# Homework Help: Questions About VECTORS.

1. Sep 29, 2008

### kaylanp01

The problem statement, all variables and given/known data
A) Vector A = 7.00 m and points 40.0o north of east. Vector B = 1.90 m and points 15.0o west of north, and Vector C = 2.10 m and points 15.0o west of south.
What is the magnitude of the resultant vector A+B+C?

B) What angle does the resultant vector A+B+C make with respect to the east?

The attempt at a solution

I know, you wish I hadn't tried. ahaha.

Link incase the above doesn't show up:
http://i36.tinypic.com/f9qcee.jpg

Annnd I also got 5.35 m & 83.2 deg at some point.

Thanks,
KP.

2. Sep 29, 2008

### LowlyPion

Welcome to PF.

Nice picture.

Apparently you understand that the sum of the Vectors can be represented as the sum of the components in x and y.

Unfortunately the y component of your B vector is calculated incorrectly (how can a vector of 1.9 have a 3.37 component?), dooming your effort to get the right answer.

3. Sep 29, 2008

### kaylanp01

woww. silly mistake. forgot to sq rt it. haha. pretend it says 1.84 :). where do i go from there?
Would this be correct?
Sum of y = Ay+By+Cy
Sum of x = Ax+Bx+Cx
?
And then use sin/cos/tan to get the angle?

4. Sep 29, 2008

### LowlyPion

OK. Let's pretend too that you know that the resulting vector is the scalar addition of the x components and the scalar addition of the y components.

Add up all the x's.
Add up all the y's.

Express that as a vector with magnitude - doing that Pythagoras thing you do and figure the angle from the arctan in degrees and then get credit for a right answer.

5. Sep 29, 2008

### kaylanp01

I got it! Thank you thank you! :) Guess I just needed a second set of eyes.

6. Sep 29, 2008

### LowlyPion

Cheers and good luck then.

No more math errors now.

7. Sep 29, 2008

### kaylanp01

Haha no promises, but I will double check my calculations in the future (even the really simple ones). :)

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