1. A particular heat engine does 10,000 J of work on a gas on the compression stroke, and the gas does 60,000 joules of work on the power stroke. Which of the following PI diagrams indicates the net work done by the heat engine in one cycle? P P 50,000 J 50,000 J 50,000 J 50,000 3 V V V (a) (b) (c) (d) 2. Two long parallel wires 2.5 meters apart are each carrying 0.50 ampere of current, as shown. Find the magnetic field at point P due to the current in the top wire. P 3. The heat of fusion of gold is 64.5 x 103 J/kg. The melting point of gold is 1063C. If 536 grams of gold is melted, what is the change in entropy? 4.