system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: What determines whether an object can bounce or not?

Is the material an object is made out of more important? Or also what material the ball comes into contact with also important? (throwing a ball down on concrete vs throwing it on grass)
gpt
Elasticity.  The material has to deform to convert the kinetic energy of its movement into potential energy in the deformation (like a spring) and then give the energy back to push the object back up.  A high elasticity means that more of the energy that is absorbed by the object deforming comes back out as kinetic energy.  Low elasticity means more of the energy is converted to another form like heat or breaking the internal structure of the object.