# Projectile Motion, With out numbers

1. Sep 17, 2008

### hockeyboy

Projectile Motion, With out numbers :(

1. The problem statement, all variables and given/known data

A body is projected at an angle such that the horizontal range is equal to three times the greatest height. find the angle of projection.

2. Relevant equations
I dont know

3. The attempt at a solution

all i got so far is that vx= v cos(angle) and vy= v sin(angle)

This is a really tricky question for me and i do not know where to start.

2. Sep 17, 2008

### edziura

Re: Projectile Motion, With out numbers :(

You should be able to look in your text for formulas for horizontal range (R) and max height (h). Use thes formulas to write R = 3 h, and then solve for projection angle theta.

If you don't have these formulas, the problem is a bit longer...

3. Sep 17, 2008

### Dick

Re: Projectile Motion, With out numbers :(

Split in into components. x(t)=vx*t, y(t)=vy*t-(1/2)*g*t^2. Find the range by figuring out when y(t)=0. The height is where y(t) is a maximum. Where is that?

4. Sep 17, 2008

### hockeyboy

Re: Projectile Motion, With out numbers :(

ah. i got it. thanks so much. my final answer was 53.13 degrees.