Gravity Problem two shells, one inside other on particle

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Homework Help Overview

The discussion revolves around a problem involving gravitational forces exerted by two spherical shells on a particle located at a distance from their centers. The context includes concepts from gravitational theory and shell theorem, specifically in an advanced physics setting.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants explore the additive nature of gravitational forces and question the validity of the original poster's approach to calculating the net force on the particle. There is discussion about the clarity of the problem statement and the assumptions made regarding the gravitational interactions.

Discussion Status

The conversation is ongoing, with participants providing feedback on the original poster's reasoning and calculations. Some express uncertainty about the correctness of the approach due to the lack of a clear problem statement, while others affirm the method used. There is a sense of collaborative exploration as participants seek to clarify the situation and refine the understanding of the problem.

Contextual Notes

Participants note the potential for misunderstanding due to the absence of a complete problem statement and the original poster's reliance on visual aids. There is also mention of the expectations set by the homework platform regarding simplification and presentation of answers.

Jediknight
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Homework Statement



Mazur1e.ch13.p70.jpg
wow if this picture posts like this i don't have to explain much, cool. particle is at x=3.0R, answer in terms of G . m(inner) m(particle) r(inner)

Homework Equations


F(1on 2)=Gm(1)m(2)/[r(1-2)]^2

The Attempt at a Solution


The way we prooved gravity can be treated as coming from the center mass of a sphere was based on shells, so I figured I could just treat it as such an add forces
Gm(particle)[(m(inner)/(2.2R)^2+3.0m(inner)/(3.0R)^2]

whats wrong with my thinking here?

(this might be an advanced question idk its engineering physics 2 with calculus, so its not what my school would call introductory physics, but its not fluid dynamics or anything either
 
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How do you know it's wrong? I would've done the same thing. The force of gravity is additive (that is, the resultant force is the vector sum of the individual forces) so I don't see why it wouldn't work.
 
Without a problem statement it is a bit difficult to find out why the answer is wrong -- if it's wrong.
My telepathic capabilities are very limited. What is the question ?
 
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sorry BvU, thought picture was explanitory but I guess I'm in these sections right now so maybe its more obvious to me. I'm finding the sum of the gorces of gravity exerted by the two shells described on a particle placed at x=3

Mastering Physics said I was wrong, I have heard of them being wrong before. but of course every time in the past I've been so frustrated to think that was the case its always an error on my part

thanks for replies! i just found this forum and it seems awsome
 
Your posted answer is fine as far as it goes, but obviously can be simplified. What final form did you submit as answer?
 
haruspex said:
Your posted answer is fine as far as it goes, but obviously can be simplified. What final form did you submit as answer?
I am about to try to simplify after a few problems that I think will help me learn more, it seems like I'm getting this one. mastering physics doesn't usually care too much unless I can cancell out a variable but maybe this time they do

thanks for confirming I am getting the idea, ill pop back to this thread and let you know if I get it "right" and what I enter when I try.

so far I just entered the same thing I put in the first post (Gm(particle)(m(inner)/(2.2R)^2+3m(inner)/(3R)^2) i didn't even square the cooeficients on the R's or combine anything. All I did was pull out G and m(particle) so I didn't have to type them twice. so your probably right
 

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