Gravity Help: Earth to Moon Distance

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Homework Help Overview

The discussion revolves around determining the point at which lunar gravity begins to dominate for a spacecraft traveling from Earth to the Moon, specifically where the gravitational forces from both bodies are equal in magnitude.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of gravitational force equations to find the distance from Earth where the forces balance. There is uncertainty about the setup and the variables involved, particularly regarding the mass of the spacecraft and the calculations needed.

Discussion Status

Some participants have provided guidance on the approach to take, while others express uncertainty about the appropriateness of the method being used. There is no explicit consensus on the correctness of the calculations or the approach taken.

Contextual Notes

Participants mention the distance between Earth and the Moon as a constraint in their calculations, and there is a suggestion that the original poster should focus on guiding others rather than solving the problem directly.

iamanoob
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For a spacecraft going directly from the Earth to the Moon, beyond what point will lunar gravity begin to dominate? That is, where will the lunar gravitational force be equal in magnitude to the Earth's gravitational force?
m from Earth
i know that the Earth is 3.8*10^8m from the moon
 
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F=G.m1.m2/r^2

m1 = spacecraft = ? = 1000 kg?
m2 = Earth
m3 = luna
G = gravitational constant 6.67 × 10−11 N m2 kg−2

F1= G.m1.m2/r1^2
F2= G.m1.m3/r2^2
r1+r2=3,8.10^8m
F1=F2

4 equations with 4 variables F1,F2,r1,r2. r1 is the answer.

Am I right, I'm not sure.
 
Last edited:
You are right, but you are not supposed to do this thing; you should have better made iamanoob to do this, helping him on his way.
 
Right! But he still has to calculate the answer. :)
 

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