Question

An object with a mass of `5 kg` is on a ramp at an incline of `pi/12`. If the object is being pushed up the ramp with a force of `8 N`, what is the minimum coefficient of static friction needed for the object to remain put?

Answer 1

The minimum coefficient of static friction needed is `0.07`.

Explanation:

You have to visualize the force's diagram of the object.
Assuming the sistem with `x` on the surface of ramp and `y` on the normal of surface.
There is the orizontal component that is `F(x)=|8N-(mgsin15°)|=4.7N`
If the object remains "put": Friction Force=F(x)
`F(f)=CF(y)=C(mgcos15°)=4.7N`
and `C=4.7/66.33=0.07`.