1. The problem statement, all variables and given/known data 1) Draw a picture of the situation at three different times: one where the cart is traveling down the track, one where the cart is at maximum extension, and one where the cart is traveling back up the track. Label all relevant quantities on the diagram for each time. 2) Define the system of interest so that you can use gravitational potential energy, spring potential energy, and kinetic energy. Write the energy conservation equation for the system that relates its initial energy to its energy at any point during its motion. 2. Relevant equations For a spring: F=-kx W=mas=F*s k=1/2mv2 μ=-mg(h-h0) E = E0+Wa 3. The attempt at a solution This is for my prelab homework. For the first question, I drew out the three situations. For situation one, the relevant forces are the normal force and gravitational forces. For situation two, when the cart reaches a maximum acceleration, the normal and gravitational forces still apply along with the force of the spring, kx in the opposite direction. For the situation three when the cart moves backwards, the acceleration is in the opposite direction, and the forces of the spring, normal force, and gravitational forces all apply. Question two is where I am stuck. In selecting a situation where an equation can be set up to represent each force, I am thinking that situation three would apply? I'm just having some confusion in setting it up. Here's what I am thinking: K+μ=K0+E0+Wa Fx: 1/2mv2-mg(h-h0)=1/2m0v2-mg(h-h0)-kx+N cos θ Fy: W=mays=0; N sinθ-mg(h-h0)=0 My thanks and appreciation goes out to anyone that looks and checks this for me, I've been having a hard time with it.