A particle is moving in the xy-plane with a constant velocity along a line parallel to the X-axis away from the origin. The magnitude of its angular momentum about the origin.

Options

A. is zero
B. goes on increasing as x is increased
C. goes on decreasing as x is increased
D. remains constant for all positions of the particle

Answer

D

Explanation

Angular momentum `vecL=vecrxxvecp=vecrxxmvecv`
`=m(vecrxxvecv)`
`therefore|L|=mrv sin theta=mv(r sin theta)=mvd="constant"`
(as, m, v, and d are constant)