NEET (UG) 2025 — Question 30

Weight on Earth's surface: $W = mg = 48\,\text{N}$. Weight at height $h$ above surface: $W' = mg' = m\,g\left(\frac{R}{R+h}\right)^2$. Given $h = \frac{R}{3}$, so $R+h = R + \frac{R}{3} = \frac{4R}{3}$. Then $\frac{R}{R+h} = \frac{R}{4R/3} = \frac{3}{4}$. Thus $W' = 48 \times \left(\frac{3}{4}\right)^2 = 48 \times \frac{9}{16}$. $W' = \frac{48 \times 9}{16} = 3 \times 9 = 27\,\text{N}$. Therefore, the gravitational force at that height is 27 N.