Question

An object with a mass of `7 kg` is lying still on a surface and is compressing a horizontal spring by `5/4 m`. If the spring's constant is `3 (kg)/s^2`, what is the minimum value of the surface's coefficient of static friction?

Answer 1

The coefficient of static friction is `=0.055`

Explanation:

The mass is `m=7kg`

The compression of the spring is `x=5/4m`

The spring constant is `k=3kgs^-2`

The reaction of the spring is `R=kx=3*5/4=15/4=3.75N`

The acceleration due to gravity is `g=9.8ms^-2`

The normal reaction of the object is `N=mg=7*9.8=68.6N`

The coefficient of static friction is

`mu_s=R/N=3.75/68.6=0.055`