# Finding the force up an incline given horizontal force

1. Jun 7, 2012

### OneObstacle

1. The problem statement, all variables and given/known data
I need help with part of a problem. I am having problems understanding just how to find the force up an incline when a horizontal force ("headwind") is given.

2. Relevant equations

3. The attempt at a solution
When drawing a triangle to figure it out I draw the hypotenuse as x (force I need to find) and the side adjacent to angle θ as Fapplied. From this, I get cosθ = Fapp/x, therefore x=Fapp/cosθ. However, my online homework listed it as Fapp*cosθ. Did I draw the triangle wrong?

2. Jun 7, 2012

### tiny-tim

Welcome to PF!

Hi OneObstacle! Welcome to PF!
I don't understand which of x and Fapp is the force to be applied, and which is the wind.

(I also don't understand how you can have a horizontal headwind if you're facing up an incline. )

3. Jun 7, 2012

### OneObstacle

The original problem is a skier heading down an incline (sorry, confusing wording). Fapp is the headwind heading into the slope, and Force x is what I randomly assigned the force of the wind acting on the skier.

4. Jun 8, 2012

### tiny-tim

Hi OneObstacle!

(just got up :zzz:)
ohh! … you mean Fx is the component of the wind force in the x direction (ie up the slope)?

ok, then your book is correct …

don't start drawing triangles, just use this rule:

to find the component of a (complete) force, we always multiply by cos of the angle between

Fx = Fappcosθ