What is the relationship between torque and frictional force in this system?

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Homework Help Overview

The discussion revolves around the relationship between torque and frictional force in a system involving multiple objects on an inclined plane. The original poster attempts to analyze the frictional forces acting on different objects and their implications for motion and rotation.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the comparison of frictional forces between different systems (A, B, and C) and question how these forces relate to the net forces acting on the objects. There is an exploration of free body diagrams and the direction of frictional forces necessary for rolling motion.

Discussion Status

Some participants have provided feedback on the original poster's attempts, affirming the correctness of certain answers and prompting further examination of the free body diagrams. There is an ongoing exploration of the conditions under which the frictional forces are equal and the nature of the frictional force acting on object C.

Contextual Notes

Participants note the requirement that object C rolls without slipping, which influences the type of frictional force considered (kinetic vs. static). There is also mention of specific equations related to torque and net force, although the full implications of these equations remain under discussion.

Joe Armas
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Homework Statement


In the picture

Homework Equations


Torque = I * Alpha
10951894_10200266867310554_1551086073_n.jpg

Alpha = a / r
Fnet = m*a

The Attempt at a Solution


I provided my work in the pictures. I figured out that the frictional force in system B is greater than in system A. I am not sure how to compare this with the frictional force from system C. I figured out the sum if the frictional forces of A and B are equal to mg sin theta, but don't know how the two compare.
 
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Answers to (a) and (b) look good to me. According to (b), objects B and C have the same net force. Look at your free body diagrams for objects B and C. If you add the forces in the diagram for B do you get the same net force as the diagram for C?

What should be the direction of the friction force on C to make it rotate in the right direction for rolling down the plane?
 
TSny said:
Answers to (a) and (b) look good to me. According to (b), objects B and C have the same net force. Look at your free body diagrams for objects B and C. If you add the forces in the diagram for B do you get the same net force as the diagram for C?

What should be the direction of the friction force on C to make it rotate in the right direction for rolling down the plane?
So Friction force on C is pointing up the ramp and its magnitude is equal to friction force on B? The frictional force on C is kinetic not static correct?
 
Joe Armas said:
So Friction force on C is pointing up the ramp and its magnitude is equal to friction force on B?

Yes, that's the only way Fnet,B can equal Fnet,C.

The frictional force on C is kinetic not static correct?

To answer this, remember that the statement of the problem says that C rolls without slipping.
 

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