Question

A small mass m is attached to a massless string whose other end is fixed at P as shown in the figure. The mass is undergoing circular motion in the x-y plane with centre at O and constant angular speed $\omega .$ If the angular momentum of the system, calculated about O and P are denoted by ${\overrightarrow{L}}_{O}and{\overrightarrow{L}}_P$ respectively, then

• A. ${\overrightarrow{L}}_{O}and{\overrightarrow{L}}_P$ do not vary with time.
• B. ${\overrightarrow{L}}_O$ varies with time while ${\overrightarrow{L}}_P$ remains constant.
• C. ${\overrightarrow{L}}_O$ remains constant while ${\overrightarrow{L}}_P$ varies with time.
• D. ${\overrightarrow{L}}_{O}and{\overrightarrow{L}}_P$ both vary with time.

Answer 1

The correct option is C ${\overrightarrow{L}}_O$ remains constant while ${\overrightarrow{L}}_P$ varies with time.


Magnitude and direction of ${\overrightarrow{L}}_0$ remain constant.
Magnitude of ${\overrightarrow{L}}_p$ remains constant but direction of ${\overrightarrow{L}}_p$ change.