1. The problem statement, all variables and given/known data I need to find out how far to pull the spring back so it will travel to the target. The launcher and the target is both set on the floor. The spring is the projectile. I will be given the distance on the day of testing. i should take into account air resistance so i will be more accurate. Mass of spring = 0.024kg k = 25N/m launch angle set at 40 degrees length of spring when not stretched is 0.20m height of launcher is 0.54m My trials pulling spring back and recording distance .25m went .52m .3m went 1.67m .34m went 2.2m .4m went 4.78m .43m went 5.37m 2. Relevant equations conservation of energy Es = Ek 1/2mv^2 = 1/2kx^2 projectile motion d = v1xt v1x = v1cosӨ 3. The attempt at a solution 1/2mv^2 = 1/2kx^2 i get stuck on this part. plugging in numbers but i do not have the velocity. What i do next?