There are several ways to increase the pressure of the gas below the piston in the cylinder:
1. Lowering the piston: By lowering the piston, the volume of the gas decreases while the number of gas particles remains constant. This decrease in volume leads to an increase in pressure according to Boyle's Law (P1V1 = P2V2).
2. Increasing the number of gas particles: Adding more gas particles to the cylinder will increase the number of collisions between particles and the walls of the cylinder, resulting in an increase in pressure.
3. Increasing the temperature: Increasing the temperature of the gas will cause the gas particles to move faster and collide with the walls of the cylinder more frequently and with greater force, leading to an increase in pressure according to the Ideal Gas Law (PV = nRT).
4. Decreasing the volume of the cylinder: If the volume of the cylinder is reduced, the same amount of gas particles will be confined to a smaller space, resulting in an increase in pressure according to Boyle's Law.
Overall, any action that reduces the volume, increases the number of gas particles, or increases the temperature will result in an increase in the pressure of the gas below the piston.