Chapter 4.3, Problem 28R

To determine

To describe: the energy transformation that occurs on coming down a hill on a bicycle and when the brakes are applied to make the bike stop at the bottom, using the law of conservation of energy.

Explanation of Solution

Introduction:The law of conservation of energystates that energy creation or destruction is impossible. Energy can only be transformed from one form to another or transferred from one place to another.

For a bicycle coming down a long hill, due to its height above the ground it has high gravitational potential energy at the top of the hill. While coming downhill this potential energy changes to kinetic energy due to motion. So the potential energy decrease and kinetic energy increases. When the brakes are applied to stop the bike, the kinetic energy is transformed into thermal energy as the brakes rub against the bicycle’s wheels and the bike stops. Thus, holding the law of conservation of energy true.

Conclusion: On coming downhill gravitational potential energy of a bicycle changes to kinetic energy which then transform into thermal energy when the brakes are applied.