Universal law of gravitation(variables)

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SUMMARY

The discussion centers on a physics problem involving the universal law of gravitation, specifically how to determine the radius of a new planet that has twice the mass of Earth while maintaining the same gravitational acceleration. The relevant equation is F=G(m1m2/r²), where G is the universal gravitational constant. By equating the gravitational acceleration of both planets, the relationship between their masses and radii can be established, leading to the solution for the radius of the new planet in terms of Earth's radius.

PREREQUISITES
  • Understanding of Newton's law of universal gravitation
  • Familiarity with gravitational acceleration concepts
  • Basic algebraic manipulation skills
  • Knowledge of the universal gravitational constant (G)
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  • Study the derivation of gravitational acceleration from Newton's law of gravitation
  • Explore the implications of mass and radius on gravitational forces
  • Learn about gravitational field strength and its applications
  • Investigate how changes in mass and radius affect planetary orbits
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Students studying physics, educators teaching gravitational concepts, and anyone interested in planetary science and gravitational effects.

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Homework Statement


A planet has twice the mass of earth, but both planets share the same acceleration of gravity. The radius of the new planet in terms of the radius R of Earth is...?


Homework Equations


F=G(m1m2/r2), G being the universal gravitation constant


The Attempt at a Solution


i think you have to manipulate the equation in some way but i can't figure out what to do first.
 
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From N's law, you have:

[tex] G\frac{Mm}{r^2} = ma_g[/tex]

Because Earth and planet have same acceleration of gravity => a_g(E) = a_g(P) => relationship between masses and radii => radius of planet.
 
thanks, i understand now
 

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