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(a)(i)Read question and case materials as text
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A student investigates how hot water cools at the top and bottom of a beaker. The room temperature is 22.5 °C. Each trial starts with 200 cm³ of hot water.
Fig. 2.1 shows the apparatus and Fig. 2.2 the thermometer at time0. Record its reading to the nearest 0.5 °C in the missing Table 2.1 cell.
A student investigates how hot water cools at the top and bottom of a beaker. The room temperature is 22.5 °C. Each trial starts with 200 cm³ of hot water.
Fig. 2.1Fig. 2.2
Fig. 2.1 shows the apparatus and Fig. 2.2 the thermometer at time0. Record its reading to the nearest 0.5 °C in the missing Table 2.1 cell.
Table 2.1 — water temperature at top and bottom
time t / min
bulb just below surface / °C
bulb just above bottom / °C
0
…
86.0
3
78.0
77.0
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[1 mark]
(a)(ii)
Explain why the student waits about 30 seconds before the initial hot-water temperature reading.
Answer guidance
Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.
[1 mark]
(b)(i)
Table 2.1 gives top-of-water temperatures at t=0 and t=3 min; use your initial reading from (a)(i) and the printed final 78.0 °C to calculate average cooling rate P_T. Show the decrease/time, give two significant figures and unit.
Answer guidance
Show The result is given, so every step of the reasoning is what earns the marks.
[3 marks]
(b)(ii)
Use the printed bottom-of-water temperatures 86.0 °C and 77.0 °C over 3 min in Table 2.1 to calculate average cooling rate P_B.
Answer guidance
Using You must use the thing it names. An answer that reaches the right value another way may not score.
[1 mark]
(c)(i)
Using your top and bottom cooling rates, suggest why a hot liquid should be stirred before its temperature is measured.
Answer guidance
Using You must use the thing it names. An answer that reaches the right value another way may not score.
[1 mark]
(c)(ii)Read question and case materials as text
Text can be resized with your browser. Refer to the original figures below for diagrams and their layout.
A student investigates how hot water cools at the top and bottom of a beaker. The room temperature is 22.5 °C. Each trial starts with 200 cm³ of hot water.
State one feature of the Fig. 2.1 or Fig. 2.3 apparatus arrangement that helps read the thermometer accurately.
State one feature of the Fig. 2.1 or Fig. 2.3 apparatus arrangement that helps read the thermometer accurately.
Fig. 2.3
Answer guidance
State A short answer. No explanation is needed, and adding one cannot earn extra marks.
[1 mark]
(d)
The cooling experiment is repeated. Suggest one variable to keep constant.
Answer guidance
Suggest More than one answer may be acceptable, so long as it is consistent with the physics.
[1 mark]
(e)
After the thermometer is left in the hot water for 30 minutes, predict the water temperature in °C.
[1 mark]
5054/42/O/N/23Cambridge O Level Physics 5054 · Oct/Nov 2023 · Paper 4 variant 2 · Question 2