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

1650 W

Step-by-step 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