Question

The approximate height from the surface of the earth at which the weight of the body becomes $\frac{1}{3}$ of its weight on the surface of earth is [Radius of earth R = 6400 km and √3=1.732]

• A. 3840 km
• B. 4685 km
• C. 2133 km
• D. 4267 km

Answer 1

Answer: (B)

4685 km

Answer 2

According to the given information
$\frac{GM}{(R+h)^2}$=$\frac{1}{3}$×$\frac{GM}{R^2}$
⇒ R+h=√3 R
⇒ h=(√3-1)R∼4685 km
The correct option is (B) : 4685 km