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

Options

A. 0.25 cm
B. 2 cm
C. 4 cm
D. 2.5 cm

Answer

D

Explanation

`mg = N sin theta`
Centripetal force is provided by `N cos theta`
`N cos theta =(mv^(2))/r`

By (i)/(ii) - `tan theta = (rg)/v^(2)` and `tan theta = r/h`
`therefore h = v^(2)/g = (0.5)^(2)/10 = 0.025 m = 2.5 cm`