5. A coal-burning power plant generates electrical power at a rate of 500 megawatts (MW)
(5.00 × 108
J/s). The plant has an overall efficiency of 37.5% (0.375) for the conversion of heat
to electricity.
a. Calculate the electrical energy (in joules) generated in 1 year of operation and the heat
energy used for that purpose.
b. Assuming the power plant burns coal that releases 30 kJ/g, calculate the mass of coal (in
grams and metric tons) that is burned in 1 year of operation. Hint: 1 metric ton = 1 × 103
kg
= 1 × 10
6
g.