The floor causes a couple moment of MA = 40 N • m and MB = 30 N • m on the brushes of th...

The floor causes a couple moment of M_A = 40 N • m and M_B = 30 N • m on the brushes of the polishing machine. Determine the magnitude of the couple forces that must be developed by the operator on the handles so that the resultant couple moment on the polisher is zero. What is the magnitude of these forces if the brush at B suddenly stops so that M_B = 0?