A gas is enclosed in a system, where weights are added to the piston, givinging a total mass of 2.20 Kg. As a result, the gas is compressed and the weights are lowered 0.250 m. At the same time, 1.50 J of heat evolves from the system. What is the change in internal energy of the system, delta U. The force of gravity on a mass m is mg, where g is the constant acceleration of gravity (g=9.80 m/s^2).