Free body diagram with circular motion

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Homework Help Overview

The discussion revolves around a problem involving two blocks in a circular rotating room, specifically focusing on the forces acting on the blocks, including friction and acceleration. The context is related to circular motion and the dynamics of objects in a rotating frame.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants express uncertainty about the placement of friction vectors and the direction of acceleration. There are attempts to clarify the relationship between friction, normal force, and centripetal acceleration.

Discussion Status

Some participants have provided insights regarding the direction of friction and the nature of centripetal acceleration. There is an ongoing exploration of the forces involved, but no consensus has been reached on the specifics of the friction vector placement.

Contextual Notes

Participants are grappling with the implications of constant speed in circular motion and the necessary forces that contribute to maintaining that motion. There is a mention of confusion stemming from previous lectures, indicating a need for clarification on these concepts.

crybllrd
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Homework Statement


In a circular rotating room (think Gravitron), there are two blocks stacked against the wall and do not drop. Block A is touching block B, and block B is touching the wall.


Homework Equations





The Attempt at a Solution


I know how to do this problem, but I am not sure about where to draw the friction vectors. My intuition tells me straight up, but it seems like my instructor did something different.
 
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crybllrd said:

Homework Statement


In a circular rotating room (think Gravitron), there are two blocks stacked against the wall and do not drop. Block A is touching block B, and block B is touching the wall.


Homework Equations





The Attempt at a Solution


I know how to do this problem, but I am not sure about where to draw the friction vectors. My intuition tells me straight up, but it seems like my instructor did something different.
the friction force opposes the direction of relative motion or pending relative motion between the 2 objects.
 
What about acceleration?
 
ƒ(x) said:
What about acceleration?
What's the direction of the acceleration? What force or forces provides the acceleration??
 
ƒ(x) said:
What about acceleration?
Constant speed.
OK I guess I was right, I must have gotten it confused with another lecture.
Thanks a lot!
 
crybllrd said:
Constant speed.
OK I guess I was right, I must have gotten it confused with another lecture.
Thanks a lot!
Well, you got the direction of the friction force correctly, but not the question about the acceleration. The acceleration of objects moving in a circle is inward toward the center of the circle (centripetal aceleration). Since there is a centripetal acceleration, there must be a centripetal force acting inward for it to accelerate inward (Newton2). That centripetal force is provided by the normal force between the books or book and wall. If there is no normal force, there can be no friction (Friction force less than or equal to u_s(N))!
 

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