Question

a steam engine of efficiency 70% burns 20g of coal to produce 10kJ of energy. if it burns 200g of coal per second, calculate its power output.

Answer 1

As 200g of coal is 10 times more than 20g of coal, then the power output of 200g of coal is 10 times more than 20g of coal and is equal to 100kJ. The information about the engine efficiency is excess.