In the figure shown,
(a) find the force of friction acting on the block.
(b) state whether the block will move or not. If yes then with what acceleration?

Explanation

Resolving the force in vertical (perpendicular to the plan) direction (except friction)
Here `R` is the normal reation,
`sum F_(Y) =0 rArr R=16N`
`mu_(s)R =0.4xx16=64N`
`mu_(k)R =0.3xx16=48N`
`sum F_(x) = "net driving force" F =(12-4)N =8N`
(a) Since, `Flemu_(s)R` therefore kinetic friction or `4.8N`will act in opposite difection of `F`.
(b)Since, `Flemu_(s)R` the block will move in the direction of `F` (or downwards) with an acceleration,
`a =(F_("net"))/(m) = (F-f)/(m) = (8-4.8)/(2) =1.6m//s^(2)`
this acceleration is in the direction of `F` (or downwards).