Question

An object with a mass of `4 kg` is lying on a surface and is compressing a horizontal spring by `8 cm`. If the spring's constant is `2 (kg)/s^2`, what is the minimum value of the surface's coefficient of static friction?

Answer 1

`mu = 2xx.08/(4xx9.81) = .04/9.81 ~~.004`

Explanation:

Take FBD:
1) y-direction `N = mg`
2) x-direction `F_(ms) = muN`
Insert 1) into 2)
`kx = mumg`
`mu = (kx)/(mg)`
`mu = 2xx.08/(4xx9.81) = .04/9.81 ~~.004`