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neoking77
Jan3-06, 02:40 AM
At a distance H above the surface of a plane, the true weight of a remote probe is one percent less than its true weight on the surface. The radius of the planet is R. Find the ratio H/R.

Work:
Let Mp be mass of planet and Ms be the mass of space probe

(true weight) Ft = GMpM/(r+h)^2

(surface weight) Fs = GMpM/r^2

Ft = GMpMs/r^2 - GMpMs/r^2(0.01)

Ft = GMpMs/r^2 - GMpMs/r^2(0.01) = GMpMs/(r+h)^2

i don't know where to go from here

thanks in advance.

Tide
Jan3-06, 03:49 AM
Multiply both sides by r^2 and write

\frac {r^2}{(r+h)^2}

as

\frac {1}{\left(1 + \frac {h}{r}\right)^2}

You should be able to handle the rest.

neoking77
Jan3-06, 09:00 AM
thank you very much for your help