Question

A particle of mass M moves along the line y=x with velocity v. Its angular momentum about origin is

Answer 1

From given condition it is clear that particle is moving along $y=x$ axis i.e on straight line as shown in figure.

As we know angular momentum is vector product of distance and linear momentum,

$\overrightarrow{L}=\overrightarrow{r}\times \overrightarrow{p}$

$\overrightarrow{L}=\overrightarrow{r}\times \overrightarrow{mv}$

Here at origin,

$\overrightarrow{r}=0$

so angular momentum will also be zero.