Answer
$s(t)=4.9t^2-3t$
Work Step by Step
Here, $a=9.8; v(0)=-3;s(0)=0$
Since, the derivative of velocity is acceleration, thus $v(t)=9.8t+C$
Since, we have $v(0)=-3$ This implies that $-3=9.8(0)+C$ or, $C=-3$
So, $v(t)=9.8t-3$
Since,we know that the derivative of position $s(t)$ is velocity, so we have: $s(t)=4.9t^2-3t+C'$
Since, we have, $s(0)=0$ Therefore, $0=4.9(0)^2-3(0)+C'$ or, $C'=0$
Hence, $s(t)=4.9t^2-3t$