Figure 1 shows air inside a cylinder with a movable piston - Edexcel - GCSE Physics - Question 1 - 2018 - Paper 1

The angle that the outward force makes with the wall of the tube is 90 degrees, as the force is perpendicular to the surface of the tube.

To calculate the volume of air inside the tube, we use the equation based on the principles of pressure and volume:

$P_1 \times V_1 = P_2 \times V_2$

Substituting the values:

$400000 \times V_1 = 100000 \times 4.8$

Rearranging the equation, we find:

$V_1 = \frac{100000 \times 4.8}{400000}$

Evaluating this gives:

$V_1 = 1.2 \text{ litres}$

The air in the bicycle pump gets warm due to the work done in compressing the air. When the air is compressed, its kinetic energy increases, thereby raising the thermal energy of the system. This increase in kinetic energy results in a temperature rise, causing the warm air in the pump.