Why does a bicycle pump become hot when it pumps air in a bicycle tube?

Explanation

The pumping operation is very rapid. So, it is essentially an adiabatic compression. Then, Q = 0, and W is negative. From the first law of thermodynamics.
`U_(f)-U_(i) = Q - W = 0 - W or, W = U_(i) - U_(f)`
As W is negative, `U_(i)-U_(f) < 0 or, U_(i) < U_(f)`. so, the internal energy of air increases.
As a result, the temperature also increases and the pump becomes hot.