Right hand rule for Spinning things

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Discussion Overview

The discussion revolves around the application of the right hand rule in the context of angular momentum, angular velocity, and torque, particularly in relation to rotating solid bodies. Participants explore the implications of viewing direction on the interpretation of clockwise and counterclockwise rotations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how to apply the right hand rule for angular momentum, angular velocity, and torque, particularly when the direction of rotation (clockwise or counterclockwise) depends on the observer's viewpoint.
  • Another participant suggests that as long as the same orientation is used consistently, the right hand rule will yield correct results, explaining that the angular vector points in the direction of the thumb when the palm is oriented in the direction of rotation.
  • A question is raised about the relationship between angular momentum and angular velocity, specifically whether they point in the same direction, and how this relates to the cross product formulation (L = r x p), which is said to yield a vector perpendicular to the plane formed by r and p.
  • Further clarification is provided that angular momentum is treated similarly to angular velocity in terms of direction, reinforcing the use of the right hand rule.
  • A participant reflects on their initial misunderstanding, comparing the relationships among angular momentum, angular velocity, and torque to those in electric and magnetic fields, indicating a need for clearer connections between these concepts.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding regarding the application of the right hand rule and its implications for angular momentum and torque. There is no consensus on the clarity of these concepts, as confusion persists among some participants.

Contextual Notes

Participants highlight the dependence of the right hand rule application on the observer's perspective, which may lead to different interpretations of rotation direction. The discussion also touches on the mathematical relationships involved, such as the cross product, without resolving the underlying complexities.

Forgetful_Duck
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Right hand rule for Spinning things...

Hi, I'm havign a hard time figuring out how the right hand rule works for Angular momentum, Angular velocity and torques.

Its so confusing because At university we get problems about rotating solid bodys like a disk on a rod, and when the question specifies the wheel direction as Clockwise and or anti clockwise, spinning on a horizontal axis.
I am not sure from WHICH point of view is the axis clock or anti clockwise.

When you look at a spinning object, being clock or anti clock depends on which side you look at it from...

Which also comes to my next confusing dilema.

If the direction of clock or anti clock depends on which side the obserevr views then using the right hand rule, doesn't that give 2 completely different sets of answers for angular velocity, anuglar momentum and torque?

Am i confusing anyone yet?

Can someone pelase explain to me how i should apply the right hand rule to find vector direction of velocity, anuglar momentum and torques!

Thanks
 
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As long as you use the same orientation, when doing the problem it won't matter.

Right hand rule means that if an object is rotating counter-clockwise, with the axis pointed at you, then the angular vector will point at you. With right hand rule, orient your palm so that the objects rotation is in the same direction that your fingers go from open to close, with your palm so oriented, the angular vector points in the direction of your thumb.
 
Then what about the Direction of Torque and angular momentum?

Angular momentum is in the same direction as angular velocity?

But how does that work when L = r x p , shouldn't it be perpendicular?
 
Forgetful_Duck said:
Then what about the direction of Torque and angular momentum?
Treated the same as angular velocity, with right hand rule.

But how does that work when L = r x p , shouldn't it be perpendicular?
r and p lie on a plane, and the angular vector is always perpendicular to this plane, via right hand rule.
 
Ah!

Thanks, this makes a lot more sense now.

I was under the impression that the 3 were related by the right hand rule like how Force, Field, and Direciton of current were related via the right hand rule in the topic of Electric and Magnetic Fields. Where you use 3 finegrs of the right hand, thum = current , fore finger field and rude finger force. lol

Thanks for cleaing this up.
 

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