The cylinders of a car's engine are 85 mm in diameter. The pistons travel a length of 105 mm during each stroke. The average pressure of the fuel-air mixture in the cylinder during the compression stroke is 8.5 x 105 Pa. (a) What is the work done on the fuel-air mixture during the compression stroke of one piston? (The volume of a cylinder is rh.) (b) The internal energy of the fuel-air mixture before the compression is 1440 J. What is the internal energy after compression?