Chapter 15, Problem 105A

Bicycling Describe the energy conversions that occur when a bicyclist coasts down a long grade, then struggles to ascend a steep grade.

Interpretation Introduction

Interpretation:

The energy conversions that occurs when a bicyclist coasts down a long grade, then struggles to ascend a steep grade needs to be explained.

Concept introduction:

Potential energy is energy due to the composition or position of an object. Kinetic energy is the energy produced due to motion.

Answer to Problem 105A

Potential energy is converted to kinetic energy.

Explanation of Solution

The cyclist is working with gravity.

When the bicyclist coast down a long grade, bicyclist doesn’t need to pedal as the gravitational force pulls the bicyclist.

Hence the potential energy gets converted to kinetic energy.

While, when the cyclist is going up, the cyclist need to pedal, which means the cyclist is burning energy from his body. Here, chemical potential energy converts to mechanical energy to make cyclist able to turn the pedal. The mechanical energy is then converted to kinetic energy.

Conclusion

Thus, on moving something, chemical potential energy is used and energy burns within the body.