Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 62: 36

180s

$72 km/hr=72 \times\frac{1000}{3600}m/s=20m/s$ $v=u+at$ During decelerating, $t=\frac{v-u}{a}=\frac{0-20}{-1}=20s,$ Then stoppage time is $2min=120s$, During accelerating, $t=\frac{v-u}{a}=\frac{20-0}{0.5}=40s,$ So, total time = $20+120+40=180s$