A particle describes a horizontal circle i

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A particle describes a horizontal circle in a conical funnel whose inner surface is smooth with speed of $0.5 \,m/s$. What is the height of the plane of circle from vertex of the funnel ........ $cm$

A

$0.25$

B

$2 $

C

$4$

D

$2.5 $

A particle describes a horizontal circle in a conical funnel whose inner surface is smooth with speed of $0.5 \,m/s$. What is the height of the plane of circle from vertex of the funnel ........ $cm$

The particle is moving in circular path

From the figure, $mg = R\sin \theta $ …$(i)$

$\;\frac{{m{v^2}}}{r} = R\cos \theta $ …$(ii)$

From equation $(i)$ and $(ii)$ we get

$\tan \theta = \frac{{rg}}{{{v^2}}}$  but $\tan \theta = \frac{r}{h}$

$h = \frac{{{v^2}}}{g} = \frac{{{{(0.5)}^2}}}{{10}} = 0.025m = 2.5\,cm$