# Breaking the Law of Conservation of Energy

When a basketball is dropped then bounces up it reaches 0 kinetic energy, but it doesn't reach original height it was dropped from. Why does this not violate the Law of Conservation of Energy?

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berkeman
Mentor
When a basketball is dropped then bounces up it reaches 0 kinetic energy, but it doesn't reach original height it was dropped from. Why does this not violate the Law of Conservation of Energy?
What are your thoughts? We need you to attempt to answer the question before we can offer tutorial help (them's the Rules -- see the link at the top of the page).

It's a fun problem -- that do you think is going on?

I think its because when the ball bounces back up since it has elastic potential energy. But it doesnt reach the same height it was dropped from because it loses kinetic energy and also gravitational potential.

berkeman
Mentor
I think its because when the ball bounces back up since it has elastic potential energy. But it doesnt reach the same height it was dropped from because it loses kinetic energy and also gravitational potential.
Um, no. What different forms of energy are involved in the ball drop and bounce. Think of other forms beyond simple PE and KE...

the only other i can think of is thermal but that's on a very small scale. And its not rotational even though it is a ball. I'm kinda stuck on this question

berkeman
Mentor
the only other i can think of is thermal but that's on a very small scale. And its not rotational even though it is a ball. I'm kinda stuck on this question
Yes there is some thermal energy change involved? What all heats up from the motion and bouncing? What else would be different if you were bouncing the ball in a vacuum?

Im only in Physics not AP. i haven't gotten into depth about things like that. were only in basic. But the teacher said thermal was not a huge factor

ehild
Homework Helper
Do you hear when the ball hits the ground? :)

ehild

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