Projectile Motion, With out numbers

[hockeyboy]

Projectile Motion, With out numbers :(

Homework Statement

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.

Homework Equations

I don't know

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.

 

[edziura]

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...

 

[Dick]

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?

 

[hockeyboy]

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