Calculating Height of a Twice-Daily Orbit Above Earth's Surface

In summary, the conversation revolves around finding the height of a top secret spy satellite orbiting the Earth twice each day, given the circumference of the orbit, mass, and centripetal force are not given. The only known information is the period of 12 hours and the value of gravity, 9.8m/s2. There is a discussion of using the equations Fc = m*v2/r and Fg = Gm1m2/r2 to solve for r, but confusion arises due to not knowing all the variables. However, it is pointed out that assuming the gravitational force is the centripetal force can lead to a solution. After some guidance, the conversation ends with the suggestion to not assume that a number needs
  • #36
Orodruin said:
Apart from the fact that you again have way too many significant digits. You really do not have more than two at best. I suggest writing the answer in units of Mm (megameter) or, even in units of the Earth's radius. Giving nine significant digits you are essentially saying you know all the input variables to a precision that would be the same as knowing your height with a precision of the size of an atom. This is completely unreasonable.
I used meters to try to keep the units the same.
So if my smallest significant figures is 9.8, with 2 significant digits, then the final answer would be 2.6E7 m?
 
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  • #37
somekid99 said:
I used meters to try to keep the units the same.
I suggest you get comfortablr with prefixes. That is what they are for.

You also forgot to remove the Earth radius now.
 
  • #38
Orodruin said:
I suggest you get comfortablr with prefixes. That is what they are for.

You also forgot to remove the Earth radius now.

I have subtracted the radius with Earth's radius in the previous post.

Isn't mega meter the same thing as kilometer? I don't understand the difference? So your'e putting it in kilometers but you write it as mega meters?
 
  • #39
somekid99 said:
Isn't mega meter the same thing as kilometer?
No, mega and kilo are different prefixes. Why would they be the same? While kilo denotes ##10^3##, mega denotes ##10^6##.
 
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