# Homework Help: Help With Some Physics Related Algebra (Projectile Motion) (Shot Put)

1. Oct 4, 2009

### Brereton55

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

My task is to derive an equation (based on projectile motion of a shot put ball) which gives the range (R) when given initial speed (v), angle of release (theta), and height of release (y)

2. Relevant equations
I've decided to use these equations:

$$v_0= \frac{R}{t*cos \theta}$$

$$y = y_0 + v_0sin\theta* t + (1/2) g t^2$$

3. The attempt at a solution

I solve $$v_0= \frac{R}{t*cos \theta}$$ and get $$t=\frac{R}{v_0*cos \theta}$$

then I plug it into $$y = y_0 + v_0sin\theta* t + (1/2) g t^2$$ for t and make y=0 to get max range.

I just can't seem to solve the algebra though :(

2. Oct 4, 2009

### tiny-tim

Welcome to PF!

Hello Brereton55! Welcome to PF!

(have a theta: θ and try using the X2 and X2 tags just above the Reply box )
Yes, that's fine …

the question isn't asking for the maximum range, only for the actual range for fixed values of v y and θ.