$A$ block of mass $m$ moves on a horizontal rough surface with initial velocity $v$. The height of the centre of mass of the block is $h$ from the surface. Consider a point $A$ on the surface.

  • A

    angular momentum about $A$ is mvh initially

  • B

    the velocity of the block decreases at time passes.

  • C

    angular mometum is not conserved about $A.$

  • D

    All of the above

Similar Questions

$A$ paritcle falls freely near the surface of the earth. Consider $a$ fixed point $O$ (not vertically below the particle) on the ground.

The potential energy of a particle of mass $m$ at a distance $r$ from a fixed point $O$ is given by $\mathrm{V}(\mathrm{r})=\mathrm{kr}^2 / 2$, where $\mathrm{k}$ is a positive constant of appropriate dimensions. This particle is moving in a circular orbit of radius $\mathrm{R}$ about the point $\mathrm{O}$. If $\mathrm{v}$ is the speed of the particle and $\mathrm{L}$ is the magnitude of its angular momentum about $\mathrm{O}$, which of the following statements is (are) true?

$(A)$ $v=\sqrt{\frac{k}{2 m}} R$

$(B)$ $v=\sqrt{\frac{k}{m}} R$

$(C)$ $\mathrm{L}=\sqrt{\mathrm{mk}} \mathrm{R}^2$

$(D)$ $\mathrm{L}=\sqrt{\frac{\mathrm{mk}}{2}} \mathrm{R}^2$

  • [IIT 2018]

Two particles, each of mass $m$ and speed $v$, travel in opposite directions along parallel lines separated by a distance $d$. Show that the angular momentum vector of the two particle system is the same whatever be the point about which the angular momentum is taken.

Consider a particle of mass $m$ having linear momentum $\vec p$ at position $\vec r$ relative to the origin $O$ . Let $\vec L$ be the angular momentum of the particle with respect the origin. Which of the following equations correctly relate $(s)\, \vec r,\,\vec p$ and $\vec L$ ?

Why the angular momentum perpendicular to the axis ${L_ \bot }$ in a rotational motion about a fixed axis ?