Basic Orbit Satalite Questions Please help!

  • Thread starter willbland
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  • #1
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Homework Statement



The polar-orbiting environmental satellites (POES) and some military satallites orbit at a much lower level in order to obtain more detailed information. POES complete an earth orbit 14.1 times per day. What are the orbital speed and the altitude of POES?

T = 1.7 h
G = 6.67x10^-11
M earth = 5.98x10 ^24

Homework Equations



The international space station orbits at an altitude of approximately 226km. What is its orbital speed and period?

The Attempt at a Solution



What i tried to do was,

R^3 = (G)(M Earth)
T^2 _____4π^2
 

Answers and Replies

  • #2
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Somebody please help me ! :(
 
  • #3
D H
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T = 1.7 h
G = 6.67x10^-11
M earth = 5.98x10 ^24

You have units for the orbital period, why not for G and the mass of the Earth? Those things have units too, and unless you apply them consistently you will get the wrong answer. You used the values [itex]G=6.67*10^{-11}\mathrm{m}^3/\mathrm{kg}/\mathrm{s}^2[/itex] and [itex]M_{\oplus}=5.98*10^{24} \mathrm{kg}[/itex] in conjunction with time in hours and distance in kilometers.
 
  • #4
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Thank's.

So how do i do the question?
 
  • #5
D H
Staff Emeritus
Science Advisor
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Make sure you use consistent units throughout. That value of G is in m3/kg/s2. If you want to use that particular value, you had better represent lengths in meters, not kilometers, and time in seconds, not hours.
 
  • #6
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Ooo.. Thanks man :)

But how do i use the equasion when they only give that much information, i am lost :( But i do understand your point.
 

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