The wheel weighs 20 lb and rests on a surface for which µB = 0.2. A cord wrapped around it...

The wheel weighs 20 lb and rests on a surface for which µB = 0.2. A cord wrapped around it is attached to the top of the 30-lb homogeneous block. If the coefficient of static friction at D is µD = 0.3, determine the smallest vertical force that can be applied langentially to the wheel which will cause motion to impend.