Solving for Max Height and Angular Velocity of a Thin Rod

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Homework Help Overview

The problem involves a thin rod of length L and mass m that is suspended horizontally and experiences an upward impulse at one end upon release. The goal is to determine the maximum height of the center of mass and the angular velocity of the rod about its center of mass.

Discussion Character

  • Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between angular momentum and impulse, with one participant attempting to relate linear and angular quantities. There is a consensus that the impulse's magnitude is crucial for solving the problem, leading to questions about missing information.

Discussion Status

The discussion is ongoing, with participants exploring the implications of the missing impulse data. Some suggest that the problem may be asking for a functional relationship rather than a numerical solution, while others reiterate the need for additional information to proceed.

Contextual Notes

Participants note that the lack of a specified impulse value limits the ability to solve for the maximum height and angular velocity, indicating that the problem may not provide enough data for a complete solution.

albega
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Homework Statement


A thin rod of length L, mass m is suspended horizontally at rest. It is suddenly released and experiences immediately after an impulse vertically upwards at one end.

I need to find the maximum height reached by the centre of mass and the angular velocity of rotation about the centre of mass.

The Attempt at a Solution


I can't see how there is enough information given in the question. I have used the fact that J=0.5Lp here (J is angular momentum) from the relation between angular and linear impulse, and then this means 0.5Lmv=Iω, with I=mL2/12. Then 0.5Lmv=mL2ω/12. This relates v and ω by v=ωL/6. I could then probably work with constant acceleration formulae to get the answer, however both v and ω are unknowns (and I have to find ω in the next part) so I have no idea where to go.

Thanks in advance :)
 
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The initial velocity of CM ,angular velocity of the rod and the maximum height reached all depend upon the magnitude of impulse . So surely some data is missing from the question.
 
Tanya Sharma said:
The initial velocity of CM ,angular velocity of the rod and the maximum height reached all depend upon the magnitude of impulse . So surely some data is missing from the question.

Yes, as I suspected. Thanks for clarifying.
 
Well to me it looks as thought OP isn't supposed to solve for a number, but max height as a function of I.
 
albega said:

Homework Statement


A thin rod of length L, mass m is suspended horizontally at rest.

Length L, mass M, impulse, I...
 
BiGyElLoWhAt said:
Length L, mass M, impulse, I...

Except that no label is given for the impulse in the question as stated in the OP - that's what's missing.
 

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