Two blocks of masses `4kg` and `2kg` are placed side on a smooth horizontal surface as shown in the figure. A horizontal force of `20N` is applied on `4kg `block. Find
(a) the acceleration of each block.
(b) the normal reaction between two blocks.

Explanation

(a) Both the blocks will move with same accleration `(say a)` in horizontal direction.

Let us take both the blocks as a system. Net external force on the system is `20N` in horizontal direction.
Using `sumF_(x) = ma_(x)`
`20=(4+2)a=6a`
or `a = (10)/(3)m//s^(2)`