how do you find frictional force

Question

anonymous · Answer

It depends if the surface is flat or on an incline.

For a flat surface Friction force = (mass of object in kilograms) * (gravity) = (mass*9.8)
That value is then multiplied by some constant value that is different for all materials.
So F = (k)*(mass)*(9.8)

If the surface is slanted you have to multiply it by the sin of the slope. If the slope is 10 degrees from flat the force of friction is:
F = (constant "k") * mass * 9.8 * sin(10 degrees)

anonymous · Answer

Fr = μN

where:

Fr is the resistive force of friction
μ is the coefficient of friction for the two surfaces (Greek letter "mu")
N is the normal or perpendicular force pushing the two objects together
μN is μ times N
Frand N are measured in units of force, which are pounds or newtons. μ is a number between 0 (zero) and ∞ (infinity).

anonymous · Answer

If the slope is x degrees from flat, you are working with cos x, not sin x, as the component of force normal to the ramp. x=0 is the max not the min of this force.