Calculate the thermal efficiency of a heat engine given the heat in the hot source is 420.4kJ/kg and the heat in the cold source is 218kJ/kg.

What is work? how much work is done to move an object 0 meters?

To travel at constant speed, a car engine provides 24kw of useful power. the driving force on the car is 600n. at what speed does it travel?

An insulated thermos contains 148 g of water at 72.7 ˚c. you put in a 11.7 g ice cube at 0.00 ˚c to form a system of ice + original water. the specific heat of liquid water is 4190 j/kg•k; and the heat of fusion of water is 333 kj/kg. what is the net entropy change of the system from then until the system reaches the final (equilibrium) temperature?