Physics (AS & A Level) · Feb / March 2016 · Paper 42 · Question 3
9702
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3(a)[2]
the (thermal) energy per unit mass to raise the temperature of a substance by one degree [2]
(If ratio not clear for M1 mark, allow 1 / 2 marks for an otherwise correct answer)
3(b)(i)[1]
to allow for / determine / cancel heat transfer to / from tube / surroundings [1]
(do not allow ‘to stop / prevent’ heat loss)
3(b)(ii)[3]
either P = mc∆θ ± h or 44.9 = 1.58 × 10–3 × c × (25.5 – 19.5) ± h or 33.3 = 1.11 × 10–3 × c × (25.5 – 19.5) ± h (44.9 – 33.3) = (1.58 – 1.11) × 10–3 × c × (25.5 – 19.5) c = 4100 (4110) J kg–1 K–1 [3]
(allow 1 / 3 for use of only 33.3 W, 1.11 g s–1 leading to 5000 J kg –1 K –1) (allow 1 / 3 for use of only 44.9 W, 1.58 g s–1 leading to 4740 J kg –1 K –1)
3(c)[3]
V0 = 27 or Vrms = 19.1 33.3 = 272 / 2R or 33.3 = 19.12 / R R = 11 Ω [3]
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