System of Particles and Rotational Motion - Result Question 31
31. When a mass is rotating in a plane about a fixed point, its angular momentum is directed along :
[2012]
(a) a line perpendicular to the plane of rotation
(b) the line making an angle of $45^{\circ}$ to the plane of rotation
(c) the radius
(d) the tangent to the orbit
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Answer:
Correct Answer: 31. (a)
Solution:
- (a) $\because \vec{L}=\vec{r} \times \vec{p}$
By right hand screw, rule, the direction of $\vec{L}$ is $\perp$ to the plane containing $\vec{r}$ and $\vec{p}$.
