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.

Explanation:

The law of conservation of energy states that energy cannot be created or destroyed, only transformed.

• Option A: Energy doesn't disappear, so this is wrong.
• Option B: A rolling skateboard slows down as kinetic energy transforms to heat (due to friction), which follows the law.
• Option C: Energy isn't destroyed, so this is wrong.
• Option D: The ramp doesn't create energy (energy is transformed from potential to kinetic), so this is wrong.

Answer:

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