Question

Neglecting air resistance, Sammy Smarts on a high ladder releases a ball that strikes the ground with 100 J of kinetic energy. If he were to instead throw the ball straight upward, it will soon reach the ground with a kinetic energy of ________.

Answer 1

When a ball is thrown straight upward, the amount of kinetic energy it will have when it reaches the ground again will be the same as when it was thrown upward.

Step-by-step explanation:

When a ball is thrown straight upward, its initial kinetic energy is converted into potential energy as it reaches the highest point of its trajectory. At this point, the ball has no kinetic energy. As it falls back down towards the ground, the potential energy is converted back into kinetic energy, so when it reaches the ground again, it will have the same amount of kinetic energy as it did when it was thrown upward.

In this case, since the ball struck the ground with 100 J of kinetic energy when dropped, if it were thrown straight upward and reached the ground again, it would also have 100 J of kinetic energy.