Answer:
When a bouncing ball falls, it initially gains speed or kinetic energy—the energy of motion. When it reaches Earth, it collides head-on with an incredibly massive object that is, from your perspective, at rest. The ball slows down, deforms temporarily and shoots back up. The air in the ball acts like a spring—it gets compressed and expands again. During the collision, some of the ball's energy is converted into heat. As a consequence, the ball shoots up with less energy than it had when it reached Earth. Our planet, being so massive, does not move as a result of the collision.
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