# Choosing directions, vectors

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1. Dec 27, 2015

### Cozma Alex

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

2. Relevant equations

3. The attempt at a solution
When I have to describe a motion i'm supposed to decompose a vector in two directions, for example in an inclined plane is decompose the weight in these directions: the normal to the plane and the parallel to the plane, and that seems logic, but could I decompose the weight in other directions? The same thing for the velocity in a parabolic motion, I decompose the velocity in the vertical and the horizontal directions because it is easier but could I describe the motion using other directions?for example the horizontal and another one inclined with the horizontal by an angle different of 90 ?

I think I could because it's a matter of choice, the motions doesn't change, changes just the way you look at it

2. Dec 27, 2015

### Mister T

You are free to make these choices. Often you can turn a difficult problem into an easy one by a clever choice of coordinate directions.

3. Dec 28, 2015

### SammyS

Staff Emeritus
In regard to your last question:
"... for example the horizontal and another one inclined with the horizontal by an angle different of 90° ?"​

You can decompose a vector into two components which are not mutually perpendicular. However, that tends to cause more problems than it solves..