Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 62: 40

$-1.54m/s^{2}$

$v^{2}=u^{2}+2aS$ $a=\frac{v^{2}-u^{2}}{2S}$ $v=40 km/hr=40\times\frac{1000m}{3600s}=11.11 m/s$ $u=60 km/hr=60\times\frac{1000m}{3600s}=16.67 m/s$ Therefore, $a=\frac{11.11^{2}-16.67^{2}}{100} m/s^{2}=-1.54m/s^{2}$