If a particle of mass m is moving with constant velocity v parallel to x-axis in x-y plane as shown in fig. Its angular momentum with respect to origin at any time t will be

We know that, Angular momentumL→.=   r→xP→  in terms of component becomesAs motion is in x-y plane (z = 0 and Pz = 0), as L→.=  k^ (xpy - ypx)Here x = vt, y = b, px= mv and py = 0∴L→=  k^ [vt×0-b mv] = - mvb k^