Launching spring at targets (physics)? I have a question regarding physics. Its about launching a spring at various targets (bucket) at different distances and heights. What is the equation to find the amount of stretch from equilibrium (in the string) i.e. x. We are given the vertical height, horizontal distance, and the constant of the spring (k=40n/m) Any help would be appreciated. Thank you in advance. I don't have trouble doing it when its on a level surface, but when i have to hit a target at various heights like above 1 meter, or below 1 meter, I struggle to find the equation for the correct stretch from equilibrium.