# Electric forces and Electric fields question on x and y components

1. Jul 21, 2011

### mattmro

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

please see the pictures!

2. Relevant equations

F=k(q1)(q2)/r^2

3. The attempt at a solution

okay, I am just curious as to why t cos theta and mg are x components when they are clearly on the y axix!
I thought you used cos for x components and sin for y components

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2. Jul 21, 2011

### mattmro

guys I know im a DA, i barely got by in physics I and I was able to get by without knowing how to do these type of problems, now I cant plz help!

3. Jul 21, 2011

### mikelepore

The cosine of theta is the adjacent side of the triangle divided by the hypotenuse. With theta defined to be where it is in this problem, T cos theta is the vertical component of the tension.

4. Jul 22, 2011

### cupid.callin

Where is it written that they are on X axis .... looks on Y to me
Maybe they took X as Y and Y as X

OP's asking why the vertical component is called X component

5. Jul 22, 2011

### mikelepore

I already read the question and the images about ten times before answering. It sounds to me like a teacher may have pounded it into the student's head that x means horizontal and then always take the cos, y means vertical and then always take the sin. I have heard some teachers say that, although it is wrong. The cure for the confusion is to identify the triangle and remember the "sohcahtoa" definitions of sin and cos.