1. The problem statement, all variables and given/known data In the pictures. 2. Relevant equations KE = 1/2mv^2. PE = 1/2kx^2 Work external = Delta KE + Delta PE W = F* d 3. The attempt at a solution In the pictures. Comments: On Problem 3 ai, I am not sure whether I have identified the correct horizontal forces. The hint gave two, but I believe there could also be a force that the wall exerts on the spring. I am also not sure which way the force points when a spring is stretched and extended. I believe it is in the direction of the equilibrium unextended position. Please let me know if my answers/reasoning is correct. Thank you.