Hello, I need some help regarding angular physics. I am working on a project and I want to be able to predict (to some degree) the velocity of the payload leaving the trebuchet. (Excuse my ignorance I am just a high school student) Lets say a trebuchet see diagram has a counter weight m1 distance r1 from the pivot point. I'll just assume that the mass and payload are attached to the arm for simplicity's sake. Also assume the arm makes a 30deg angle with the vertical (theta). I fairly certain that I cannot just use the E=mgh formula to equate velocity because I know some rotational physics are involved here. My attempt was to use Ek=1/2(Moment of inertia)(angular velocity) to find the final velocity. But I did not have angular velocity. Which is (change in angle/time) or (angular acceleration x time) I know that the counterweight is accelerating and therefor likely has rotational acceleration as well. I also believe that only the tangential acceleration/force acts on the arm and that the angle between the vertical (gravity) and the arm would constantly change (and also the tangential component) creating a non-constant acceleration. I thought that since we know acceleration due to gravity, we could figure out how much the counterweight had accelerated the payload to find its velocity. (sort of like finding velocity from an acceleration-time graph). (integration I think) Here's some math I tried Ek=1/2(I)(omega) =1/2[(m)(r^2)](omega) =1/2[(m)(r^2)][(alpha)(time)] =1/2[(m)(r^2)][(tangential acceleration x r)(time)] =1/2[(m)(r^2)][((g / cos theta) x r)(time)] (here is where the non-constant acceleration comes in because of the changing theta value) I've sort of hit a wall here. Because I have no idea how to figure that out. I thought about using torque (t=alpha x I) or work too. I hoping someone can help me out or point me in the right direction.