A very small particle rests on the top of a hemisphere of radius `20 cm`. Calculate the smallest horizontal velocity to be given to it if it is to leave the hemisphere without sliding down its surface, take `g = 9.8 m//s^(2)`.

Explanation

The particle will leave the hemisphere, when normal reaction `R` becomes zero. In that event,
`(m upsilon^(2))/(r ) = mg`
`:. upsilon = sqrt(r g) = sqrt((20)/(100) xx 9.8) = sqrt(1.96) = 1.4 m//s`