:

OPTION 1: Clay
OPTION 2: Rubber ball
OPTION 3: Both equally likely
OPTION 4: Not enough information to determine

Answer 1

A rubber ball is more likely to close the door than a lump of clay because it bounces back, which results in a greater change in momentum and greater impact on the door.

Step-by-step explanation:

The projectile more likely to close the door is the rubber ball. When a rubber ball hits an object, it bounces back, which means its velocity changes direction while it maintains a significant amount of its kinetic energy. This change in velocity upon collision means the rubber ball exerts a greater change in momentum on the door compared to the clay, which sticks and transfers less momentum. Momentum is characterized not just by mass and velocity but also by the change in velocity. The rubber ball bounces back with nearly the same speed it had before the collision, but in the opposite direction, meaning there is a larger change in velocity and, consequently, more momentum transferred to the door.