A horizontal spring attached to a wall has a force constant of k = 760 N/m. A block of mass m = 2.00 kg is attached to the spring and rests on a frictionless, horizontal surface as in the figure below. www m x= x=0 x= x-x/2 x x (a) The block is pulled to a position x; = 5.20 cm from equilibrium and released. Find the potential energy stored in the spring when the block is 5.20 cm from equilibrium. J (b) Find the speed of the block as it passes through the equilibrium position. m/s (c) What is the speed of the block when it is at a position x/2 = 2.60 cm? m/s