Q. Two doors of the same unknown dimension lay inline and parallel horizontally to one another (Example: As viewed from above in an architectural drawing, the inner and outer doors in the same opening of a structure). Door A is the top door in the drawing, door B is on the bottom. Door A rotates on an axis through its left edge, while door B rotates about an axis through its center. The similar force F is applied vertical to each door at its right edge in the same direction on both doors, and the force remains perpendicular as the door turns. Starting from rest, door A rotates through a certain angle in 3 seconds. How long does it take door B to rotate through the same angle?