Two Packages Are Connected by a Very Light String That

Short Answer

Two packages are connected by a very light string that goes over an ideal pulley as shown in the figure. Package A has a mass of 3.0 kg and can slide along a rough plane inclined at above the horizontal. The string acts on package A parallel to the surface of the plane. The coefficient of static friction between package A and the plane is 0.40 . What minimum mass should package B have in order to start package A sliding up the ramp?