Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 62: 41

$a). 81.4km/hr$ $b). 0.797s$

$100km/hr=100\times\frac{1000m}{3600s}=27.78s$ a). $v^{2}=u^{2}+2aS$ $v^{2}=27.78^{2}-2\times 6.5\times 20$ $v=22.6m/s=22.6\times \frac{3600}{1000}=81.4 km/hr$ b).$v=u+at$ $t=\frac{v-u}{a}=\frac{22.6-27.78}{-6.5}=0.797s$