14. Temperature
A section of Physics, 9702
Listing 10 of 51 questions
Two metal spheres are in thermal equilibrium. State and explain what is meant by thermal equilibrium. An electric water heater contains a tube through which water flows at a constant rate. The water in the tube passes over a heating coil, as shown in . heating coil water out water in tube The water flows into the tube at a temperature of 18 °C. When the power of the heater is 3.8 kW, the temperature of the water at the outlet is 42 °C. The specific heat capacity of water is 4.2 J g–1 K–1. Use the data to calculate the flow rate, in g s–1, of water through the tube. flow rate = g s–1 State and explain whether your answer in is likely to be an overestimate or an underestimate of the flow rate.
9702_w12_qp_42
THEORY
2012
Paper 4, Variant 2
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Two bodies are in thermal equilibrium. State what is meant by thermal equilibrium. The temperature of a body is found to increase from 15.9 °C to 57.2 °C. Determine, in kelvin and to an appropriate number of decimal places, the rise in temperature of the body, temperature rise = K the final temperature. temperature = K An ideal gas at a constant pressure of 1.2 × 105 Pa is heated from a temperature of 290 K to a final temperature of 350 K. The change in volume of the gas is 950 cm3. The total change in kinetic energy ΔEK, measured in joules, of the gas molecules is given by the expression ΔEK = 3 2 × 1.9 × ΔT where ΔT is the change in temperature in kelvin. Determine the thermal energy required to produce the change in temperature from 290 K to 350 K. energy = J
9702_w15_qp_43
THEORY
2015
Paper 4, Variant 3
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State what may be deduced from the difference in the temperatures of two objects, the basic principle by which temperature is measured. By reference to your answer in , explain why two thermometers may not give the same temperature reading for an object. A block of aluminium of mass 670 g is heated at a constant rate of 95 W for 6.0 minutes. The specific heat capacity of aluminium is 910 J kg−1 K− 1. The initial temperature of the block is 24 °C. Assuming that no thermal energy is lost to the surroundings, show that the final temperature of the block is 80 °C. In practice, there are energy losses to the surroundings. The actual variation with time t of the temperature θ of the block is shown in . θ/ °C t / minutes 1. Use the information in to draw, on , a line to represent the temperature of the block, assuming no energy losses to the surroundings. 2. Using , calculate the total energy loss to the surroundings during the heating process. energy loss = J
9702_w17_qp_41
THEORY
2017
Paper 4, Variant 1
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State what may be deduced from the difference in the temperatures of two objects, the basic principle by which temperature is measured. By reference to your answer in , explain why two thermometers may not give the same temperature reading for an object. A block of aluminium of mass 670 g is heated at a constant rate of 95 W for 6.0 minutes. The specific heat capacity of aluminium is 910 J kg−1 K− 1. The initial temperature of the block is 24 °C. Assuming that no thermal energy is lost to the surroundings, show that the final temperature of the block is 80 °C. In practice, there are energy losses to the surroundings. The actual variation with time t of the temperature θ of the block is shown in . θ/ °C t / minutes 1. Use the information in to draw, on , a line to represent the temperature of the block, assuming no energy losses to the surroundings. 2. Using , calculate the total energy loss to the surroundings during the heating process. energy loss = J
9702_w17_qp_43
THEORY
2017
Paper 4, Variant 3
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Define specific latent heat of fusion. A student sets up the apparatus shown in in order to investigate the melting of ice. A V + – heater pure melting ice beaker water The heater is switched on. When the pure ice is melting at a constant rate, the data shown in are collected. voltmeter reading / V ammeter reading / A initial mass of beaker plus water / g final mass of beaker plus water / g time of collection / minutes 12.8 4.60 121.5 185.0 5.00 The specific latent heat of fusion of ice is 332 J g–1. State what is observed by the student that shows that the ice is melting at a constant rate. Use the data in to determine the rate at which 1. thermal energy is transferred to the melting ice, rate = W 2. thermal energy is gained from the surroundings. rate = W
9702_w18_qp_42
THEORY
2018
Paper 4, Variant 2
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State what is meant by specific latent heat. A student determines the specific latent heat of vaporisation of a liquid using the apparatus illustrated in . V pan of balance heater liquid A + – The heater is switched on. When the liquid is boiling at a constant rate, the balance reading is noted at 2.0 minute intervals. After 10 minutes, the current in the heater is reduced and the balance readings are taken for a further 12 minutes. From time 0 to time 10.0 minutes, the mass of liquid evaporated is 56 g. Use to determine the mass of liquid evaporated from time 12.0 minutes to time 22.0 minutes. mass = g Explain why, although the power of the heater is changed, the rate of loss of thermal energy to the surroundings may be assumed to be constant. Determine a value for the specific latent heat of vaporisation L of the liquid. L = J g–1 Calculate the rate at which thermal energy is transferred to the surroundings. rate = W
9702_w19_qp_41
THEORY
2019
Paper 4, Variant 1
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State what is meant by specific latent heat. A student uses the apparatus illustrated in to determine a value for the specific latent heat of fusion of ice. A V beaker melted ice pan of balance heater ice The balance reading measures the mass of the beaker and the melted ice in the beaker. The heater is switched on and pieces of ice at 0 °C are added continuously to the funnel so that the heater is always surrounded by ice. When water drips out of the funnel at a constant rate, the balance reading is noted at 2.0 minute intervals. After 10 minutes, the current in the heater is increased and the balance readings are taken for a further 12 minutes. From time 0 to time 10.0 minutes, 65 g of ice is melted. Use to determine the mass of ice melted from time 12.0 minutes to time 22.0 minutes. mass = g Explain why, although the power of the heater is changed, the rate at which thermal energy is transferred from the surroundings to the ice is constant. Determine a value for the specific latent heat of fusion L of ice. L = J g–1 Calculate the rate at which thermal energy is transferred from the surroundings to the ice. rate = W
9702_w19_qp_42
THEORY
2019
Paper 4, Variant 2
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State what is meant by specific latent heat. A student determines the specific latent heat of vaporisation of a liquid using the apparatus illustrated in . V pan of balance heater liquid A + – The heater is switched on. When the liquid is boiling at a constant rate, the balance reading is noted at 2.0 minute intervals. After 10 minutes, the current in the heater is reduced and the balance readings are taken for a further 12 minutes. From time 0 to time 10.0 minutes, the mass of liquid evaporated is 56 g. Use to determine the mass of liquid evaporated from time 12.0 minutes to time 22.0 minutes. mass = g Explain why, although the power of the heater is changed, the rate of loss of thermal energy to the surroundings may be assumed to be constant. Determine a value for the specific latent heat of vaporisation L of the liquid. L = J g–1 Calculate the rate at which thermal energy is transferred to the surroundings. rate = W
9702_w19_qp_43
THEORY
2019
Paper 4, Variant 3
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Define specific heat capacity. Two solid blocks X and Y are made from different metals. The blocks have different initial temperatures. Block Y is initially at room temperature. The blocks are placed in direct thermal contact with each other at time t = 0. shows the variation with t of the temperatures of the two blocks. 0.5 1.0 1.5 t / min 2.0 2.5 3.0 temperature / °C X Y State three conclusions that may be drawn from . The conclusions may be qualitative or quantitative. The ratio mass of block Y mass of block X is equal to 1.3. The metal in block Y has a specific heat capacity of 901 J kg–1 K–1. Determine the specific heat capacity of the metal in block X. specific heat capacity = J kg–1 K–1
9702_w24_qp_41
THEORY
2024
Paper 4, Variant 1
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Define specific heat capacity. Two solid blocks X and Y are made from different metals. The blocks have different initial temperatures. Block Y is initially at room temperature. The blocks are placed in direct thermal contact with each other at time t = 0. shows the variation with t of the temperatures of the two blocks. 0.5 1.0 1.5 t / min 2.0 2.5 3.0 temperature / °C X Y State three conclusions that may be drawn from . The conclusions may be qualitative or quantitative. The ratio mass of block Y mass of block X is equal to 1.3. The metal in block Y has a specific heat capacity of 901 J kg–1 K–1. Determine the specific heat capacity of the metal in block X. specific heat capacity = J kg–1 K–1
9702_w24_qp_43
THEORY
2024
Paper 4, Variant 3
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Questions Discovered
51