Figure 16 shows a metal container with a movable piston - Edexcel - GCSE Physics - Question 7 - 2020 - Paper 1
Question 7
Figure 16 shows a metal container with a movable piston.
Point X is on the inner surface of the container.
The gas in the container is at a higher pressure than th... show full transcript
Worked Solution & Example Answer:Figure 16 shows a metal container with a movable piston - Edexcel - GCSE Physics - Question 7 - 2020 - Paper 1
Step 1
Which of these shows the direction of the force, due to the gas, on the container at point X?
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Answer
The correct choice is option C, as it indicates that the force due to the gas is exerted perpendicular to the surface of the container at point X.
Step 2
Calculate the new pressure of the gas, P₂:
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Answer
Using the equation
P2=V2P1×V1
Substituting the values:
P₁ = 120 kPa
V₁ = 2500 cm³
V₂ = 1600 cm³
The calculation is:
P2=1600cm3120kPa×2500cm3
Upon evaluation:
P2=187.5kPa
Step 3
Calculate the pressure, in N/cm², of the piston on the air in the bicycle pump.
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Answer
Using the formula for pressure:
P=AF
Where:
F = 28 N (force applied)
A = 2 cm² (area of the piston)
Substituting the values, we get:
P=2cm228N=14N/cm2
Step 4
Explain, in terms of the movement of particles, why there is a pressure on the container and why the pressure changes as shown in Figure 18.
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Answer
The pressure inside the container arises from gas particles colliding with the walls of the container. Each collision exerts a force on the walls, contributing to the overall pressure. When the volume of the gas is increased, the particles have more space to move, leading to fewer collisions with the walls, which decreases the pressure. Conversely, as the volume decreases, the frequency of collisions increases, resulting in higher pressure. This relationship is not linear, as indicated in the graph, due to the nature of particle motion and interactions.
