1. The problem statement, all variables and given/known data: I asked a question on this topic before, but I want to make sure I know the material well. So, I looked up another question similar to it (and a little more complex) to check my understanding. Here is the practice problem: A board with mass M, when placed into a coil spring (with spring constant k), compresses the spring in a distance of x. A ball of mass m is dropped from rest onto the board from a height h. The ball sticks into the board. What is the restoring force made by the spring? Bonus: What is the amplitude made by the spring? 2. Relevant equations: Conservation of energy, conservation of momentum, Fspring = -kx. vb, final2 = 2ad 3. The attempt at a solution: I am given spring constant k, board mass M, ball mass m, and height h. I noticed that the ball sticks into the board, so it is an inelastic collision. Conservation of energy cannot be applied, but conservation of momentum can. At the instant the ball touches the board, m(vb, final) = (m + M)(v2b) I can find vb, final by using the kinematic equation, vb, final2 = 2ad, with d = h and a = g since it is moving downwards. vb, final is √(2gh). Then, (v2b) = (m*√(2gh))/(m + M)) After collision, I can now apply the conservation of energy. But before that, I take note of how the board already tips the spring from equilibrium. Mg = kx, x0 is the first compression due to the board alone. (Mg)/k = x0. Now, for the energy. (0.5)(m+M)(v2b)2 = 0.5kx12 + (m+M)gx1 x1 is the compression of the spring due to the ball and the board. Solving the quadratic gives me x1. To find restoring force, Fspring = -k (x0 + x1) For the bonus, amplitude is (0.5)((x0 + x1)) Is this right? Did I make errors along the way? Thanks for all the help in advance!