Chapter 24, Problem 34A

When you pump a tire with a bicycle pump, the cylinder of the pump becomes hot. Give two reasons why this is so.

To determine

To Give: Two reason for the temperature change of cylinder of the pump.

Explanation of Solution

Introduction:

The First Law of Thermodynamics,

  $\Delta U=Q-W$

Where,

  $\Delta U=$ Internal energy

  $Q=$ Heat

  $W=$ Work done

i.e., the internal energy of a system is depend on the heat and work done of the system. This is based on the conservation law of energy.

In the bicycle pump, a rubber is coated around a piston inside a metal cylinder. When one pulls the handle of pump, then the piston moves in upward direction and when one pushes the handle of pump, the piston moves in downward direction.

During this process a lot of friction force is working between the piston’s rubber and the cylinder and due to this friction force, the cylinder heats up.

In the process, the internal energy of the pump does not change and hence the work done by the pump will raise the temperature.

Conclusion:

Hence, the temperature of pump’s cylinder will increase due to the friction force and work done by the pump.