A metal block with heat capacity 400 J/°C is heated by a 20 W heater in a room at 10°C. Its temperature finally becomes constant at 50°C. Assume that the rate of heat loss is proportional to the exces

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A metal block with heat capacity 400 J/°C is heated by a 20 W heater in a room at 10°C. Its temperature finally becomes constant at 50°C. Assume that the rate of heat loss is proportional to the excess of its temperature over that of the room. Then:

TestHub · Accepted Answer

Steady state: 20 = k ( 50 − 10 ) , so k = 0.5 W/°C. At 30°C the loss is 0.5 × 20 = 10 W (A) and at 50°C it is 20 W (B). At 30°C the net power is 20 − 10 = 10 W, so the rate of rise is 400 10 ​ = 0.025 °C/s (D). C is false.

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