Please solve this problem The variation of temperature with

The variation of temperature with position in a wall is shown below for a specific time, t_l, during a transient (time-varying) process. Is the wall being heated or cooled? Explain why? (answer is HEATED)

Solution

As we can see the temperature at x=0 (at position of wall) is high during transient process. And we can see temperature is decreasing as the distance from the wall is increasing and also with increase of time. so we can conclude that with time heat is flowing from wall towards positive direction of \'x\' with maximum heat at x=0 which is acting as source of heat. Thus we can say the wall is being heated.