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By Newton's law of cooling, a hot tea cup at 90°C in a room at 25°C cools so that:
ACooling rate is proportional to (T − 25)
BCooling rate is proportional to T alone
CCooling rate is proportional to T²
DCooling rate is constant over time
Answer & Solution
Correct answer: A. Cooling rate is proportional to (T − 25)
Newton's law: dT/dt = -k(T − T_env) = -k(T − 25). Rate ∝ DIFFERENCE between T and ambient. Solution: T(t) = 25 + (T_0 - 25) e^(-kt). Asymptotes to 25°C.
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