Question:
The friction coefficient between the board and the floor shown in figure is IA. Find the maximum force that the man can exert on the rope so that the board does not slip on the floor.
Solution:
For man
$\mathrm{N}+\mathrm{T}=\mathrm{Mg}$
For board
$N_{g}=N+m g$ (vertical equilibrium)
$T=f f=\mu N_{g}$ (Horizontal equilibrium)
$T=\mu(N+m g)$
$T=\mu(M g-T+m g)$