I think this problem is much more difficult than what I've learned so far.
B) is the problem I'm having a hard time with. I think it is much more difficult to consider because as the red object begins compressing the spring the blue object will begin to move as well.
It also seems apparent that there must be some kind of relationship of how much force is instantaneously transferred to the blue object as it is compressed by the red object.
I'm really not sure how to do this to be honest. I haven't learned how to make work with springs besides energy equations. I've tried the spring constant (N/m) x the incoming speed (m/s) to determine how many newton's per second are being exerted during the collision, but I haven't figured out where to go from there.