Question

Consider a room that is initially at the outdoor temperature of 20°C. The room contains a 40-W lightbulb, a 110-W TV set, a 300-W refrigerator, and a 1200-W iron. Assuming no heat transfer through the walls, determine the rate of increase of the energy content of the room when all of these electric devices are on.

Answer 1

Answer:

1650 W

Explanation:

given data:

Light bulb= 40W

Refrigerator= 300W

iron=1200W

TV= 110W

First we have to balance energy

(rate of energy net transfer)$E_{in}$-$E_{out}$ = (rate of change in internal ,kinetic, potential) d$E_{system}$/dt⇒d$E_{room}$/dt =$E_{in}$

so there is no energy out in any form in this room

$E_{out}$ will be automatically neglected(zero)

therefore,

$E_{in}$=$E_{light} +E_{Tv} +E_{ref} +E_{iron}$

     =40+110+300+1200

     =1650 W

so the rate of increase in energy is d$E_{room}$/dt=1650 W