Question

A 4-kW electric heater runs for 2 hours to raise the room temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

Answer 1

Q' = 8 KW.h

Q'=28800 KJ

Step-by-step explanation:

Given that

Heat Q= 4 KW

time ,t = 2 hours

The amount of energy used in KWh given as

Q ' = Q x t

Q' = 4 x 2 KW.h

Q' = 8 KW.h

We know that

1 h = 60 min = 60 x 60 s = 3600 s

We know that W = 1 J/s

The amount of energy used in KJ given as

Q' = 8 x 3600 = 28800 KJ

Therefore

Q' = 8 KW.h

Q'=28800 KJ