How does friction act between PA and AB in an equilibrium of forces system?

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Homework Help Overview

The discussion revolves around understanding the forces acting on a system in equilibrium, specifically focusing on the frictional force between two components, PA and AB. Participants are trying to determine the direction of the frictional force as part of identifying all forces in the system.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants express uncertainty about the direction of the frictional force and seek clarification on how it acts between PA and AB. There are attempts to visualize the forces and their directions, with some questioning the placement of the gravitational force.

Discussion Status

The discussion is ongoing, with participants providing insights into the nature of friction and its relationship to the contact surfaces. Some guidance has been offered regarding the assumption of friction's direction, but no consensus has been reached on the specifics.

Contextual Notes

There is a mention of a potential misunderstanding regarding the center of mass and the placement of forces, which may affect the analysis of the system. The original question specifies the need to find the angle between PA and AB, which remains unaddressed.

nickyfernandezzz
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Homework Statement


The original question was to find the value of the angle between PA and AB. I have a certain idea regarding how to find it, but first I have to identify all forces acting on the system and their directions. So, I would be grateful if someone can explain how the frictional force acts between PA
and AB.

MY ATTEMPT.
I got a start by marking the forces acting on the system but I can't figure out the direction of frictional force.
 

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nickyfernandezzz said:

Homework Statement


The original question was to find the value of the angle between PA and AB. I have a certain idea regarding how to find it, but first I have to identify all forces acting on the system and their directions. So, I would be grateful if someone can explain how the frictional force acts between PA
and AB.

MY ATTEMPT.
I got a start by marking the forces acting on the system but I can't figure out the direction of frictional force.
Some verbal statement of the problem would be enlightening.
You have marked mg at point Q, but that does not look like the centre.
I assume you are asking about the direction of the frictional force at A. Generally speaking, you do not need to figure that out in advance. Just assume it is one way along the surface, and if you are wrong it should become obvious (and it might just be a matter of flipping the sign to get the right answer).
 
haruspex said:
Some verbal statement of the problem would be enlightening.
You have marked mg at point Q, but that does not look like the centre.
I assume you are asking about the direction of the frictional force at A. Generally speaking, you do not need to figure that out in advance. Just assume it is one way along the surface, and if you are wrong it should become obvious (and it might just be a matter of flipping the sign to get the right answer).
I'm sorry for not being very clear. Actually, it was stated in the question that Q is the centre of AB.
So, is the friction acting ALONG the surface PA ( either upwards or downwards)?
 

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