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A pendulum clock is 12 s slow per day at 40°C, but it is 4 s fast per day at 20°C. The temperature at which it keeps accurate time, and the linear expansion coefficient (α) of the pendulum rod material, are respectively:
- 30°C; α = 1.85 × 10^−3/°C
- 55°C; α = 1.85 × 10^−2/°C
- 25°C; α = 1.85 × 10^−5/°C
- 60°C; α = 1.85 × 10^−4/°C
Correct answer: 25°C; α = 1.85 × 10^−5/°C
Solution
The pendulum clock's timekeeping is affected by temperature changes, with the clock being slow at higher temperatures and fast at lower temperatures. The correct option indicates that at 25°C, the effects of thermal expansion balance out, allowing the clock to keep accurate time, and the linear expansion coefficient reflects the material's response to temperature changes.
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