A 0.75mol sample of an ideal monatomic gas is confined in a rigid, thermally insulated container fitted with a movable piston. The gas is slowly compressed so that 350J of mechanical work is done on it while, at the same time, 120J of energy leaves the gas and enters the surroundings through the piston surface.
(a) Calculate the numerical value (including sign) of the change in internal energy of the gas during the compression. Show all work with appropriate units.
(b) State whether the final temperature of the gas is higher than, lower than, or equal to its initial temperature. Justify your answer based on your result from part (a).