$($a$)$ What is the minimum force of friction required to hold the system of Figure P$4\mathrm{.}58$ in equilibrium? Let $w_1=120N$ and $w_2=65\mathrm{.}0N.$

$N$

$($b$)$ What coefficient of static friction between the $120N$ block and the table ensures equilibrium?

$($c$)$ If the coefficient of kinetic friction between the $120N$ block and the table is $0\mathrm{.}325,$ what hanging weight should replace the $65\mathrm{.}0N$ weight to allow the

system to move at a constant speed once it is set in motion?

N