# Homework Help: Different way to solve projectile motion components?

1. Oct 11, 2008

### wortman

Different way to solve projectile motion components???

1. The problem statement, all variables and given/known data
solve projectile motion formulas for $$\Theta$$ and $$v_0$$
all measurements are in m, t is seconds
$$y_0=.005$$
$$x_0=0$$
the averages from my trials were:
$$x=8.775 m$$
$$t=1.3 s$$

2. Relevant equations
$$x=x_0+v_0*cos\Theta*t$$
$$y=y_0+v_0*sin\Theta*t+.5a_yt^2$$

3. The attempt at a solution
after plugging in my numbers gives:
for x
$$6.75=v_0*cos\Theta$$
which as far as I can see still has two unknowns, where do I go from here?

I'm pretty confused about the y component because I'm not even sure what y is supposed to be. Don't I need a y(max) number first?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Oct 11, 2008

### Redbelly98

Staff Emeritus
Re: Different way to solve projectile motion components???

You don't need ymax necessarily.

What is y when t=1.3s and x=8.775m?

3. Oct 11, 2008

### wortman

Re: Different way to solve projectile motion components???

Alright, so I got some more insight from my roommate and managed to boil the equations down to:
$$6.75=v_0Cos\Theta$$
and
$$8.28=v_0Sin\Theta$$

am I headed in the right direction by then solving the x component for $$v_0=Cos\Theta$$ and then combining it with the y formula to get something like $$8.28=6.75Tan\Theta$$?

BTW I gave the wrong number for $$y_0$$. It should be .0125 m. if you are actually checking my work

4. Oct 11, 2008

### Redbelly98

Staff Emeritus
Re: Different way to solve projectile motion components???

Looks like you're on the right track, though I'm not sure where $8.28=v_0Sin\theta$ comes from.

5. Oct 11, 2008

### wortman

Re: Different way to solve projectile motion components???

does $$6.37=v_0Sin\theta$$ sound better?

6. Oct 11, 2008

### Redbelly98

Staff Emeritus
Re: Different way to solve projectile motion components???

Since I don't know what y is, I don't know.

Welcome to PF, by the way.