Question

a ball of mass m is raised to height h and then dropped to the ground .at what height kinetic engergy of the ball is thrice its potential energy?neglect air resistence
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Answer 1

When it hits the floor it has no potential energy, but lots of kinetic energy. Another interesting thing happens when the ball hits the floor. Remember that the ball bounces back up to a height lower than it started, so after one bounce it has less potential energy than it started with.