Why does the bottom of a tire pump feel hot when you pump

Solution 9E Step 1: Consider we are pumping up the air by using an air pump. Actually, what we are doing We are compressing the air by using the air pump so, the motion of the air molecules is restricted. So, it will throw out its excess energy into the surroundings as a part of the compression process. The internal energy of this system will be decreased since the air molecules are loosing its excess energy. So, this energy transfer will take place as heat transfer from compressed air molecules to the wall of the container. Only bottom part is getting heated up because, the compressed air will come in contact with the wall of the air pump container at the bottom level only. So, the bottom portion of air pump will be heated up and this heat will be dissipated to the surroundings.