Question

A microwave oven has a power requirement of 1,251 W. A frozen dinner requires 5.6 min to heat on full power.(a) How much electrical energy (in kWh) is used? answer with:____kWh(b) If the cost of electricity is 11¢ per kWh, how much does it cost to heat the dinner? (Do NOT round your final answer. Fractional cent values are acceptable.) answer with:¢

Answer 1

a) The first step is to convert 1,251W to KW and 5.6 min to hours

Recall,

1000 W = 1 KW

1251 W = 1251/1000 = 0.1251 KW

60 min = 1 hour

5.6 min = 5.6/60 hours

Thus

electrical energy = 0.1251 x 5.6/60

electrical energy = 0.011676 kWh

b) If the cost of electricity is 11¢ per kWh, then

cost to heat the dinner = 11 x 0.011676

cost to heat the dinner = ¢0.128436