Is there any friction in this case?

[LokLe]

Homework Statement

How did you account for the friction? Explain

Relevant Equations

F = ma
Fnet = 0
μ = F/N

In the experiment, a cart on an inclined plane of 30 degrees is hooked with the force metre by a line. The line is tension T. It is also subjected to the force of gravity Fg. This makes the cart in static equilibrium. But since the cart is hooked with a line, it does not slide down. The net force should be Fnet = T - Fg +(does it include friction) = 0. The mass of the cart is 0.571428571 kg. Tension is 2.8N. Is there any friction in this case?

Edit: I forget to include the values.

 

[LokLe]

This is the experiment setup.

 

[phystro]

Since there is a finite amount of tension T, friction should also play a role in the static equilbrium. You would have Fg= T+ Friction. Perhaps you would need to work out everything in terms of mg, for the answer to be complete.

 

[LokLe]

Is it possible to calculate the coefficient of static friction using the information provided?

 

[Lnewqban]

Welcome!
What do you think?
Could balance be achieved without any friction between the cart and the incline?
What happens to that balance if the angle is increased to 90 degrees?

 

[LokLe]

The balance could be achieved even without friction since the line (tension T) is holding the cart?
If the angle is increased to 90 degrees, Fnety = mg = T.
So the answer should be friction does not exist in this case.
Sorry if I am wrong, I am new to physics.

 

[phystro]

Certainly, the balance could be achieved even without friction but this is not the same with saying that there is no friction.

 

[LokLe]

So if F net = Fg = T + Fs
(0.571)(9.8)sin(30) = 2.8 + μ(0.571)(9.8)(cos30)
2.8 = 2.8 + 4.846μ
μ = 0
So does this mean that the friction is 0?

 

[phystro]

It should be, but only based in your calculations (which are correct). In general you could also have friction when in static equilibrium, however in this example there was no friction.

 

[phystro]

It doesn't matter if an object is moving or if it is in equilibrium, friction is always a force that must be accounted for.

 

[LokLe]

So if an object is on horizontal ground and it is not moving, what is the friction acting on the object?

 

[phystro]

If there is also a force acting on this object, the friction will be equal in magnitude with the force. Otherwise (if there is no force) you would have no way to know if there is any friction and if there is friction, you wouldn't be able to know its value.

 

[LokLe]

Thanks for helping me clarify the concepts!