How Do You Determine the Direction of Rotation Using the Right-Hand Rule?

Click For Summary

Homework Help Overview

The discussion revolves around determining the direction of rotation using the right-hand rule in the context of moments of force about a point. The original poster is attempting to understand how to identify whether the rotation is clockwise (cw) or counterclockwise (ccw) based on the components of a force.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of the right-hand rule and question the reasoning behind the direction of rotation associated with force components. There is an exploration of how to set up the problem and the significance of the distance being perpendicular to the force.

Discussion Status

Some participants have provided guidance on using the right-hand rule to determine the direction of moments, while others are questioning the assumptions made regarding the signs of the terms in the moment calculation. Multiple interpretations of the problem setup are being explored.

Contextual Notes

There is mention of a photo attachment that may provide additional context, and the original poster expresses uncertainty about the principles behind moments, indicating a potential gap in understanding that is being addressed in the discussion.

BigJon
Messages
24
Reaction score
0

Homework Statement



The moment of force Fa about point O

Homework Equations





The Attempt at a Solution



I know how to setup with breaking the force into x,y component but how to tell if its rotating cw or ccw about the point. I think y is ccw but i can't tell on x. I think i would use right hand rule but need to know how to do it correctly.
 

Attachments

  • physics.jpg
    physics.jpg
    6.6 KB · Views: 547
Physics news on Phys.org
Right hand rule would work here. How did you come to conclusion that Fy
"rotates" ccw? If You know the distance and direction of the force, it's easy to determine the direction of moment.

The distance has to be perpendicular to the force, and your fingers have to be directed in the direction of the force, i.e. the direction of rotation. Your palm shows moment direction.
 
Well to setup the prob it would be like -200cos(60)(9in)+200sin(60)(30in), but why is the first term negative if x pulls straight out? My prof. didnt pull this from the book. Maybe I'm not understanding the principle behind moments etc.
 
BigJon said:
Well to setup the prob it would be like -200cos(60)(9in)+200sin(60)(30in), but why is the first term negative if x pulls straight out? My prof. didnt pull this from the book. Maybe I'm not understanding the principle behind moments etc.

Please check the photo that i attached. If you try to rotate Fx around point P, your thumb would be faced down which is the negative z direction, and therefore that moment is also negative.
 

Attachments

  • rotation.JPG
    rotation.JPG
    21.4 KB · Views: 492

Similar threads

  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 6 ·
Replies
6
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
8
Views
1K
  • · Replies 22 ·
Replies
22
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K