2. Thermal physics
A section of Physics, 5054
Listing 10 of 446 questions
A fixed mass of gas in a glass tube is trapped by a seal at one end of the tube and by a column of mercury. The mercury is free to move within the tube. The tube is rotated slowly from the vertical as shown in to the horizontal as shown in . The volume of the gas increases and its temperature remains constant. mercury mercury gas gas 0.30 m sealed end sealed end (not to scale) Describe why rotating the tube changes the pressure of the gas in the sealed end. Explain, using ideas about particles, why the pressure of the gas decreases when its volume increases. In the length of the mercury column is 0.30 m. The density of mercury is 14 000 kg / m3. Atmospheric pressure is 1.0 × 105 Pa. Calculate the pressure of the gas in the tube. pressure = Pa (not to scale) The pressure of a different sample of gas changes at constant temperature. shows one point, marked X, on a graph of pressure against volume for the gas sample. At X the pressure of the gas is P0 and its volume is V0. 2P0 P0 ½P0 ½V0 V0 2V0 volume pressure X On , sketch the graph as the pressure of the gas decreases from 2P0 to ½P0.
5054_s23_qp_22
THEORY
2023
Paper 2, Variant 2
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A car has a gas-filled shock absorber for each of its four wheels. shows one of these shock absorbers. attached to car body trapped gas piston cylinder axle The axles are attached to the cylinders. The body of the car is supported by the four pistons, which can move up and down inside the cylinders. Each piston has a cross-sectional area of 35 cm2. A driver of mass 70 kg gets into the car. Calculate the driver’s weight, weight = the average increase in the pressure of the gas in the cylinders. pressure increase = Explain in detail how the molecules of the gas trapped inside the cylinder by the piston exert a pressure on the cylinder. The temperature of the trapped gas remains constant. Explain why the pressure of the gas increases as the piston is moved further into the cylinder. At the end of a long journey, the temperature of the trapped gas in the shock absorbers has increased substantially. State what happens to the molecules of the trapped gas due to the temperature increase. State and explain the effect of the increased temperature of the gas on the height of the car body above the road surface.
5054_w10_qp_21
THEORY
2010
Paper 2, Variant 1
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Questions Discovered
446