1. The problem statement, all variables and given/known data I'm looking at trebuchets. Basically, a trebuchet shoots a projectile with an initial velocity of 30ms-1 at an angle of 55, 65 and 75 degrees. Friction/Wind resistance do not account. I need to find the maximum height reached, the time the projectile spends in the air and the range. I am having troubles with the time spent in air, therefore affecting my last calculation. I got a maximum height of 30.811m at 55 degrees. 37.71m at 65 degrees. 42.842m at 75 degrees. 2. Relevant equations As mentioned, I'm having trouble finding the total time spent in air. I know I have he following variables. I know that the time to reach max height x2 is the time of flight. Y = Verticle, X = Horizontal Uy= 30ms-1 Vy = 0ms-1 (Obviously no movement at the exact highest point) a= -9.8ms-2 Sy = 30.811m I tried using the rule V = u+at V=u+at T=(v-u)/a This gives me (0-30)/-9.8 Giving me 3.06 seconds and a total time of 6.122 seconds. 3. The attempt at a solution If I wanted to use that equation to find out the time taken if launched at 65 and 75 degrees, I would get the same answer due to the fact that verticle displacement isnt accounted. I've been going over this again and again and I can't figure out anything.