A rigid rod is placed against the wall as shown in figure. When its velocity of lower end is `10 ms^(-1)` and its base makes un angle `a = 60^(@)` with horizontal, then the vertical velocity of its end B will be

Options

A. `10 sqrt3`
B. `10//sqrt3`
C. `5sqrt3`
D. `5//sqrt3`

Explanation

`x ^(2) + y ^(2) = l ^(2) = `constant

`2x (dx)/(dt) + 2y (dy)/(dt) = 0 implies (dx)/(dt) =- V _(A) =- 10`
`(dy)/(dt) = V _(s) & (y)/(x) = tan alpha = tan 60^(@) = sqrt3`
`10= sqrt3 V _(B) implies V _(B) = (10)/( sqrt3)`