Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 61: 17

a). $x=0$, b). $14 \,m.$

$x=at-bt^{2}$ $a=10 m/s, b=0.5m/s^{2}$ a) at t=0, $x=0-0=0$ b).at t=2, $x=2a-4b=20\,m-2\,m=18\,m$ at t=4, $x=4a-16b=40\,m-8\,m=32\,m$ The particle's displacement in between t=2 s and t=4 s is 32-18=14 m.