Question 398: Gravitation

Question

A body weighs 72 N on the surface of the earth. What is the gravitational force on it, at a height equal to half the radius of the earth?

Accepted Answer

We know W = mg
At a height h, above the surface of earth, weight is given as,
$$mgh = {{mg} \over {\left[ {{{\left( {1 + {h \over R}} ight)}^2}} ight]}}$$
$$ = {{72} \over {{{\left( {1 + {{R/2} \over R}} ight)}^2}}}$$
$$ = {{72} \over {{{\left( {{3 \over 2}} ight)}^2}}}$$
$$ = {4 \over 9} 	imes 72 = 32N$$

Answer

32 N

Answer

30 N

Answer

24 N

Answer

48 N

Gravitation

A body weighs 72 N on the surface of the earth. What is the gravitational force on it, at a height equal to half the radius of the earth?

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