General Physics I Question: Moment of Inertia Problem Difficulty

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SUMMARY

The discussion focuses on solving a moment of inertia problem in General Physics I, specifically regarding pulley systems. Key advice includes assigning unknowns for tensions in massless and frictionless strings, and the importance of drawing free body diagrams (FBD) for each moving mass. The discussion emphasizes the necessity of writing force/acceleration and torque/angular acceleration equations, while also noting that the original poster (OP) did not provide sufficient effort or a typed version of the problem statement.

PREREQUISITES
  • Understanding of basic mechanics principles, including force and acceleration.
  • Familiarity with free body diagrams (FBD) and their applications.
  • Knowledge of torque and angular acceleration concepts.
  • Ability to work with pulley systems in physics problems.
NEXT STEPS
  • Study the principles of tension in pulley systems.
  • Learn how to effectively draw and analyze free body diagrams (FBD).
  • Research the relationship between linear and angular motion in mechanics.
  • Explore problem-solving techniques for moment of inertia calculations.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone seeking to enhance their understanding of mechanics, particularly in relation to pulley systems and moment of inertia problems.

i_love_space_and_eng
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Homework Statement
https://imgur.com/a/0CPYhEw
Relevant Equations
Attached.
Hi everyone,
I am honestly pretty confused as to where to start with this. Can anyone give any pointers as to where I could possibly go, for (a) and (b)?
Thanks!
 

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i_love_space_and_eng said:
Problem Statement:
Relevant Equations: Attached.

Hi everyone,
I am honestly pretty confused as to where to start with this. Can anyone give any pointers as to where I could possibly go, for (a) and (b)?
Thanks!

You don't need anything on moments of inertia for part a.

For any pulley question, a good place to start is to assign unknowns for the tensions in the strings. If the strings and pulleys are massless and frictionless (other than between string and pulley) you only need one unknown per string. In this question there is only one string.
If a pulley has mass or axial friction then the tensions can be different either side of the pulley, so assign different unknowns.

Next step is to draw a free body diagram for each mass that can move. If a pulley has mass or axial friction, include a FBD for that.
Write force / acceleration and torque / angular acceleration equations for each mass.

Consider which accelerations are the same or related in a known way by the geometry.
 
I'm closing this thread because the OP has not put in enough effort.

Posting the question as an image is not acceptable, especially in this case where it can easily be typed. Also, external image servers should not be used (especially imgur, which is not permanent and recycles urls), but all images should be uploaded to PF.

We also require an attempt at a solution.
 
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The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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