Question

Explain why, in practice, the pump will generally get hot when pumping up a tyre.

Answer 1

When pumping up a tyre, the new air pumped into the tire compresses the gas that was already in the tire and, as a result, the pressure rises. The molecules of the gas becomes move faster and collides more often with the wall of the pump. As a result, they transfer the energy to the metal wall of the tire and it becomes hot.