Question

An object with a mass of `4 kg` is lying still on a surface and is compressing a horizontal spring by `7/8 m`. If the spring's constant is `16 (kg)/s^2`, what is the minimum value of the surface's coefficient of static friction?

Answer 1

`0.36`

Explanation:

The spring applies a force of `-kx = -16xx7/8 N = -14 N`

Now the force of friction on the object = `mumg = mu4xx9.8 N`

so, if it is not moving, net force on the body must be zero,

hence:

`mu4xx9.8 = 14`
`=> mu = 7/19.6 ~~0.36`