Answer to Question #347283 in Physics for maria

Question

When the driver of a car travelling at 72km/h suddenly sees a pedestrian in front of the car , he applies the brakes. Consider the reaction time of the driver is 0.2s. if the maximum deceleration that the brakes can produce is 20m/s², Find the maximum stopping distance for the car

Answer 1

$$d=d_1+d_2=vt+\frac{v^2}{2a}$$

$$d={\rm 20\: m/s*0.2\: s+(20\: m/s)^2/(2*20\: m/s^2)}\\ =14\:\rm m$$