Kindly solve the following sum:

Dear Student,
​​​​​​As the bullet is fired the pistol recoils. From conservation of momentum,
$$\begin{gathered} mu=MV \\ where, \\ m is the mass of the bullet = 20 g = 0.020 kg \\ M is the mass of the pistol = 1 kg \\ u is the velocity of the bullet = 100 m/s \\ V is the recoil velocity of the pistol \\ V=\frac{mu}{M}=\frac{0.020\times 100}{1}=2m/s \\ Initial momentum of the pistol = 0 \\ Final momentum of the bullet = MV=2 kgm/s \\ Rate of change in momentum, p/t =\frac{2}{20\times {10}^{-3}}=\frac{1000}{10}=100 kgm/s^2 \\ Rate of change in momentum is the magnitude of force on the pistol = 100 N \end{gathered}$$
Regards