A man of car90km/h sees light of barrier 40m ahead. Reaction time 0.75 s Acceleration is -10m/s^2 doeshe crash

Question

its a physics question and I want to know if he is going to hit the barrier and what is the max. speed to no hit the barrier

Answer 1

After reaction time, barrier is
40 m - (90,000 m/3600 sec)*0.75 sec = 21.25 m away.

V^2 = Vo^2 + 2*a*d

The car is decelerating to a stop so V = 0. Original velocity, Vo, is 90,000 m/3600 sec and a = -10m/s^2. Solve for d and hope it's less than 21.25 m.

To determine max Vo, set d = 21.25 and solve for Vo.

Answer 2

yes, he does crash