Question

A particle having mass $2kg$ is moving along straight line $3x+4y=5$ with speed $8m/s$. Find angular momentum of the particle about origin. $x$ and $y$ are in meters.

Answer 1

$L=mvr$ where $r=$perpendicular distance of velocity from origin.

Since velocity is along line $3x+4y-5=0$

Hence,distance from origin$(0,0)$ is $r=\frac{|3\times 0+4\times 0-5|}{\sqrt{3^2+4^2}}=1$

Hence,$L=2\times 8\times 1$

$⟹L=16kgm/s$