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A body cools from 50.0°C to 48°C in 5s. How long will it take to cool from 40.0°C to 39°C? Assume the temperature of surroundings to be 30.0°C and Newton's law of cooling to be valid.
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- 2.5 s
- 10 s
- 20 s
- 5 s
Correct Option: B
Rate of cooling ∝ temperature difference
between system and surrounding.
As the temperature difference is halved, so the rate of cooling will also be halved.
So time taken will be doubled
t = 2 × 5 sec. = 10 sec.
