A block of mass M on a horizontal surface is attached to a horizontal spring of negligible mass and spring constant 20 N/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 block is pulled to a position beyond the spring’s natural length and released from rest, the block experiences simple harmonic motion. A graph of the force exerted on the spring as a function of the block’s position is shown.
What is the spring potential energy stored in the spring-block system at position B?
a) 0.1J
b) 0.4J
c) 0.9J
d) 1.6J
