Force acting on a projectile - trying to understand the question.... KABOOM!!! I couldn't help it. I just saw a cannon and I had to TRY and solve it from a reason beyond me. Plus, I saw it had calculus in it which I wanna try and practice. Sadly, I'm failing to understand parts of the question. For starters, here's the question. 1. The problem statement, all variables and given/known data http://img853.imageshack.us/img853/9849/calculusproblem.jpg [Broken] Uploaded with ImageShack.us 3. The attempt at a solution Well, I don't know what they mean by giving me this equation for the "force acting on the projectile". And they want me to the determine the projectile's velocity when t = t'? So I need to determine the velocity of the derivative?