The weight of a body on the earth is 400   N . Then weight of the body when taken to a depth half of…

The acceleration due to gravity changes with depth from the surface, which is given by

$g\text{'}=g\left(1-\frac{\mathrm{d}}{\mathrm{R}}\right) ...\left(\mathrm{i}\right)$

The given data is 

$$\begin{gathered} W=400 \mathrm{N} \\ \mathrm{d}=\frac{\mathrm{R}}{2} \end{gathered}$$

Multiplying equation (i) with the mass we get the weight.

$$\begin{gathered} mg\text{'}=mg\left(1-\frac{{\displaystyle \frac{R}{2}}}{R}\right)=mg\left(\frac{1}{2}\right) \\ \Rightarrow W\text{'}=\frac{400 \mathrm{N}}{2}=200 \mathrm{N} \end{gathered}$$