Relative angular velocity in a rotating rod

Click For Summary

Discussion Overview

The discussion revolves around the concept of relative angular velocity in a rotating rod, specifically focusing on the angular velocity of the end of the rod relative to its midpoint. Participants explore different methods to calculate this relative angular velocity and question the validity of their approaches.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes that the relative angular velocity of the end B with respect to the midpoint of the rod could be calculated as zero, since both points share the same angular velocity w.
  • Another participant suggests that to find the relative angular velocity, one must first calculate the linear velocities of both end B and the midpoint, leading to a different conclusion.
  • A participant questions why two different methods yield different answers, indicating confusion about the calculations involved.
  • Another participant advises establishing a coordinate system to clarify the motion of points on the rod, suggesting that the frame of reference affects the interpretation of rotation.
  • One participant expresses confusion regarding the coordinate system explanation and seeks clarification.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct method for calculating relative angular velocity, and multiple competing views remain regarding the validity of the proposed approaches.

Contextual Notes

Participants express uncertainty about the assumptions underlying their calculations and the implications of different coordinate systems on the analysis of motion.

TyrionTestBok
Messages
3
Reaction score
0
Consider a rod AB rotating about one of it's end A with angular velocity w.
Now angular velocity of each point of the rod is same i.e. w.
But if we have to find the relative angular velocity of the end B w.r.t. mid point of rod, what it will be?

Will it be zero because, w-w=0

or first we have to find the velocity of end B which is wR(R is length of Rod)
then find velocity of mid-point wR/2 and then find relative velocity of end B w.r.t. to mid point which is
wR-wR/2=wR/2
then divide it by distance between B and mid point which is R/2 and get relative angular velocity which now comes out to be w.

Which method is right and why the other method is wrong?
 
Physics news on Phys.org
TyrionTestBok said:
Now angular velocity of each point of the rod is same i.e. w.
You seem to have answered your own question.
 
Svein said:
You seem to have answered your own question.
But why two answer are coming through different method?
 
Make your xy coordinates at the end that is stationary. Clearly, as you say, the other end is rotating in that frame of reference.

Now make your xy coordinates with the x-axis along the rod and the y-axis perpendicular to that. Are any points on the rod rotating in that frame of reference?
 
phinds said:
Make your xy coordinates at the end that is stationary. Clearly, as you say, the other end is rotating in that frame of reference.

Now make your xy coordinates with the x-axis along the rod and the y-axis perpendicular to that. Are any points on the rod rotating in that frame of reference?
I didnt get you. Sorry :(
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
Replies
1
Views
1K