I need help finding k and make a graph. In this lab we put a 511g cart and used a spring to launch it up an incline with weights increasing by 100g. The formula I was told to use is k/2Δx^2=mgh but i can’t figure out how to find the x or k. All the data we recorded is in the pictures “ Determine the energy stored in a dynamic cart Determine the spring constant of the dynamic cart's spring”

22. the top of a cliff is located a distance h above the ground. at a distance h/2 there is a branch that juts out from the side of the cliff, and on this branch a bird's nest is located. two children throw stones at the nest with the same initial speed, one stone straight downward from the top of the cliff and the other stone straight upward from the ground. in the absence of air resistance, which stone hits the nest in the least amount of time?