Question

A man weighs $60kg$ at earth's surface. At what height above the earth's surface his weight becomes $30kg$? (radius of earth $=6400km$).

• A. $1624km$
• B. $2424km$
• C. $2624km$
• D. $2826km$

Answer 1

Answer: (C)

$2624km$

Above the earth's surface, $g_1=\frac{g}{(1+\frac{h}{R}{)}^2}$
But changed weight = half of its weight on the earth.
$\Rightarrow g_1=\frac{g}{2}$
$\therefore h=2624km.$