System of Particles and Rotational Motion - Result Question 37

39. A particle of mass $m$ moves in the $X Y$ plane with a velocity $v$ along the straight line $A B$. If the angular momentum of the particle with respect to origin $O$ is $L_A$ when it is at $A$ and $L_B$ when it is at $B$, then

[2007] (a) $L_A=L_B$

(b) the relationship between $L_A$ and $L_B$ depends upon the slope of the line $A B$

(c) $L_A<L_B$

(d) $L_A>L_B$

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Answer:

Correct Answer: 39. (a)

Solution:

  1. (a) Angular momentum = Linear momentum $x$ distance of line of action of linear momentum about the origin.

$L_A=p_A \times d, L_B=p_B \times d$

As linear momenta are $p_A$ and $p_B$ equal,