A ball of mass 300   g is dropped from a height 10   m above a sandy ground. On reaching the…

Net displacement of the ball under the action of gravity is $\left(10+1.5\right) \mathrm{m}$.

According to work energy theorem, work done by all the forces on a sytem is equal to the change in kinetic energy of the system. Therefore,

$$\begin{gathered} W_g+W_R=0 \\ \Rightarrow mg\left(h+d\right)-F_{R}d=0 \\ \Rightarrow 0.3\times 10\times 11.5-F_R\times 1.5=0 \\ \Rightarrow F_R=23 \mathrm{N} \end{gathered}$$