d
\(M =\frac{ W }{ g }=\frac{200}{10}=20\,kg\)

Acc. due to gravity at a depth \(g^{\prime}= g \left(1-\frac{ d }{ R }\right)\)

\(d \rightarrow\) depth from surface

\(d =\frac{ R }{2}\)

\(g ^{\prime}= g \left(1-\frac{ R / 2}{ R }\right)=\frac{ g }{2}=5 m / s ^2\)

weight \(= m \times g\)

at depth \(R / 2=20 \times 5=100\,N\)