Q

A hot body obeys Newton's law of cooling. Which temperature-versus-time graph represents its cooling? (Graph options are described in words.)

RRB JE 14/12/2014 2014
✓ Answer: D Temperature decreases rapidly at first and then gradually levels off; a concave-up curve
For constant surroundings, T - Ts = (T0 - Ts)e^(-kt). The cooling rate decreases as the temperature approaches the surroundings, giving the curve described in D.