A person on the edge of a roof throws a piece of tile downward that strikes the ground with 100 J of kinetic energy. Another identical tile is thrown upward with the same initial speed, and this too falls to the ground. Neglecting air resistance, the second tile hits the ground with a kinetic energy of

Question

Quizplus · Accepted Answer

Since both tiles are identical and thrown with the same initial speed, they will have the same initial gravitational potential energy. Therefore, the first tile loses all its initial potential energy (which is equal to its initial kinetic energy) as it falls to the ground, resulting in a kinetic energy of 100 J at impact. On the other hand, when the second tile is thrown upward, it gains some initial potential energy which is then converted to kinetic energy as it falls back down. However, since energy is conserved, the sum of its initial potential and final kinetic energy must also be equal to 100 J. Thus, the second tile will also hit the ground with a kinetic energy of 100 J. Therefore, the answer is B.

A Person on the Edge of a Roof Throws a Piece