Aforce of f stretches a certain spring a distance of x. what is the potential energy of the spring when a mass of m hangs vertically from it?

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

Name three different units of energy used to measure heat and describe what type of situations each is usually used.

If anyone who can me with this hw? i would really appreciate it