State and explain Newton's law of gravitation.

Explanation

Statement : Every body in the universe attracts every other body in the universe with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them ' .
Let `M_(1) and M_(2)` The be the masses of the two bodies separated by a distance 'r' Let `vec(r_(1)) and vec(r_(2))` be the position vectors of the two bodies. The force on body (2 ) due to body (1 )
`vec(F)_(21) = (Gm_(1)m_(2))/(r^(3))vec(r)_(12)`
i.e., `vec(F)_(21)=-vec(F)_(12)`
`:. vec(F)_(21) = (Gm_(1)m_(2))/(r^(3)).vec(r)_(12)`
where `vec(F)_(12)` is force on (1) due to `M_(2)` (towards `M_(2)` ).
`vec(r)_(12)` is distance measured from the bod (1) to (2)
`r=|vec(r_(12))|=|vec(r_(2))-vec(r_(1))|=|(x_(2)-x_(1))hat(i)+(y_(2)-y_(1))hat(j)+(z_(2)-z_(1))hat(k)`
i.e ., `r = sqrt((x_(2)-x_(1))^(2)+(y_(2)-y_(1))^(2)+(z_(2)-z_(1))^(2))`