Question

Which is the best example of the law of conservation of energy?

A basketball stops bouncing because its energy disappears.
A rolling skateboard slows down because some of its kinetic energy changes to heat.
A falling book hits the ground and all of its energy is destroyed.
A toy car gains speed as it moves down a ramp because the ramp creates energy.

Answer 1

"A rolling skateboard slows down because some of its kinetic energy changes to heat."

This shows energy being transformed (kinetic → thermal) rather than created or destroyed, which is what the conservation of energy states. The other choices claim energy disappears, is destroyed, or is created, which violate the law.