A 10kg block slides towards the 3kg moving block to create a totally inelastic head on collision. The 3kg block comes to a stop after the collision.

Question

1. What speed must the 10kg block be moving at prior to the collision for this to occur?

2. Instead of sliding along a frictionless surface, suppose the 3kg block is now dropped from rest. After free falling through a height of 1m, it comes into contact with a vertically aligned massless spring. The block compresses the spring by 10m from its equilibrium position before finally coming to a stop. What is the spring constant k?