# Magnitude of the initial velocity of projectile

1. Sep 18, 2011

### vectorunits

A cannon sends a projectile towards a target a distance 1210 m away. The initial velocity makes an angle 26o with the horizontal. The target is hit. The acceleration of gravity is 9.8 m/s2 .
What is the magnitude of the initial velocity?

y = viy•t +0.5•ay•t2
vix = vi•cos(Theta)
vfy = viy + ay*t
I made a triangle with angle 26o, x=605, then solve for Ymax then got 265.214m. I think the next step is solving for time to get some kind of velocity of X or Y. Is 265m correct, what do I solve for next and how?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 18, 2011

### PeterO

Many texts have a derivation of the range of a projectile in general terms, which express the answer merely in terms of the speed and angle of projection [it only applies for level round]. You can use that to solve directly. The derivation is often presented as part of the proof of desired angle for maximum range.