# Homework Help: Projectile Motion / Kinematics Lab (Only 2 Variables Given)

1. Feb 13, 2012

### dimitri194

1. The problem statement, all variables and given/known data
So, our lab entails the students launching a projectile at a certain angle into a cup at a certain distance away. The launcher is 37 cm off of the ground and the cup is 7cm of the ground, so the Dy = 37-7 = 30cm. We will be given the angle in class and will be asked to position the cup at a certain distance. Lets say for example it is 35 degrees.

How could we solve for Dx with only two variables.
Any thoughts?

Thanks.

2. Relevant equations
tanθ = Vy/Vx

3. The attempt at a solution
I was thinking of using Vx = Vy/tanθ and then possibly substituting something in for Vy from another kinematic equation but that would require time and we are only given measuring tape, no timer.

2. Feb 14, 2012

### TaxOnFear

Hint: we are only given measuring tape.

Welcome to PF!

3. Feb 14, 2012

### Redbelly98

Staff Emeritus
Without knowing the initial speed of the projectile, this problem cannot be solved.