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A cup of hot water drops from 60°C to 50°C during the first 10 minutes and then from 50°C to 42°C during the following 10 minutes. What is the temperature of the surrounding medium?

1. 25°C
2. 10°C
3. 15°C
4. 20°C

Correct answer: 10°C

Solution

The temperature drop of the water follows Newton's Law of Cooling, which states that the rate of heat loss of a body is proportional to the difference in temperature between the body and its surroundings. The larger temperature drop in the first interval suggests a higher temperature difference, indicating that the surrounding medium is cooler than the water, leading to the conclusion that the surrounding temperature is 10°C.

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