# Projectile Motion without Initial Velocity

1. Aug 20, 2013

### PerryKid

Projectile Motion without Initial Velocity (Only time and angle given)

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

A projectile is launched at an angle of 50° above the horizontal and it hits the ground in 12 seconds.

a. Calculate the maximum height of the projectile.
b. Find the range of the projectile.

2. Relevant equations

$H_{max}=\frac{V_{o}^{2}+sin^{2}\theta}{g}$

$R=V_{o}\sqrt{\frac{2H}{g}}$

3. The attempt at a solution

I don't know where to start. I can't solve without Vo and I am missing Vo.

Last edited: Aug 20, 2013
2. Aug 20, 2013

### lewando

Can you not use a standard kinematic equation to get vy0?

3. Aug 20, 2013

### PerryKid

I need [STRIKE]Vo to find height and range, not Vyo[/STRIKE]

EDIT: I found a formula to help me solve it all!

$V_{y}=V_{o}Sin(\theta)-gt$

$V_{y}=0$

4. Aug 20, 2013

### lewando

But if you can find vy0, then you can find v0 with some simple trig.

5. Aug 20, 2013

### lewando

That will work. At what t will vy = 0?