A metal cylinder of mass 0.5 kg is heated electrically by a 12 W heater in a room at 15°C. The cylinder temperature rises to 25°C in 5 min and finally becomes constant at 45°C. Assuming that the rate of heat loss is proportional to the excess temperature over the surroundings
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Question

A metal cylinder of mass 0.5 kg is heated electrically by a 12 W heater in a room at 15°C. The cylinder temperature rises to 25°C in 5 min and finally becomes constant at 45°C. Assuming that the rate of heat loss is proportional to the excess temperature over the surroundings

Select all that apply

G1 Physics · Accepted Answer

At the final steady temperature 45°C, heater power equals heat loss. With room temperature 15°C, the loss constant is k=12/(45-15)=0.4 W °C⁻¹. At 20°C, heat loss is k(20-15)=2 W, so A is correct. During heating, m c dT/dt=12-k(T-15). Integrating from 15°C to 25°C over 300 s gives mc=(240/ln(3/2)) J °C⁻¹. Since m=0.5 kg, the specific heat expression printed in option C is the source result. Thus A and C are correct.