Conservation of Angular Momentum Help

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Homework Help Overview

The discussion revolves around a problem related to the conservation of angular momentum, specifically focusing on the energy considerations of a ball in motion. Participants are examining the roles of translational and rotational energy in determining the maximum height of the ball.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the necessity of factoring in both translational and rotational energy when calculating the maximum height. There is a discussion about the implications of treating the ball as a point mass and the lack of specific information regarding its rotation rate.

Discussion Status

Some participants have provided insights into the assumptions made in the problem, particularly regarding the treatment of the ball as a point mass and the implications of not having information on its rotational dynamics. There is an acknowledgment of the complexities involved in real-life scenarios versus the simplifications expected in the problem.

Contextual Notes

Participants note the absence of information regarding the diameters of the balls and the rotation rate, which limits the ability to fully incorporate rotational energy into the analysis. The discussion also highlights the lack of consideration for friction and deformation in the problem setup.

Speedking96
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Homework Statement


Below is the question:

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I only have an issue with the last step of the problem. Why wouldn't you factor in the translational AND rotational energy of the ball and then solve for maximum height?
 
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The translational kinetic energy of the ball is the rotational kinetic energy of a system consisting of the ball alone when using a reference axis such that the ball's radial velocity is zero.
 
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Speedking96 said:
Why wouldn't you factor in the translational AND rotational energy of the ball and then solve for maximum height?

In a real life problem you'd have to do that. In this problem, you have no information that would allow you to calculate a specific number for the rotation rate for the 5 kg ball. You don't know the diameters of the balls. The book expects you to treat them as "point masses".

Without considering friction or the deformation of the objects,, how could the bar impart any rotation to the 5 kg ball?
 
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Alright, I understand. Thank you.
 

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