Question

A body of mass $2\text{kg}$ is moving with constant velocity $10\text{m/s}$ on a straight line $3x+4y+5=0$. Calculate its angular momentum with respect to origin.

• A. $5\text{Js}$
• B. $10\text{Js}$
• C. $15\text{Js}$
• D. $20\text{Js}$

Answer 1

The correct option is D $20\text{Js}$

Given
$4y=-3x-5$
$y=\frac{-3}{4}x-\frac{5}{4}$

$x_{\perp }=\frac{5}{4}\sin \left({53}^{\circ }\right)=\frac{5}{4}\left[\frac{4}{5}\right]=1$

Angular momentum is $L=mv{r}_{\perp }=2\times 10\times 1=20\text{Joule sec}$