Newton's law of gravitation states that the force of attraction (gravitation) between tow bodies in the universe is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.

Solution:

Given, distance between the moon and the earth (d) = 3 x 10^{5} Km = 3 x 10^{8} m

Mass of the moon (M) = 7 x 10^{22} kg

Mass of the water (m) = 1 kg ( question says every kilogram of water )

Pulling force of the moon (F) = ?

We know,

\(F_i=\frac{GMm}{d^2}=\)

= \(\frac{6.67\times10^{-11}\times7\times10^{22}\times1}{{(3\times10^8)}^2}\)

= \(5.18\times10^5N\)

Every kilogram of water of river is attracted by \(5.18\times10^5N\) of force of the Moon.