What is the coefficient of friction?

[g65hy]

An object on a 30 degree inclined surface with force applied up the ramp,
weight of object = 6.9N,
applied force on object = 3.13N

My answer was -0.05, but I'm not sure if this is right so I want to make sure with someone's help

Thanks

 

[SammyS]

I'm not sure either. Is there a complete question here?

What's the complete statement of the problem?

 

[g65hy]

yes the information is complete, I had to take it from a table with info in it so there's no complete statement, and btw there's no acceleration

 

[SammyS]

So, these are observed data?

There's no way to know the coefficient of friction, without more information.

You can determine the frictional force -- perhaps -- but not the coefficient .

 

[g65hy]

Ive done it for every other question...but I am in grade 11 and our formula for the coefficient of friction is μ=Ff/Fn

If you don't think there's enough info, could you do just the friction? Thanks

 

[SammyS]

That's IF either of the following is true as well as the direction of the applied force is known.

1. The object is moving at a constant speed. (kinetic friction)

2. The object is stationary, but just on the verge of moving. (static friction.)

 

[g65hy]

1. yes
2. yes

Im only in gr 11 physics so it won't be very complicated

 

[g65hy]

The object is on a high friction surface (sand paper) and is just on the verge of moving at a constant velocity

 

[DukeLuke]

Negative coefficients of friction do not conserve energy. If you want more help you should post more work.

edit: forgot to hit "post" and didn't see previous help

 

[g65hy]

I got negative because since this was a lab, we tried to make the slope 30 degrees but probably wasnt
Thats why my teach says we may get a negative answer

 

[g65hy]

So could anyone work out either the coefficient of friction or just friction?