Question
A metal block is placed in a room which is at 10∘C. It is heated by an electric heater of power 500 W till its temperature becomes 50∘C. Its initial rate of rise of temperature is 2.5∘C/sec. The heater is switched off and now a heater of 100 W is required to maintain the temperature of the block at 50∘C. (Assume Newton's Law of cooling to be valid). The rate of cooling in of the block at 50∘C after switching off the 100 W heater is −1n∘C/s, find n.