Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 61: 18

$a). 6 m/s$ $b). 18 m/s$

$x=3\times t^{2}$ a). average velocity for $\Delta t = 2.0 s - 0 s$ = $\frac{3\times 2^{2}-0}{2.0 - 0 }=6 m/s$ b). average velocity for $\Delta t = 4.0 s - 2.0 s$ = $\frac{3\times 2^{4}-3\times2^{2}}{4.0 - 2.0 }=\frac{48-12}{2}=18 m/s$