Physics help: rotational mechanics satellite

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Homework Help Overview

The problem involves a space station designed as a rotating wheel, where the rotation creates artificial gravity for its crew. The scenario describes how the acceleration experienced by the crew changes when some members move from the rim to the center of the station, affecting the angular speed and acceleration at the rim.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss calculating initial and final moments of inertia, angular momentum, and acceleration. There is an emphasis on checking calculations and ensuring the correct application of formulas related to rotational mechanics.

Discussion Status

Participants are actively engaging in the problem-solving process, with one individual identifying a mistake in their calculations related to the moments of inertia. Guidance has been offered to clarify steps and check for errors in reasoning.

Contextual Notes

The problem assumes a uniform distribution of mass and requires consideration of the effects of changing mass distribution on the rotational dynamics of the station.

GreenLantern674
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Homework Statement


A space station shaped like a giant wheel has a radius of 90 m and a moment of inertia of 4.50 108 kg·m2. A crew of 150 are living on the rim, and the station's rotation causes the crew to experience an acceleration of 1g (Fig. P10.47). When 100 people move to the center of the station for a union meeting, the angular speed changes. What acceleration is experienced by the managers remaining at the rim? Assume that the average mass of each inhabitant is 65.0 kg.



Homework Equations





The Attempt at a Solution


I've tried a couple things, including finding the rotational momentum before and after the people move and setting them equal. I did take into account the different moments of inertia and solved for them with I + MR^2, with M being the mass of the people on the outside of the station. I don't know what I'm doing wrong.
 
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Everything you've described so far sounds correct. Show exactly what you did step by step and maybe we can spot an error.
 
Okay, first I figured out the initial rotational velocity by using a=R(omega)^2, using 90m for R and 9.8 m/s^2 for a.
Then I figured out the total initial moment of inertia by doing I + 150(M)(R)^2
I used those to figure out the angular momentum by doing L=(I)(omega), using the I and omega I solved for above, not the given inertia.
I then set rotational momentum equal to [I<sub>given</sub> + 50(M)(R)^2] x omega and solved for omega. Then I used that omega in a=M(omega)^2 to find total final acceleration.
 
Looks great to me. That's how I'd do it. (Are you dealing with an online system? Sometimes they are picky as to the format of the answer.)

What answers did you get for each step of your solution?
 
Okay, I found my mistake. I just made an error adding the moments of inertia. Thanks for your help.
 

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