$3.($a$)$ If a cartesian coordinate point is given as $($Px $=0\mathrm{.}5,$ Py $=1\mathrm{.}5,$ Pz $=1)$

then find out the corresponding cylindrical coordinates $($$,$$,$ z$)$ and

spherical coordinates $($r$,$ $,$$).$

$4$

$3.($b$)$ Find out the projection of unit vector U $=0\mathrm{.}3$i $+\mathrm{.}12$j $+0\mathrm{.}8956$k on a

vector V $=3\mathrm{.}2$i $+1\mathrm{.}6$j $0\mathrm{.}8$k$.$ Also, calculate the torque produced by a

$1\mathrm{.}5$kg force in the direction of U which is being acted upon vector V$.$