The sides of the 200-lb door fit loosely into grooves in the walls. Cables at A and B rais...

The sides of the 200-lb door fit loosely into grooves in the walls. Cables at A and B raise the door at a constant rate. The coefficient of kinetic friction between the door and the grooves is μk = 0.3. What force must the cable at A exert to continue raising the door at a constant rate if the cable at B breaks?