Question

The value of $g$ at the surface of earth is $9.8\, m / s ^{2}$. Then the value of ' $g$ ' at a place $480 \,km$ above the surface of the earth will be nearly (radius of the earth is $6400\, km$ )

• A. $9.8\, m / s ^{2}$
• B. $7.2 \,m / s ^{2}$
• C. $8.5\, m / s ^{2}$
• D. $4.2 \,m / s ^{2}$

Answer 1

Answer: (C)

$g_{h}=g\left[\frac{R}{R+h}\right]^{2}$
$\Rightarrow g_{h}=9.8\left[\frac{6400}{6400+480}\right]=8.48 \,m / s ^{2}$