Circular Motion: Homework on Force, Acceleration, Velocity

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Homework Help Overview

The discussion revolves around a physics problem related to circular motion, specifically focusing on gravitational force, acceleration, and orbital velocity of a satellite in orbit around Mars. The original poster presents calculations based on given parameters, including the mass of Mars and the satellite, as well as the altitude of the satellite's orbit.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the need to convert altitude from kilometers to meters for accurate calculations. There is a question regarding the correct radius to use in the calculations, particularly whether to include the altitude in the total distance from the center of Mars. Additionally, there is a query about the specific type of acceleration being sought.

Discussion Status

Participants are actively engaging with the original poster's calculations, providing guidance on correcting errors and clarifying the problem setup. There is a recognition of the correct equations being used, but also a focus on ensuring the values and assumptions are accurate before proceeding to further parts of the problem.

Contextual Notes

There is an emphasis on the importance of using the correct radius in calculations, as well as the need for clarity on what type of acceleration is being referenced. The original poster has not yet moved on to the final part of the problem due to uncertainty in the previous calculations.

runningirl
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Homework Statement



You'replanning a mission to Mars and wish to put your satellite, which has a mass of 2000 kg, i orbit around Mars at an altitude of 300 km. Mars has a mass of 6.42*10^23 kg and a radius of 3400 km.

a) What's the force of gravity acting on the satellite while it is in orbit?
b) What's the acceleration?
c) The velocity?

Homework Equations



F=GMm/r^2
F=mv^2/r

The Attempt at a Solution



for part a:

since G=6.67*10^-11
F=(6.67*10^-11)(2000)(6.42*10^23)/(3400+200)^2
=6255865595 N?

b) F=ma
6255865595=2000(a)
a=3127932.798 m/s/s?

i wasn't sure if i did parts a and b right so i didn't move onto c yet.
 
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For part a:
Convert km to m for radius values.
The question specifies an altitude of 300km but your calculations uses 200km?

For part b:
What acceleration are you looking for?

For part c:
Orbital Velocity = SquareRoot(GM/r)
where r is the distance from the satellite to the centre of the planet, M is the mass of the planet and G as above.

Jared
 
Last edited:
jarednjames said:
For part a:
Convert km to m for radius values.
The question specifies an altitude of 300km but your calculations uses 200km?

For part b:
What acceleration are you looking for?

For part c:
Orbital Velocity = SquareRoot(GM/r)
where r is the distance from the satellite to the centre of the planet, M is the mass of the planet and G as above.

Jared

sorry! i meant 300. but wouldn't the distance from the satellite to the center of the planet be 3400+300 because there's an altitude (for parts a and c)?
 
Correct (which is why I didn't correct your equation, just the value).
 
you have the correct equations just fix the errors Jared pointed out! now do u need help with c?
 

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