1 (a) 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. This is because pressure acts perpendicular to the surface of the walls.

To calculate the volume of air inside the tube, we can use the formula for pressure and volume relationship:

$P_1 imes V_1 = P_2 imes V_2$

Let:

• $P_1 = 100000 \text{ Pa}$ (atmospheric pressure)
• $V_1 = ?$ (volume of air inside the tube)
• $P_2 = 400000 \text{ Pa}$
• $V_2 = 4.8 \text{ litres} = 4.8 \text{ dm}^3$ (since 1 litre = 1 dm³)

Substituting the given values:

$100000 \times V_1 = 400000 \times 4.8$

Rearranging gives:

$V_1 = \frac{400000 \times 4.8}{100000} = 1.2 \text{ litres}$

The air in the bicycle pump gets warm due to the work done on the air during compression. When the air is compressed, the kinetic energy of the air particles increases, which raises the thermal energy of the system. This process involves converting work into heat. Mathematically, we can express work as:

$W = F \times d$

where $W$ is work done, $F$ is the force applied, and $d$ is the distance over which the force is applied. Since the air is compressed, the energy increases, leading to an increase in temperature.