Gravitation Question 1

Question 1 - 24 January - Shift 1

The weight of a body at the surface of earth is 18 $N$. The weight of the body at an altitude of 3200 $km$ above the earth’s surface is (given, radius of earth $R_e=6400 km$ )

(1) $9.8 N$

(2) $4.9 N$

(3) $19.6 N$

(4) $8 N$

Show Answer

Answer: (4)

Solution:

Formula: Effect of Altitude

Acceleration due to gravity at height $h$

$g^{\prime}=\frac{g}{[1+\frac{h}{R}]^{2}}$

So weight at given height

$mg^{\prime}=\frac{mg}{[1+\frac{h}{R}]^{2}}=\frac{18}{[1+\frac{1}{2}]^{2}}=8 N$