Question

Give a reason why the coefficient of kinetic friction has no units

Answer 1

To solve this question we must know how friction force works.

Friction force happens every time a surface slides across another surface. The intensity of friction force can be calculated as follows:

`f=\mu\cdot F_N`

where:

μ = coefficient of friction (can be static or kinetic)

FN = normal force (force perpendicular to the surface an object is on)

Forces are measured in newtons (N) as well friction forces. We can then figure out the unit for the coefficient as follows:

`unit\text{ }\mu=\frac{unit\text{ of friction force}}{unit\text{ of force}}`

So:

`unit\text{ of }\mu=(newtons)/(newtons)=1`

which means μ has no units.

That proves our problem.