a spring has a normal length equal to 15 inches. and the constant for it is 4 pounds per inc. one end of the spring is attached to a stationary support, and the other end of the spring is attached to a movable block which can only travel along a straight horizontal path. after the block has been moved so that the length of the spring was reduced 10 inches. the force that was applied to the block to cause this movement was taken away and the spring was permitted to return to its original length.the amount of work done by the spring in the begining the block back to its original starting position was