WAEC Physics 2021 Theory — Question 16
Question 16 of 35 from the West African Examinations Council (WAEC) Physics 2021 Theory paper, with the correct answer and a full explanation.
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9(c). (i) Explain the statement: 'the specific heat capacity of copper is 400 J/kg K'. (ii) Two metals P and Q are supplied the same quantity of heat. If the ratio of the specific heat capacity of P to Q is 3:1 and their masses are in the ratio 1:2, calculate the ratio of the temperature rise of P to Q.
Model answer
(i) It means that 400 Joules of heat energy is required to raise the temperature of 1 kg of copper by 1 Kelvin (1°C). (ii) H=mcΔθ is equal for both (same heat supplied). With Cp=3Cq and Mp=Mq/2: Mp·Cp·Δθp = Mq·Cq·Δθq ⟹ Δθp/Δθq = (Mq·Cq)/(Mp·Cp) = (2×1)/(1×3) = 2:3.
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