A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically
Downward. If the ground at the base of the cliff is level, which rock hits the ground with the
Greatest speed if there is no air resistance?
A) Rock X
B) Rock Y
C) Rock Z
D) They all hit the ground with the same speed.

Question

Quizplus · Accepted Answer

In the absence of air resistance, all rocks will hit the ground with the same speed due to the conservation of energy. The initial kinetic energy is converted into potential energy (for the rock thrown upwards) and back into kinetic energy, while the rocks thrown horizontally and downwards are affected by gravity in such a way that they all reach the same final speed upon impact.

A Person Stands on the Edge of a Cliff