1) A steam engine produces 155 MJ of useful work for every 9 kg of coal. Since coal has a heat of combustion of 31 MJ/kg, what is the minimum temperature of the boiler if the outside temperature is 28oC? Please provide your answer in Kelvin, using K as your unit.
2) Thomas the Tank Engine actually operates in an ideal Carnot cycle. Early in the morning, his fire is not yet completely going: his tank temperature is 190oC, and he only operates at 36 percent efficiency. Later in the day, his tank temperature is up to the normal 540oC. If the outside temperature did not change, what is his percentage efficiency?
3)A Carnot Heat Engine operates between a high temperature TH and a low temperature TL. Which one of the following would increase its efficiency?
a)Increasing TH.
b)Increasing TL
c)Decreasing TH.
d)Making sure that TH and TL are close.