Question

When you use a hand pump to inflate the tires of your bicycle, the pump gets warm after a while. Why? What happens to the temperature of the air in the pump as you compress it? Why does this happen? When you raise the pump handle to draw outside air into the pump, what happens to the temperature of the air taken in? Again, why does this happen?

Short answer

The work done on the system when we use a hand pump to inflate the tires of our bicycle will increase the internal energy of the system, hence the temperature.

Step-by-step solution

About the Adiabatic process and its impact.

When we use a hand pump to inflate the tires of our bicycle, the pump gets warm after a while. This process is adiabatic, so there is no heat exchange. Therefore, the work done on the system will increase the internal energy of the system.

In an adiabatic process, there is no heat exchange

$∆\underset{~}{O}=0$

According to the first law of thermodynamics

$∆\underset{~}{O}=∆U+W$

Hence, we get

$$\begin{gathered} 0=∆U+W \\ W=-∆U \end{gathered}$$

Conclusion

$∆U=-W$

Therefore, there is an increase in temperature because of the increase in the internal energy of the system.