Friction Force Calculation at an Angle on Flat Surface

[Thegiver431]

how do you find friction force when applied force is at an angle, this is on a flat horizontal surface.

 

[Dale]

Usually you will need to break at least one force into components.

 

[Maged Saeed]

the static frictional force is :

$$u_sF_n$$

[Us] is constant and [F_n] is the wieght of the object the force is applied to plus the vertical component of the force ,, I think :)

Remember that the frictional force is always in opposite direction of the applied force , that means they would have a different signs

 

[CWatters]

F_n is the force normal to the surface (it need not be the "weight" of the object or even "vertical").

In these two examples the normal force is the weight of the object modified by the vertical component of the applied force F.
http://philschatz.com/physics-book/resources/Figure_06_01_07a.jpg

in a) that would be

F_n = mg+FSin(25)

in b) that would be

F_n = mg-FSin(25)

Since friction is proportional to F_n that means b is easier than a)