The weight of a body on the surface of the earth is 100   N . The gravitational force on it when taken…

The acceleration due to gravity changes as one goes to a height from the surface of the earth. Let the new acceleration due to gravity be $g\text{'}$. The formula for acceleration due to gravity at a height is given by $g\text{'}=\frac{g{R}^2}{{\left(R+h\right)}^2}$

The weight of the body on surface is $W=mg=100 \mathrm{N}$

The weight at the given height is $W=mg\text{'}$.

$$\begin{gathered} \Rightarrow W\text{'}=100\times \frac{R^2}{{\left(R+{\displaystyle \frac{R}{4}}\right)}^2} \\ \Rightarrow W\text{'}=100\times \frac{R^2}{{\displaystyle \frac{25R^2}{16}}}=64 \mathrm{N} \end{gathered}$$