Question

In a certain time interval, natural gas with energy content of 19000 J was piped into a house during a winter day. In the same time interval sunshine coming through the windows delivered 2000 J of energy into the house. The temperature of the house didn't change. What was ?Ethermal of the house, and what was |Q|, the magnitude of the energy transfer between the house and the outside air?
?Ethermal = J

|Q| = J

Answer 1

Explanation:

Since, it is mentioned the there occurs no change in the temperature. This also means that there will occur no change in thermal energy of the system.

Hence, $\Delta E$ = 0. And, as $\Delta E$ = 0 then there will be no work involved. This means that total energy added to the house will return to the outside air as heat.

Therefore,

                   Q = -(19000 J + 2000 J)

                       = -21000 J

or,    |Q| = 21000 J

Thus, we can conclude that the magnitude of the energy transfer between the house and the outside air is 21000 J.