Question

If a mass is moving with constant velocity along y axis then prove that its angular momentum about origin is zero

Answer 1

A body of mass M is moving with a constant velocity v along y-axis. Let the perpendicular distance between the y-axis and the path of the particle be r. Then the angular momentum of the body about y-axis is given,

L = r × p, where r is the perpendicular distance between the path of the particle and y-axis, and p is the linear momentum of the particle. Since r and p are perpendicular to each other we have ,

| L | = M | v | |r|= M v r

Now since it is moving along y axis ,the perpendicular distance, that is r,is zero as origin lies on y axis

So L=mvr=mv*0=0

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