A gas is confined in a 0.43 m - diameter cylinder by a piston, on which rests a weight. The mass of the piston and weight together is 125 kg. The local acceleration of gravity is 9.811 m/s^2, and the atmospheric pressure is 101.04 kPa. What is the force (in N) exerted on the gas by the atmospheric pressure, the piston and the weight (you may assume that there is no friction between the piston and the cylinder)? If the gas in the cylinder is heated, it expands, pushing the piston and weight upward. If the piston and weight are raised 0.68 m, what is the work done by the gas (in kJ)?