A cylinder is fitted with a frictionless piston in which a gas is contained as shown in the figure,
The atmospheric pressure is 1 bar and the initial volume and pressure of gas in the cylinder are 0.02 m3 and 0.12 MPa respectively. The cross-section area of the piston is 0.06 m2. The 9.5 kJ of heat is now added and the piston moves slowly from its initial position until it reaches the stop. The spring constant of the linear spring is 20 kN/m. The increase in internal energy of the gas will be ________ kJ (round off to the nearest integer).
Enter numerical value using the virtual keypad. Round off where necessary.