Question

An object with a mass of `8 kg` is on a plane with an incline of `- pi/6`. If it takes `9 N` to start pushing the object down the plane and `4 N` to keep pushing it, what are the coefficients of static and kinetic friction?

Answer 1

The static friction coefficient is `0.13` and kinetic friction is `0.05`.

Explanation:

`mu mgcostheta`=maximum force by which the thing is about to move.
`=>mu mgcostheta=9`(as given)
`=>mu=(9×2)/(8×9.8×sqrt3)`
`=>mu=0.13`(static)
Now same as in the case of dynamic friction,
`=>mu=(4×2)/(8×9.8×sqrt3)`
`=>mu=0.05`(dynamic)