I just have a few quick questions. If I'm given an inital and final velocity how can I use that information to find the launch angle of the projectile? Secondly, having to also do with projectiles, what are the factors which determine how long an object is in projectile flight. I'm pretty sure that the initial velocity and perhaps the mass of the object do. I thought planet's acceleration due to gravity might also. Then I wasn't sure about radius of circular object (i.e. cannonball), or height of cliff - i dont think those could. Help would be appreciated!