An ideal horizontal spring with spring constant 800 n/m is initially compressed 0.20 m. one end is attached to a wall and the other end touches a 4.0 kg block (not attached). the system is released from rest and the block slides 2.0 m from the release point before coming to rest. the horizontal surface below has a uniform roughness. what can we conclude about the coefficient of kinetic friction between the surface and the block?