Answer:
When Sue pumps up a bicycle tire, she increases the pressure inside the tire. This increase in pressure is due to the behavior of gas molecules inside the tire.
Inside the tire, there is a higher concentration of gas molecules compared to the surrounding atmosphere. As Sue pumps air into the tire, she increases the number of gas molecules inside, leading to a higher density of gas particles.
The gas molecules are in constant motion and collide with the walls of the tire. With an increase in the number of gas molecules and their velocity due to compression, the frequency and force of these collisions also increase. As a result, the gas molecules exert pressure on the walls of the tire.
The pumping action compresses the gas, which increases the kinetic energy of the gas molecules. According to the kinetic theory of gases, an increase in kinetic energy leads to an increase in temperature. Therefore, as Sue pumps up the tire and compresses the gas inside, the increase in pressure causes the gas molecules to gain more kinetic energy and consequently generate heat. This is why the pump becomes hot during the process of inflating the tire.
In summary, the pressure exerted by the gas molecules inside the tire is a result of their constant collisions with the tire walls, and this increased pressure leads to the generation of heat as the gas molecules gain kinetic energy.
Step-by-step explanation: