Consider a vertical piston-cylinder assembly with a 50 kg piston attached to a spring and exposed to atmospheric pressure of 100 kPa. The piston has a surface area of 250 cm^2 and the local acceleration of gravity is 9.81 m/s^2. Heat is now transferred to the system causing it to expand until the volume is 50% greater than the initial volume and reaches 0.003m^3, at which the state pressure in the cylinder is 2 bar. During the process, the spring exerts a force that varies linearly from an initial value of 0 N to a final value. Neglect friction between the piston and the cylinder. Find the has pressure pg if the system is in equilibrium before adding the heat.