EDIT: I just found the homework board, mods: don't bother moving this thread, just delete it. Thanks We had a lab where we launch springs with an unknown k constant to a target 2.01m away and 0.22m high. We also know the angle at which we shot the spring. We need to find the k constant of the spring, so my question is, does the kinetic energy matter? Will the equation be: Eg + Ee = Eg + Ek (The spring had gravitational potential as it was launched a bit higher than the reference position (the table) or Eg + Ee = Eg Thanks.