Explanation:
The net force along the horizontal direction is
[tex]\sum{F_x} = F_{applied} - f[/tex]
where f is the frictional force. We can find the frictional force by looking at the vertical forces acting on the couch:
[tex]\sum{F_y} = N - mg = 0 \Rightarrow N = mg[/tex]
From the definition of frictional force,
[tex]f = \mu{N} = \mu{mg} = (0.65)(42\:\text{kg})(9.8\:\text{m/s}^2)[/tex]
[tex]\:\:\:\:= 267.5\:\text{N}[/tex]
Therefore, the net force on the couch is
[tex]\sum{F_x} = 600\:\text{N} - 267.5\:\text{kN} = 332.5\:\text{N}[/tex]
