Q: A mass m is moving with a constant velocity along a line parallel to the x-axis, away from the origin. Its angular momentum with respect to the origin
(a)Is zero
(b)Remains constant
(c)Goes on increasing
(d)Goes on decreasing
Ans: (b)
Sol: Angular momentum $\large \vec{L} = m(\vec{r}\times \vec{v})$
If θ be the angle between $\vec{r}$ and $\vec{v}$ then ,
$\large L = m v r sin\theta $
$\large L = m v h$ ; Where h = perpendicular distance from X axis
Here , m ,v & h all are constant .