Question

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

• A. $\overrightarrow{L}isconstant$
• B. Only direction of $\overrightarrow{L}$ is constant
• C. Only magnitude of $\overrightarrow{L}$ is constant
• D. Both magnitude and direction of $\overrightarrow{L}$​ changes

Answer 1

The correct option is C Only magnitude of $\overrightarrow{L}$ is constant

The direction of $\overrightarrow{L}$ is perpendicular to the line joining the bob to point C. Since this line keeps changing its orientation in space, direction of $\overrightarrow{L}$ keeps changing however as $\omega$ is constant, magnitude of $\overrightarrow{L}$ remains constant.