A 2-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the amount of electric energy used in both kWh and kJ.

Power (p) = 2kW

Time (t) = 3 h

Work done (w) = ?

p = w / t

w = p * t

w = 2kW * 3 h

w = 6kWh

Converting 6kWh to Joules,

6kWh

6 * (10^3) h (k = 10^3)

6*10^3 * (60*60) (1 hour = 60 * 60 sec)

2.2*10^7 J in 2 significant figures