## Thermodynamics: An Engineering Approach 8th Edition

$12kWh$ $43200kJ$
First we determine the amount of electric energy used in $kWh$: $E=(4kW)*(3h)=12kWh$ Now to determine the amount of electric energy used in $kJ$: $4kW = 4\frac{kJ}{s}$ and $3h*\frac{3600s}{h}=10800s$ Then the energy is: $E=(4\frac{kJ}{s})*(10800s)=43200kJ$