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Satellites againby six789
Tags: satellites 
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#1
Apr305, 04:58 PM

P: 127

here is another problem...
a 650kg satellite is to be placed into synchronus orbit around Earth. What amount of work must be done onthe satellite to raise it into synchronous orbit? i did.. W=GMm(1/r of Earth  1/r of synchronous satellite) = 6.673x10^11N m^2/kg^2 (5.98x10^6kg)(650kg)(1/6.38x10^6m  1/4.22x10^7m) W = 3.442998737X10^10 J the right answer is 3.7x10^10 J... is ther something wrong with the significant digits?? can anyone tell me the mistake that i did? 


#2
Apr305, 06:03 PM

P: 618

six789,
What kind of energy did you calculate for the satellite? Does it have any other kind when it's in orbit? 


#3
Apr305, 07:59 PM

P: 127

a) the gravitational potential energy is 4.1x10^10 J
b) the total enrgy is 3.1x10^9 J d) the kinetic enrgy is 3.1x10^9 J 


#4
Apr305, 08:01 PM

P: 2,218

Satellites again
The kinetic energy in this case is not the same as the potential energy. The only time kinetic energy = Potential energy is when the change in kinetic energy is caused by a change in potential energy. In this case, the potential energy is always cosntant as in a circular orbit, the satelite is always the same distance from the earth.



#5
Apr305, 08:51 PM

P: 127

i get the right answer from doc al... he said that...
change of energy = WorkEnerg(total) change=work therefore.. Work = WorkE =3.442998737X10^10 J  (3.1x10^9 J) =3.75x10^10J.. so the answer is right!!! thanks again for the help... 


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