The relationship between angle and static coefficient

[Solweak]

Homework Statement

Hello, I'm very confused about one of my lab activities. It asks "Design a procedure to find the coefficient for static friction of a mass at different angles." But from what I've read online there should be no relationship as you find the static friction from when it begins to slide and the tangent of that angle. Do I just say there is no relationship?

Relevant Equations

tan(θ) = μs

I know you find the static friction of an incline by raising it until it begins to move and then measure the tangent of that angle, but I'm not sure how I'm supposed to show a relationship or create a procedure based off that.

 

[haruspex]

One possibility would be to introduce another (known) force parallel to the slope. I'll leave you to come up with options for that.

 

[Solweak]

One possibility would be to introduce another (known) force parallel to the slope. I'll leave you to come up with options for that.

If we had a pulley and string would that work? Also sorry I'm a little confused but what does the spring system show us?

 

[haruspex]

If we had a pulley and string would that work? Also sorry I'm a little confused but what does the spring system show us?

By having another force in there you can get the slip/no slip boundary at a different angle. Knowing the applied force, you can still calculate the static friction coefficient. You should find it comes out the same, of course, but the scientific spirit says it is worth checking.

 

[Solweak]

By having another force in there you can get the slip/no slip boundary at a different angle. Knowing the applied force, you can still calculate the static friction coefficient. You should find it comes out the same, of course, but the scientific spirit says it is worth checking.

Oh okay, that makes more sense, also if we didn't apply some force wouldn't the applied force be the downhill force from the normal force? So if we didn't do anything the applied force would just be mgsin(a)

 

[haruspex]

Yes. But your diagram omits friction, and you should not show the whole mg as well as a component of it. Just show mg or both components.

 

[Solweak]

Oh okay thank you so much for your time