Q3 of 28 Page 50

A particle of mass m is moving in yz-plane with a uniform velocity v with its trajectory running parallel to +ve y-axis and intersecting z-axis at z = a (Fig. 7.2). The change in its angular momentum about the origin as it bounces elastically from a wall at y = constant is:


According to the question

Initial velocity


After reflection from the wall


Final velocity


Trajectory equation for point of intersection is



Hence change in angular momentum is





{ As }



Hence option b is correct.

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