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Minimum height for a satellite to remain over the same geographical point 
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#1
Feb1205, 09:39 PM

P: 74

a.)calculate at what height above the earth's surface a satellite must be placed if it is to remain over the same gerographical point on the equator of the earth. b.)what is the velocity of such a satellite?
i have no idea how to do the question, but i know it has to do with these equations: Fcent.=Fgrav. m(v^2)/r=GMm/(r^2) because my book doesn't have answers for this question, i don't know the answer for this question. 


#2
Feb1205, 09:53 PM

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That's the equation u need to use,but under an equivalent form.Now find "r" by plugging the correct numerical values...
Daniel. P.S.HINT:relate angular velocity to tangent velocity... 


#3
Feb1205, 10:07 PM

P: 74

dextercioby, can you please show me some work or maybe even tell me the answer. i am stuck becuase i found that there are two variables, "v" and "r", are unknown.



#4
Feb1205, 10:12 PM

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Minimum height for a satellite to remain over the same geographical point
Yes.[itex] v=\omega r [/itex].And now u have only one variable,namely 'r'...
Daniel. 


#5
Feb1205, 10:15 PM

P: 74

sorry for my ignorance, but what is the w(or omega) thing stands for?



#6
Feb1205, 10:17 PM

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Angular velocity of the Earth's rotation motion.U can find it knowing the period of rotation ("length" of a mean day) and the value of [itex] \pi [/itex],which can be approximated to [itex] 3.14 [/itex]
Daniel. 


#7
Feb1205, 10:19 PM

P: 74

i found the answer for part a of my question to be 35870 km, can you please approve it. thanks alot so far.



#8
Feb1205, 10:28 PM

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It seems correct.However,for point b) u'll need another number,or u can use this 35870Km,but indirectly.
Daniel. 


#9
Feb1205, 10:29 PM

P: 74

anyways (i have a feeling that you arn't going to do the question for me), thanks very much dextercioby for your quick response, it helps me a great deal.



#10
Feb1205, 10:29 PM

P: 74

lol....k thanks



#11
Feb1205, 10:33 PM

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Tell me what number you get for velocity...
Daniel. 


#12
Feb1205, 10:38 PM

P: 74

does 3072.6 m/s sounds good?



#13
Feb1205, 10:40 PM

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Pretty much so.
Daniel. 


#14
Feb1205, 10:41 PM

P: 74

k, thanks again.



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