$16\mathrm{.}86$ The total external force on the $2-$kg object is given as a function of time by $$F $=2$ti $+4$j $1$N$2.$ ject$$s position and velocity are r $=0$ At time v $=0.$ t$1=0,$ the ob and $($a$)$ Use Newton$$s second law to determine the object$$s velocity v and position r as functions of time. $($b$)$ By integrating r $*$F t$2=6$ s$,$ with respect to time from to determine the angular impulse about O exerted on the object during this interval of time. t$1=0($c$)$ Use the results of part $($a$)$ to determine the change in the ob ject$$s angular momentum from t$1=0$ y O r to t$2=6$ s