WAEC Physics 2017 Objective — Question 22

Question 22 of 50 from the West African Examinations Council (WAEC) Physics 2017 Objective paper, with the correct answer and a full explanation.

A solid of mass 0.5kg initially at 50°C melts at 60°C. Calculate the quantity of heat required to melt it completely. [Specific heat capacity of the solid=2.0 KJ kg⁻¹ K⁻¹, Specific latent heat of fusion of solid=1.0KJ kg⁻¹]

A. A. 1500J
B. B. 10000J
C. C. 10500JCorrect
D. D. 15000J

Explanation

Given: mass of the solid=0.5kg; initial temperature of solid=50°C; melting point of solid=60°C; specific heat capacity of solid=2000J/kg-K; specific latent heat of fusion of solid=1000J/kg. Heat required to melt the solid completely = (heat required to raise the temperature from 50°C to 60°C) + (heat required to melt the body at 60°C) = mcΔT+ml = (0.5x2000x(60-50)) + (0.5x1000) = 10,000+500 = 10,500J.

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