Topic: Heat Transfer
A beaker filled with hot water in a room cools from 70°C to 65°C in t1 minutes, 65°C to 60°C in t2 minutes and from 60°C to 55°C in t3 minutes. Then,
- A. t1 > t2 > t3
- B. t1 = t2 = t3
- C. t1 < t2 < t3
- D. cannot be concluded
Answer: C. t1 < t2 < t3
Explanation: According to Newton's Law of Cooling, the rate of cooling is directly proportional to the temperature difference between the body and its surroundings. As the temperature of the water gradually decreases, the temperature difference between the water and the room also decreases, leading to a progressively slower cooling rate. Consequently, it takes more time to cool by each subsequent 5°C interval, meaning t1 < t2 < t3.