Final answer:
The power output of a 40% efficient coal power plant that consumes 20 million kg of coal per day, with a heat of combustion of 23.9 MJ/kg, is 1.912×108 MJ/day.
Step-by-step explanation:
The student is asking about the power output of a coal power plant with a given efficiency and coal consumption. To calculate the power output, we first determine the total energy produced by burning the coal, then apply the plant's efficiency to find the useful energy output.
The total energy from burning the coal is the product of the mass of coal burned and its heat of combustion. This is calculated as 20 million kg × 23.9 MJ/kg, which equals 4.78×108 MJ/day. Given the plant's efficiency of 40%, we then calculate the useful energy output by multiplying the total energy by the efficiency:
4.78×108 MJ/day × 0.40 (40%) = 1.912×108 MJ/day.
The power output of the plant is then the energy output per day. Therefore, the power output is 1.912×108 MJ/day.