1. The problem statement, all variables and given/known data A massless spring with sprint constant k is vertically mounted so that bottom end is firmly attached to the ground, and the top end free. A ball with mass m falls vertically down on the top end of the spring, becoming attached, so that the ball oscillates vertically on the spring. What equation describes the acceleration a of the ball when it is at a height y above the original position of the top end of the spring? Let down be negative, and neglect air resistance; g is the magnitude of the acceleration of free fall. 2. Relevant equations F = -kx vf^2 = vi^2 + 2ax Ei = Ef KE = 1/2 mv^2 PE of spring = 1/2 kx^2 3. The attempt at a solution For this problem, I tried to work backwards given the height y. And I used the kinematics formula and plugged in the intial speed at the point when the ball is oscillated back at the equilibrium of the spring and the final speed being at height y. Then I worked with the F= -kx, letting the force equal to the weight mg, and used 1/2 kx^2 = 1/2 mv^2. then I solved for velocity and plugged that in the equation to find the final velocity at y. I think I went somewhere wrong in here because none of the answers matched. Btw, this a number 16, from the 2008 F = ma exam. And if anyone has enough time, can someone please explain to me the best way of studying for this exam? Would it be a good idea to read the entire mechanics part in the book Fundamentals of Physics? Because I feel I don't really grasp all the material and understand everything. thanks.