Question

A particle $P$ is moving along a straight line as shown in the figure. During the motion of the particle from $A$ to $B$ the angular momentum of the particle about $O$:

• A. Increases
• B. Decreases
• C. Remains constant
• D. First increases and then decreases

Answer 1

The correct option is C Remains constant

Angular momentum $L=mvr$

where r is the perpendicular distance between velocity and reference point

Here since the line AB is straight, there would only 1 perpendicular distance from reference point i.e OA

So,

Angular momentum at A $=mvr$

Angular momentum at P $=mvr$

Angular momentum at B $=mvr$

Since, perpendicular distance between the line AB and O will always be R

So all the points lying on the line AB will have same angular momentum equals to mvr.