# Solving My First Vector Problem: Answers & Explanation

• torrobinson
That sounds about right. In summary, this student is struggling with homework because they are using x's and y's to mean different things on each diagram, and they are also missing something obvious.f

#### torrobinson

I JUST started adding vectors.. as in.. last class. I got a ton of questions, and have done three of them. The answers are given, but I got them wrong. I'll follow the little template already given:

## Homework Statement

What is the net force on a stack of books which are applied two forces: 2.0 N 61 degrees N of W and 59 degrees N of E?

The answer is 75.0 N, 73 degrees (N of E)

??

## The Attempt at a Solution

http://img245.imageshack.us/img245/5965/vectorsao5.jpg [Broken]

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Have you heard of the parallelogram rule yet?

Have you heard of the parallelogram rule yet?

Who in the what? :S

I've never heard of that...

My teacher just did one example on the board, we copied it down as fast as we could, and now I'm trying to do what I think she did...which is what I attempted.

LOL I'm assuming I'm missing something obvious that I've never heard of before.

Thanks

edit: BTW, I'm in Grade 11 and have barley learned anything above the basics.

Maybe that is for the resultant.

Anyways, you can just put them head to tail(like I think you did)...and then solve them similar to how your find the hypotenuse on a right triangle.

Maybe that is for the resultant.

Anyways, you can just put them head to tail(like I think you did)...and then solve them similar to how your find the hypotenuse on a right triangle.

Thanks for the response, but I'm not quite sure what you mean... can you see what I did wrong?

Well, firstly, you're using x's and y's to mean different things on each diagram! Pick a coordinate system (the most conventional is that x components are horizontal, and y components are vertical) and stick to it!

Now, the horizontal components are in opposite directions, so the resultant will be V2x-V1x.

You seem to be close, so try again, this time sticking to a convention, and see how you do.

Well, firstly, you're using x's and y's to mean different things on each diagram! Pick a coordinate system (the most conventional is that x components are horizontal, and y components are vertical) and stick to it!

:O

Holy moly... I haven't made that idiotic mistake since grade 8! And the first time I post a question like this on a forum, It's my lucky day and I do it for the first time in 3 years!

Yes, thanks for pointing that out. I was able to get it.

There's another 2 questions that have nothing to do with mixing up the x/y axis (lol), so they are still problems (I was hoping there was a solution to why all 3 were incorrect)

Thanks

Before posting any more problems, I'll go back and retry the other two to check for more embarrassing mistakes...

This is comparable to last semester when I was frustrated with a single problem involving intersections of circles and lines in Math... only to have somebody point out that I had "1 x 1 = 2". LOL

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