NEET UGPhysicsModerateNEET 2025

A body weighs 48 N on the surface of the earth. The gravitational force experienced by the body due to the earth at a height equal to one-third the radius of the earth from its surface is :

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Sol.

W = mg

and

g = \frac{GM}{R^2}

g_h = \frac{GM}{(R+h)^2}

\Rightarrow \frac{W_h}{W} = \frac{mg_h}{mg} = \frac{g_h}{g} = \frac{R^2}{(R+h)^2} \left(h = \frac{R}{3}\right)

\Rightarrow \frac{W_h}{W} = \frac{R^2}{\left(R + \frac{R}{3}\right)^2} = \frac{R^2}{\left(\frac{4R}{3}\right)^2} = \frac{9}{16}

\Rightarrow W_h = \frac{9}{16}W = \frac{9}{16} \times 48

[

W = 48

= 27 N

Source: geekyrakshit/indian-exam-questions / neet2025-code45

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