A mass of 0.5 kg is attached to a massless spring with a spring constnt of k = 600 N/m. The system rests on a level, friction-free surface and is initially at rest. A second mass of .2 kg makes an elastic head-on collision with the mass attached to the spring; thereafter, the oscillating system vibrates with an ampitude of .25 m.
1) What was the incident speed of the second mass?
2) what is the maximum value of the potential energy stored in the spring during the subsequent oscillations?