The temperature of the cold reservoir of an ideal heat engine is 35°C. Its efficiency is 34 percent. What
is the temperature of its reservoir? How much is the input energy if it does 3,250 J of work?
Efficiency = 1 - Tcold/Thot where Thot and Tcold are absolute temperatures. So:
0.34 = 1 - (273 + 35)/Thot Rearrange to find Thot in Kelvin (then subtract 273 if you want the result in Celsius).
Efficiency = Work out/Energy_in Substitute the given values and rearrange to find Energy_in