# Homework Help: Trouble with Projectile Motion

1. Sep 29, 2010

### Neek 007

I'm having trouble with projectile motion, mainly with understanding which formulas do what. I understand some, others I do not.
Here are my formulas:

Vx= V cos theta-- I know this is to find x components
Vx= V sin theta-- I know this is to find y components

tan theta=Ry/Rx-- I know i use my resultant x and y components in these, but I don't know what tan theta is.

X=V0t-- I do not understand this formula

Its mainly the V0x and V0y that I do not understand.

2. Sep 29, 2010

### fss

It's the tangent of the angle theta, which is most likely your incident angle.

It has units of (m/s)*(s) = m. Therefore it is a distance. In the above example it'd be the distance in the x-direction.

I think you might mean V0x and V0y? That's more or less standard notation for the initial velocity in the x or y directions.

3. Sep 29, 2010

### iRaid

V0x and V0y are the initial vector components, I was confused on this too.

4. Sep 29, 2010

### Neek 007

Thank you,it's always the small things that can mess one up.

5. Sep 29, 2010

### fizzynoob

this is for 1D motion and you travel at a constant velocity, so keep that in mind