Chapter 4 - Force and Motion - Learning Path Questions and Exercises - Exercises - Page 136: 26

273N

u=90km/hr=25m/s v=0 time=5.5 s Change in velocity =v-u=0-25=-25m/s Average acceleration =$\frac{change\, in\, velocity}{time}=\frac{-25}{5.5}=-4.55m/s^{2}$ Average force = $mass\times average\, acceleration=60\times4.55=273N$