I Is angular momentum perpendicular to fixed axis of rotation constant?

AI Thread Summary
Angular momentum perpendicular to a fixed axis of rotation is considered constant when torques acting on the system are ignored, assuming sufficient restraints. However, when a rod is hinged and allowed to rotate, the direction of its angular momentum can change at various points during its motion. The discussion raises the question of whether the torques acting perpendicular to the fixed axis also lie within the plane that is perpendicular to that axis. This highlights the complexity of angular momentum behavior in dynamic systems. Understanding these principles is crucial for analyzing rotational motion accurately.
TahirMaqbool
Messages
16
Reaction score
1
TL;DR Summary
Does the component of angular momentum perpendicular to the fixed axis of rotation change in direction or magnitude?
So my book states torques perpendicular to the fixed axis of rotation tend to tilt the axis , however we assume sufficient restraints exist so these torques are simply ignored.
It follows that angular momentum perpendicular to axis remians constant.
(See image )

My question is that if a rod is hinged at one of its ends and allows to rotate, wouldn't angular momentum perpendicular to axis change in direction at each point?
See image below.
 

Attachments

  • IMG_20231228_205312.jpg
    IMG_20231228_205312.jpg
    43.5 KB · Views: 81
  • IMG_20231228_211214.jpg
    IMG_20231228_211214.jpg
    48.3 KB · Views: 91
Physics news on Phys.org
Are those “torques perpendicular to the fixed axis of rotation” also contained in the plane that is “perpendicular to the fixed axis of rotation”?
 
Hello everyone, Consider the problem in which a car is told to travel at 30 km/h for L kilometers and then at 60 km/h for another L kilometers. Next, you are asked to determine the average speed. My question is: although we know that the average speed in this case is the harmonic mean of the two speeds, is it also possible to state that the average speed over this 2L-kilometer stretch can be obtained as a weighted average of the two speeds? Best regards, DaTario
This has been discussed many times on PF, and will likely come up again, so the video might come handy. Previous threads: https://www.physicsforums.com/threads/is-a-treadmill-incline-just-a-marketing-gimmick.937725/ https://www.physicsforums.com/threads/work-done-running-on-an-inclined-treadmill.927825/ https://www.physicsforums.com/threads/how-do-we-calculate-the-energy-we-used-to-do-something.1052162/
Back
Top