A physics teacher demonstrates a centripetal force by swinging a bucket of water in the vertical direction. Find the minimum speed that professor must swing the bucket at the top of the circle if he is not to get drenched? $($Consider that his arm is $1$ m long.$)$

Group of answer choices

$4\mathrm{.}1$ m$/$s

$2\mathrm{.}1$ m$/$s

$1\mathrm{.}1$ m$/$s

$3\mathrm{.}1$ m$/$s

$5\mathrm{.}1$ m$/$s