How Is the Mass of Neptune Calculated Using Triton's Orbital Data?

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Homework Help Overview

The discussion revolves around calculating the mass of Neptune using the orbital data of its moon Triton. The context includes information about Triton's characteristics and its relationship with Neptune, as well as the orbital mechanics involved in the calculation.

Discussion Character

  • Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the application of Kepler's laws and the relevant formula for calculating mass based on orbital parameters. There are attempts to clarify the correct use of units and constants, as well as the formula itself.

Discussion Status

Some participants have provided guidance on ensuring the correct units are used and have questioned the formula's accuracy. There is an ongoing exploration of the implications of changing the formula and its impact on the calculated mass.

Contextual Notes

Participants note the importance of using standard units and the potential confusion arising from additional information provided in the problem statement. There is also mention of discrepancies in the calculated mass compared to known values.

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[SOLVED] Finding the mass of neptune

Homework Statement


The planet Neptune has 8 moons, the largest of which is Triton. The Voyager II spacecraft has photographed large frozen swampts on the surface of Triton, indication it once had a much warmer climate. Triton may have been a planet itself, migration away from the sun where it was later captured by the gravitational field of Neptune. Neptune requires 164.83 Earth years to complete one orbit around the sun. The diameter of the planet Neptune is 49,528km. Triton orbits Neptune at a mean distance of 354,800km and has an orbital period of 5.88 Eath Days.
Find the mass of Neptune


Homework Equations




I used the equation:4(pi)(radius of satellite ^3 = (Period of Satellite )^2(Mass Focus)(Gravitational constant) , Using Triton as the Satellite and Neptune as the Focus.
My Professor adds some irrelevant information to make the problem more difficult, but I found that the most important figures were the Diameter of Neptune and Distance of Neptune's surface to Triton ( for the Radius of the Satellite) and the orbit time of Triton.

The Attempt at a Solution



When using the above equation I Divide the diameter of neptune in half to find the radius and add it to the distance of triton to neptune to find the Radius of the orbit path (in km). then i multiply it by 4*pi then divide by period^2(in days) and the gravitational constant (6.67*10^-11) to isolate the variable(mass of neptune), after reworking the problem several times and getting the same answer I always get 2.98*10^26kg which from what I can find is about twice the actual mass, if anyone could help me find out what I'm missing in the problem that would be great
 
Last edited:
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(1) Use standard units for time, distance, and mass: seconds, meters, and kilograms.
(2) Double check your formula; Looks to be off by a factor of pi.
 
I changed the factor of pi in the formula to pi^2 and the answer looks correct, thankyou for you help
 


I don't seem to get the pi^2...
when i tried to put that in my calculator the answer would be 2.34*10^26...
 

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