AP Physics 2 Free Response (Unit 2 Thermodynamics)

This is a publicly released AP Physics 2 question dealing with content from Unit 2, thermodynamics. The question covers PV diagrams, the 1st Law of Thermodynamics and the Ideal Gas Law. "A sample of ideal gas in a thermally insulated container with a moveable piston is initially in state A. As shown in the graph of pressure P as a function of volume V, the gas is taken from state A to state B by an adiabatic process. The dashed lines represent isotherms. (a) Let W be the work done on the gas, Q be the energy transferred to the gas by heating, and ΔU be the change in the internal energy of the gas during the process shown. i. Is W greater than, less than, or equal to zero? Briefly explain your answer. ii. Is Q greater than, less than, or equal to zero? Briefly explain your answer. iii. Is ΔU greater than, less than, or equal to zero? Briefly explain your answer. (b) If the temperature of the gas in state A is 200 K, what is the approximate temperature of the gas in state B? (c) Is your numerical result for part (b) consistent with your explanation for part (a)(iii)? Briefly justify your answer."