A block of mass 4.0kg on a horizontal surface is attached to a horizontal spring of negligible mass and unknown spring constant. The other end of the spring is attached to a wall, and there is negligible friction between the block and the horizontal surface. When the spring is unstretched, the block is located at x = 0 m. The block is then pulled to x = 0.2 m and released from rest so that the block-spring system oscillates between x -0.2m and 0.2m. The block-spring system undergoes 5 oscillations in 8 seconds. How could a student determine the change in spring potential energy of the system from to by using the diagram and the known information?