$2022\mathrm{.}10\mathrm{.}05$

Problem $1(15$ pts$)$

The end point $B$ of a missile launcher is originally $6$ m from fixed point $A.$ When the missile

launcher working, B has a constant radial acceleration $r^{}=-1\mathrm{.}5\frac{m}{s^2}$ and a constant angular

acceleration ${}^{}=0\mathrm{.}6ra\frac{d}{s^2}.$ Knowing that missile launchers initially existed horizontally, at $t=$

$2$ s $,$ determine

$($a$)$ the velocity of point $B.$

$($b$)$ the acceleration of point $B.$

$($c$)$ the radius of curvature of the path of

point B$.$