A stone is tied to a string of length l and is whirled in a vertical circle with the other end of the string as the centre. At a certain instant of time, the stone is at its lowest position and has a speed u. The magnitude of the change in velocity as it reaches a position where the string is horizontal (g being acceleration due to gravity) is

Options

A. `sqrt(2(u^(2)-gl))`
B. `sqrt(u^(2)-gl)`
C. `u-sqrt(u^(2)-2gl)`
D. `sqrt(2gl)`

Answer

A