An object with a mass of 15kg is lying on a surface and is compressing a horizontal spring by 10cm. If the spring's constant is 8kgs2, what is the minimum value of the surface's coefficient of static friction?

1 Answer
Feb 17, 2017

The minimum coefficient of static friction is μ=5.4103.

Explanation:

We know that the frictional force due to static friction will be the normal force of the object on the surface times the coefficient of static friction, μ. The normal force, in turn, is simply the block's mass times the force of gravity:

F=μN
F=gmμ

And Hooke's law tells us that the force due to the spring is...

F=kx

These two values will be equal when μ is at the minimum to keep the block stationary, so we can set the equations equal and plug in given values.

kx=gmμ
kx=gmμ
8.1=9.815μ
.8=147μ
0.0054=μ

And using scientific notation to simplify we get:

μ=5.4103