In Figure an object of mass `M = 10 kg` is kept on a rough table as seen from above forces are appling on it as shown . Find the direction of static friction if the object does not move `(Take mu = 0.4)`

Explanation

Here limiting value of friction force
`f_("lim") = mu_(s)N = 0.4 xx 10 = 40 N`
The resultant of external forces acting on the block

If the block in at rest `f = F_("net") = 25 N`
As `f lt f_("lim")`
Here actual force actingon the block in less then `f_("lim")` The friction in this case is of static nature
For the direction of friction is force we draw that free body diagram of find the resiltant force
The direction of static friction is opposite to the direction of the resultant force `FR` its magnitude is equal to `25 N` at again
`tan theta = (15)/(20) = (3)/(4) or theta = 37^(@)` as shown in fig