Calculating Surface Gravity on Planet X?

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Homework Help Overview

The discussion revolves around calculating the acceleration due to gravity on a hypothetical planet, referred to as planet X, which has specific characteristics in terms of radius and density compared to Earth.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to understand how to incorporate density into the calculation of gravity without directly knowing the mass. Some participants suggest calculating mass from density and volume, while others inquire about the formula for volume based on radius.

Discussion Status

Participants are actively engaging with the problem, exploring the relationship between density, volume, and mass. Guidance has been offered regarding the calculation of volume from radius, although there is no explicit consensus on the complete approach to the problem.

Contextual Notes

The original poster expresses uncertainty about how to proceed with the problem given the information provided, indicating a potential gap in understanding the connections between the variables involved.

mandi182
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Homework Statement



Consider a hypothetical extra*solar world, planet X, that has 2.2 times the radius of the Earth and 2.5 times its density.

What is the acceleration due to gravity on the surface of planet X?


Homework Equations


g=GM/r^2



The Attempt at a Solution


I am not sure what to do with density. I know that mass/volume = density, but how do I solve the equation without mass? I know how to solve the equation when I know mass but if I only know density, how do I solve it?
 
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If you know the radius, you can calculate the volume. If you know the volume and the density, you can calculate the mass...
 
How do I use radius to calculate volume? What is the equation to do that?

Thanks
 
Thanks, I wasn't able to get it right but I appreciate your help!
 

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