A heavy cylindrical piston in a high-pressure laboratory chamber rests on trapped gas. The piston exerts a pressure of 240 kPa240\text{ kPa}240 kPa on the gas.
The cross-sectional area of the piston in contact with the gas is 0.0075 m20.0075\text{ m}^20.0075 m2.
(i) State the equation linking pressure, force, and area.
(ii) Calculate the force exerted on the gas by the piston. Give the unit.
Use ideas about molecules to explain why the trapped gas exerts pressure on the piston and the inside walls of the cylinder.
Additional gas is pumped into the cylinder and the system is heated, while keeping the piston locked in a fixed position. This increases both the number of molecules and the temperature of the gas. Use ideas about molecules to explain why the pressure of the gas increases.