# Simple Vector Problem - Finding the x-component

1. Jun 10, 2009

### Nulligan

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

A velocity vector 45 below the positive x-axis has a y-component of - 29 .
What is the value of its x-component?

2. Relevant equations

Vx = |V|Cos(Theta)
Vy = |v|Sin(Theta)

3. The attempt at a solution

Theta = -45 degrees
y-component: -29 = xSin(-45) .... where x is the magnitude of the vector

x = Sin(-45) / - 29
...x = 0.2438

So |V| = 0.24~

Vx = (0.24)Cos(-45)
...=0.171

Says it's wrong, and I dont know where to go now. Am a bit embarassed asking for help with a simple problem like this :\

2. Jun 10, 2009

### Nulligan

Oops sorry, nevermind, I realised that in Step 2 I should have divided by Sin(-45)

apologies!

3. Jun 10, 2009

### Nulligan

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

Find x- and y-components of the following vectors
v = 7.0 cm/s, negative x-direction

2. Relevant equations

Vx = |V|Cos(Theta)
Vy = |v|Sin(Theta)

3. The attempt at a solution

I'm a bit stuck here. I slotted in 7cm/s for |v| but how do I find the components if I'm not given an angle or graphical representation?

4. Jun 10, 2009

### Dick

It says 'negative x direction'. I think that means it points along the x-axis in the, uh, 'negative' direction. Are you sure you don't want to rethink posting this question?

5. Jun 10, 2009

### Nulligan

I thought of that after I posted it and came up with -1, 0 as the x,y components [using cos180 and sign 180) which was still wrong. it's late so I wasn't thinking clearly :P