1. The problem statement, all variables and given/known data I have a physics lab that I'm just not making any progress on. For this lab my group used a 314 g cart. Two springs were used, both attached to the cart, and one being stretched the other compressed. The cart was then ran horizontally and it's velocity was found. I want to find the the spring constant for each trial and then average it. I have the velocities for each trial of the cart after stretching/compressing. The three velocities of the cart after being attached to the stretched or compressed string in m/s are 1.18, 2.68, and 3.65. For the compression trials the velocity in m/s was found to be .2, .7, and 1.0. Natural length of the stretched spring is 6 cm and the compressed 8.4 cm. 2. Relevant equations 3. The attempt at a solution I tried to used the formula given: k= (1/2mv2)/x with x being the distance stretched/compressed. The values I got were kind of funky. I'm thinking I need to use kinetic or potential energy here.