A body cools in 7 minutes from 60°C to 40°C. The temperature of the surroundings is 10°C. The temperature of the body after the next 7 minutes is:
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Question

A body cools in 7 minutes from 60°C to 40°C. The temperature of the surroundings is 10°C. The temperature of the body after the next 7 minutes is:

G1 Physics · Accepted Answer

Using Newton's law of cooling over equal time intervals, the excess temperature above surroundings decreases by the same factor. Surrounding temperature = 10°C. First 7 minutes: Initial excess = 60 - 10 = 50°C Final excess = 40 - 10 = 30°C Decay factor: 30/50 = 0.6 After the next 7 minutes: new excess = 0.6 × 30 = 18°C Therefore, T = 18 + 10 = 28°C Hence option D follows.