Explanation: \(\text{Hints: } g' = g \left(1 - \frac{h}{R}\right)\) \(\text{Solve: } g' = g\left(1 - \frac{1}{2}\right) \implies g' = \frac{1}{2} \cdot g\) \(\therefore g' = 4.9 \, \text{m/s}^2\) \(\text{Ans. (B)}\) \(\text{ব্যাখ্যা: ভূপৃষ্ঠে } g = \frac{GM}{R^2} \dots (i)\) \(\text{ভূপৃষ্ঠ হতে } h \, \text{উচ্চতায়, } g_h = \frac{GM}{(R+h)^2} \dots (ii)\) \(\text{যেখানে, } h \ll R \, \text{থাকলে, } g_h = g\left(1 - \frac{2h}{R}\right).\)