Three block of masses `1kg`, `4 kg` and `2 kg` are placed on a smooth horizontal plane as shown in figure. Find
(a) the acceleration of the system,
(b) the normal force between `1kg` block and `4 kg` block,
( c) the net force on `2kg` block

Explanation

(a) `a = ("Net pushing force")/("Total mass")`
`= (120-50)/(1 + 4 + 2)`
`= 10m//s^(2)`

(b) `120 - R = 1xxa = 10`
`R = 110N`
( c) `F_("net") = (2) (10)
`= 20 N`