What Is the Precession Radius of a Spinning Stick with Given Parameters?

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Homework Help Overview

The problem involves a stick of length 2L and mass M that spins with angular velocity ω around an axis related to its center of mass (COM). The stick is positioned at an angle Θ with respect to the vertical axis, and there is an initial velocity v directed along the y-axis. The goal is to determine the precession radius R of the stick under these conditions.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the torque τ and angular momentum L, with one participant attempting to relate these to gyroscopic motion. Others question the clarity of the problem statement, particularly regarding the axis of rotation and the physical setup of the stick. There is also a suggestion that the stick may be analogous to a spinning top precessing under gravitational influence.

Discussion Status

The discussion is ongoing, with participants seeking clarification on the initial problem statement and exploring the implications of the assumptions made. Some guidance has been offered regarding the need for a clearer depiction of the spin axis and the conditions under which the stick operates.

Contextual Notes

There are indications of potential errors in the problem statement, particularly concerning the treatment of forces acting on the stick, such as the aerodynamic lift coefficient and the neglect of gravity. The density of air is also mentioned, suggesting that fluid dynamics may play a role in the discussion.

Raihan amin
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Homework Statement


A stick of length 2L and of mass M spins with angular velocity ω around the axis perpendicular to the COM of the stick.It is rotating with making an angle Θ,with the axis parallel to Z axis.The COM has an initial velocity v=υ(to the y axis).Find it's precession radius R.

Homework Equations

.
Angular momentom L=IW
Again L=mυR and [/B]
τ=δL/δt

The Attempt at a Solution


I figure out the torque τ and the change of angular momentum .then i find the gyroscopic relationship W=mgr/Iω
Please help me to find the things out.
Thanks.[/B]
 

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Raihan amin said:
A stick of length 2L and of mass M spins with angular velocity ω around the axis perpendicular to the COM of the stick.
Do you really mean to say this? The COM is a point; an axis cannot be perpendicular to it but can only pass through it. It would help if you posted a drawing showing ##\vec \omega## as a straight arrow to clarify the spin axis. Could it be that the spinning stick is to be treated as a spinning top precessing in the Earth's gravitational field? In that case one end must rest on a horizontal plane and the stick must have a non-zero moment of inertia about its axis.
 
kuruman said:
Do you really mean to say this? The COM is a point; an axis cannot be perpendicular to it but can only pass through it. It would help if you posted a drawing showing ##\vec \omega## as a straight arrow to clarify the spin axis. Could it be that the spinning stick is to be treated as a spinning top precessing in the Earth's gravitational field? In that case one end must rest on a horizontal plane and the stick must have a non-zero moment of inertia about its axis.

Sorry.here the question has some mistake itself.The right version is as follows:
The stick is spinning with angular velocity ω .And the aerodynamic lift coefficient is C. Here gravity should be neglected because the perpendicular part of lift force equate the weight of the stick.
 
And density of air is ρ.
 

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