Engineering Board Exam Reviewer · Applications: Cooling, Heating, and Mixture Problems · hard

A body at 100°C is placed in a room held at 25°C. Using Newton's Law of Cooling dT/dt=k(T-25), if the temperature is 80°C after 10 minutes, find k.

1. -0.0310/min
2. -0.0620/min
3. -0.0155/min
4. -0.0450/min

Answer

A. -0.0310/min

Solution

80-25=(100-25)e10k e10k=55/75=0.7333 k= 0.7333/10 -0.0310 per min.

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