Ablock of mass 0.510 kg is pushed against a horizontal spring of negligible mass until the spring is compressed a distance x. the force constant of the spring is 450 n/m. when it is released, the block travels along a frictionless, horizontal surface to point circled a, the bottom of a vertical circular track of radius r = 1.00 m, and continues to move up the track. the speed of the block at the bottom of the track is va = 13.7 m/s, and the block experiences an average frictional force of 7.00 n while sliding up the track. what is x? and what is the speed of the block if it reaches the top?