Homework Help: What are the two possibilities for its x component problem?

1. Sep 17, 2007

mathcrzy

You are given a vector in the xy plane that has a magnitude of 85.0 units and a y component of -40.0 units.
(a) What are the two possibilities for its x component?
____
____
(b) Assuming the x component is known to be positive, specify the vector which, if you add it to the original one would give a resultant vector that is 85.0 units long and points entirely in the -x direction.
Magnitude
____
Direction
____°

2. Sep 17, 2007

Lemm

A. Start by using your Magnitude Formula (pythagorean theorem) and look x value (you will get 2 as its a square root).

3. Sep 17, 2007

mathcrzy

93.9 and -93.9?

4. Sep 17, 2007

learningphysics

careful. (x-component)^2 + (y-component)^2 = magnitude^2.

5. Sep 17, 2007

mathcrzy

thanks. i got it 75 and -75. now what is the second part of the question asking? would it be -85?

6. Sep 17, 2007

learningphysics

No. Just use vector algebra. What is the original vector? what is the resultant vector? write them in the form $$x\vec{i} + y\vec{j}$$.