A spring (k=80n/m) lies on a frictionless table, one end connected to the wall, the other to a 4kg block. The block is pulled, stretching the spring .5m. and then released.

A) max elastic potential energy of system?
b) total energy?
C) what is the acceleration of the block at the center of its vibration?
D) what is the blocks velocity when the spring is compressed .2m