When a ball is above the table, the ball has some potential energy and when the ball is dropped from the table to the ground, that potential energy gets converted into kinetic energy.
But where does that energy go when the ball has dropped all the way to the ground? At the ground, the potential energy should be zero because no height and since the ball is not moving, the kinetic energy should also be zero. But according to the law of thermodynamics, “energy cannot be destroyed.” So my question is, where does the energy go when the ball reaches the ground?
In: Chemistry
It gets converted to other forms.:
* heat from friction between the ball and the floor, leaving the ball and floor spot slightly warmer
* heat within the ball from it flexing and deforming on impact, leaving the ball interior slightly warmer
* sound – the sound energy of the ball landing or bouncing
* momentum transfer to the Earth (which doesn’t move it much because it’s a lot heavier than the ball)
When the ball hits the ground (which is the entire earth) it transfers that momentum to the planet earth. The Energy is absorbed by the earth.
Also, some of the energy will her transformed into heat energy due to the molecules of the ball/earth deforming and rubbing and having friction with each other during the collision
Edit: yes, this does mean if you hit earth with a big enough ball you could change its orbit. Conservation of momentum.
When the ball hits the ground, it squishes like a spring, and then bounces back up. It’s not perfect though, so some of the energy gets lost along the way in the form of heat, sound and air resistance. Eventually, all of the energy is dissipated into the environment where you have a few marginally faster air molecules moving around.
You can see how much energy the ball loses with each bounce by looking at how high it gets before falling back down, since in a mathematically perfect scenario of 0% energy loss, it would always just bounce back up to exactly the original table height in an infinite cycle.
What happens when the ball hits the ground?
It dissipates energy as heat, sound, or it bumps into its surroundings, moving them very slight amounts, transferring the kinetic energy to them.
Energy cannot be created or destroyed, but there are many forms of energy it can transform into.
richard feynman – fun to imagine – highly recommended https://www.youtube.com/watch?v=P1ww1IXRfTA
One thing that I think you might be missing is that the potential / kinetic energy equations are all relative to your frame of reference.
In your example, the ground is your 0 point, because you measured from the ground up to the table. Setting your frame of reference so one part of the equation calculates to 0 (or is otherwise easy to simplify) makes is a good choice, but it is completely arbitrary.
If you tweaked your question so that the ground you drop the ball onto is at the top of a hill such that the ball starts rolling after it hits the ground, you may find that using the bottom of the hill as the 0 point for your reference frame makes sense.
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