Question

7. A car is travelling along a road at 30 ms when a pedestrian steps into the road 55 m ahead. The

Answer 1

Answer: Car collide with man

Explanation:

Given

Speed of car is $u=30\ m/s$

Distance of the man from the car is $s=55\ m$

Reaction time $t_r=0.5\ s$

Rate of deceleration $a_d=-10\ m/s^2$

Distance traveled in the reaction time $d_o=30\times 0.5=15\ m$

Net effective distance to cover $d=55-15=40\ m$

Distance required to stop the car

$\Rightarrow v^2-30^2=2(-10)(s)\\\Rightarrow 0-900=-20s\\\Rightarrow s=45\ m$

Require distance is more than that of net effective distance. Hence, car collides with the man.