A body is cooled in 2 min in a room at temperature of 30°C from 75°C to 65°C. If the same body is cooled from 55°C to 45°C in the same room, find the time taken (in minute).

Answer

4

Explanation

`(theta_(1)-theta_(2))/(t)=alpha((theta_(1)+theta_(2))/(2)-theta_(0))`
In the first case , `(75-65)/(2)=alpha[(75+65)/(2)-30]`... (i)
In second case , `(55-45)/(t)=alpha[(55+45)/(2)-30]`... (ii)