A conical pendulum consists of a simple pendulum moving in a horizontal circle as shown in the figure. C is the pivot, O is the center of the circle in which the pendulum bob moves and ω is the constant angular velocity of the bob . If L→ is the angular momentum about point C, then

Method-1:The distance of L→ is perpendicular to the line joining the bob at point C. Since this line keeps changing its orientation in space, direction of L→ keeps changing, however, as ω is constant, magnitude of L→ remains constant.Method-2: The torque about point is perpendicular to the angular momentum vector about point C. Hence it can only change the direction of L→ and not its magnitude.