It takes 500 J of work to compress a spring 10 cm. What is the force constant of the spring? (b) When a 3.0 kg block is pushed against a massless spring of force constant 4.5. 10' N/m, the spring is compressed 8.0 cm. The block is released and it slides 2.0 m from the point at which it is released across a horizontal surface before friction stops it. What is the coefficient of kinetic friction between the block and the surface?