Gravitation and Gravitational Fields

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Homework Help Overview

The discussion revolves around a problem involving gravitational fields and satellite motion, specifically focusing on a satellite designed to orbit Earth at a specified altitude where the gravitational field strength is 4.5 N/kg. The problem includes calculations for distance above Earth's surface, acceleration, and orbital speed.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the distance, acceleration, and speed of a satellite in orbit, expressing confusion about the results and the formulas used. Some participants question the correctness of the formulas applied for velocity and acceleration, while others suggest verifying the understanding of circular motion and orbital mechanics.

Discussion Status

The discussion is ongoing with participants providing feedback on the original poster's calculations and questioning the application of formulas. There is an acknowledgment of the need to clarify the distinction between acceleration and velocity, and some guidance has been offered regarding the correctness of part a).

Contextual Notes

Participants are navigating through the complexities of gravitational calculations and the assumptions underlying satellite motion, with some uncertainty about the formulas and their applicability in this context.

Mary1910
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Homework Statement



A satellite is designed to orbit Earth at an altitude above its surface that will place it in a gravitational field with a strength of 4.5 N/kg.

a) Calculate the distance above the surface of Earth at which the satellite must orbit

b) Assuming the orbit is circular, calculate the acceleration of the satellite and its direction

c) At what speed must the satellite travel in order to maintain this orbit?

Homework Equations



F=G(m1)(m2)/(r)^2

v= √(G)(m) / (r)

The Attempt at a Solution



a)
G=6.67 x 10^-11 N•m^2/kg^2
m=5.98 x 10^24 kg
F=4.5 N/kg

F=G(m1)(m2)/(r)^2

r^2=G(m1)(m2) / (F)

r^2=(6.67 x 10^-11 N•m^2/kg^2)(5.98 x 10^24 kg) / (4.5 N/kg)
r=^2√8.863688889 x 10^13
r=2.98 x 10^13m

∴The distance above the surface of the Earth that the satellite must orbit is 2.98 x 10^13m or 2.98 x 10^10kmb)

v= √(G)(m) / (r)

v=√(6.67 x 10^-11 N•m^2/kg^2)(5.98 x 10^24 kg) / (2.98 x 10^13m)
v=√(9.98866 x 10^14) / (2.98 x 10^13m)
v=3.66 m/s

I don't think that its possible that this could be correct, after looking up a little bit about satellites I found that satellites have a much greater orbital velocity than this. I also don't understand how I am supposed to calculate the direction of the satellite with the information that has been given.

c) And finally, for c) wouldn't my answer just be the same as part b) ? Since I am only maintaining orbit I don't think I need to be concerned about an escape velocity.
Help with these would be really appreciated. Thank you.
 
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The second part asks you to find acceleration , not velocity .
Mary1910 said:
v= √(G)(m) / (r)
This is incorrect . Check the formula for ' v ' once again .

Hope this helps .
 
Qwertywerty said:
The second part asks you to find acceleration , not velocity .

This is incorrect . Check the formula for ' v ' once again .

Hope this helps .

I can't find any other formulas related to acceleration to solve this type of problem. Would it work if I solve for velocity and then divide velocity by time? Although, with this question I don't know if that would work either. Was part a) correct?
 
Do you know circular motion ?

Part A is fine .
 
Would a formula for planet/celestial orbit work for part c? Such as K=G(m1+m2) / (4π^2)
 

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