A block of mass 1.0kg on a horizontal surface is attached to a horizontal spring of negligible mass and spring constant 100N/m. 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=0m. The block is then pulled to x=0.5m and released from rest so that the block-spring system oscillates between x=−0.5m and x=0.5m , as shown in the figure. Which of the following descriptions about the system are correct?
Select two answers.
A) The kinetic energy of the block and the spring potential energy of the system at x=0.25 m are both half of the total mechanical energy of the system.

B) The spring potential energy of the system at x=0.25m is nearly 3.13 J.

C) The kinetic energy of the system at x=0.3m is nearly 4.5J .

D)The sum of the spring potential energy of the system and the kinetic energy of the block at x=0.4m is nearly 12.5J .