7. A block of mass 5.0 kg slides without friction at a speed of 8.0 m/s on a horizontal table surface until it strikes and sticks to a mass of 3.0 kg attached to a horizontal spring (with spring constant k = 1250.0 N-m), which in turn is attached to a wall. How far is the spring compressed before the mass come to rest? (A) 0.30 m (B) 0.40 m (C) 0.54 m (D) 0.67 m.