Collision between ball and stick

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Homework Help Overview

The problem involves a collision between a glob of clay and a uniform bar on a frictionless table, focusing on the final speed of the center of mass and the angular speed of the combined system after the impact.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply conservation of momentum to find the final speed of the center of mass but expresses uncertainty regarding the subsequent calculation of angular speed. Some participants suggest using conservation of angular momentum, while others question the initial conditions and the definition of angular momentum for the system.

Discussion Status

The discussion is ongoing, with participants providing guidance on using conservation principles. There is exploration of the implications of the center of mass and angular momentum, but no consensus has been reached on the methods or calculations to be used.

Contextual Notes

Participants are considering the changes in the center of mass due to the collision and the implications for angular momentum, but specific details about the initial conditions and assumptions are still under discussion.

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Homework Statement


On a frictionless table, a 0.58 kg glob of clay strikes a uniform 1.62 kg bar perpendicularly at a point 0.18 m from the center of the bar and sticks to it. If the bar is 0.70 m long and the clay is moving at 6.20 m/s before striking the bar, what is the final speed of the center of mass?
A=1.63m/s

At what angular speed does the bar/clay system rotate about its center of mass after the impact?
A=?

[PLAIN]http://img217.imageshack.us/img217/616/prob21a.gif


Homework Equations



Not sure

The Attempt at a Solution



I solved for the final speed of the center of mass using conservation of momentum, but i am lost on the 2nd part. I know the center of mass changes when the clay is attached to the bar, but I am not sure how i would use that to solve the question.
 
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Hi juggalomike! :wink:

Use conservation of angular momentum …

what do you get? :smile:
 
tiny-tim said:
Hi juggalomike! :wink:

Use conservation of angular momentum …

what do you get? :smile:

If i using conservation of angular momentum, which is Ii*Wi=If*Wf the initial side will be 0 because initialy it has no angular velocity?
 
Hello juggalomike,

Think about what is the center of mass of the system (the system being the combination of bar and glob) immediately before impact. Using that point as the center of mass, what is angular momentum (before impact) associated with the bar? And the glob? :wink:
 

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