A block of mass 4 kg is attached to a horizontal spring of force constant 120 N/m and to a spring of negligible mass. The string runs over a massless, frictionless pulley to a hanging block off mass 4 kg. Initially the entire system is at rest and the spring is unstretched.
If the 4 kg mass slides on a horizontal frictionless surface, what is the speed of the mass 4 kg when it has fallen a distance 0.1 m downward from its rest poisiton?