# physics

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when an object is 100m above the surface of earth. The earth's attraction for it is 10N. In order then the earth's attraction on the same object is only 5N. how far should be taken to object be away from surface of earth.

• physics -

F1 =G•m•M/R1²
F2= G•m•M/R2²
F1=10 N, F2 = 5 N
F1=2F2
G•m•M/R1² =2 G•m•M/R2²
1/R1²=2/R2²
R2=√2•R1

Earth’s radius is R = 6.378•10^6 m.
h1=100 m, h2=?

R1=R+h1
R2=R+h2

R+h2=√2• (R+h1),
h2 =[√2• (R+h1)] – R.

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