Finding the mass of two planets

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Homework Help Overview

The discussion revolves around a physics problem involving the calculation of the mass difference between two planets based on the weight of a robot on each planet. The problem specifies the robot's mass and the difference in its weight on the two planets, while both planets share the same radius.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the use of a system of equations and the definition of weight. There are attempts to set up equations based on gravitational force, but some participants express confusion about the next steps after establishing initial equations.

Discussion Status

Some guidance has been offered regarding the definition of weight and its calculation at the surface of the planets. Participants are exploring different interpretations of the problem and the relationships between the weights on the two planets, but there is no explicit consensus on how to proceed further.

Contextual Notes

There is mention of the number of submissions used by the original poster, indicating a constraint on attempts. The problem also involves specific values for weight differences and distances, which may influence the discussion.

prlion16
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Ok well, I have used up 2 out of 3 of my submissions for this question. I have tried to do a system of equations and failed twice. I really don't even know where to start so I was hoping that you guys could help me.
The problem is.
The mass of a robot is 5720 kg. This robot weighs 3720 N more on planet A than it does on planet B. Both planets have the same radius of 1.33x10^7 m. What is the difference MA - MB in the masses of these planets?

Thank you.
 
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Use the definition of weight. Assume that it's evaluated at the surface of the planets.
 
ok... I still don't get what I am supposed to do. Sorry. I get that weight is going to be calculated at the surface of the planets so d=1.33x10^7. I got the equation F=6.67x10^-11(5720m1/((1.33x10^7)^2)). I really just don't get what I am supposed to do after this.
 
You are provided with the difference in weight (of the robot), right?
 
For planet B it is 5720a and Planet A is 5720a+3720. right?
 
WA - WB = Gm(MA-MB)/d2
 

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