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N.B. The questions for the SAT subject physics test.
Heat is added to a 2.0-kg block of ice. The specific heat of water is 4.2 x 10^3 J/Kg'C and the heat of fusion of ice is 3.3 x 10^5 KJ/Kg.
1. How much heat is required to melt the block of ice?
(A) 1.2 x 10^4 J
(B) 6.5 x 10^4 J
(C) 1.7 x 10^5 J
(D) 6.6 x 10^5 J
(E) 8.4 x 10^5 J
2. Once the ice melts, heat is added until the temperature of the water reaches 30'C. How much heat is required to raise the the temperature from 0'C to 30'C?
(A) 8.4 x 10^4 J
(B) 2.5 x 10^5 J
(C) 3.0 x 10^5 J
(D) 6.0 x 10^5 J
(E) 1.9 x 10^6 J
1. Answer is D.
The amount of energy required to melt the ice is found by Q = mH = (2 kg)(3.3 x 10^5 KJ/Kg) = 6.6 x 10^5 J.
2. Answer is B.
The specific heat required can be found using Q = mc.dt = (2 kg)(4.2 x 10^3 J/Kg'C) (30'C) = 2.5 x 10^5 J.
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