Is the following question technically correct and appropriate to be given to O level students.

1. Car A and Car B is at rest at a traffic light. When the traffic light is green, both cars accelerate uniformly and then travel at a constant speed. At time t=0, car A is travelling at 10 m/s and car B is travelling at 15 m/s, when they see two crashed vehicles blocking the road at 70 m away from car A and 100m away from car B.

Driver in car A takes 3s to apply the brakes and the driver in car B takes 5s.

a) Calculate the thinking distance for car A and car B.

After applying the brakes car A decelerates at 2 m/s2 and car B decelerates at 3 m/s2.

b) Calculate the distance travelled by car A and car B before coming to rest.

c) Calculate the overall stopping distance for both cars.

d) Using the information given in the question and your answers to part c) determine if car A and car B will run into the crashed vehicles. Assume car A and car B are on different lanes of the road.

In USA, a speed limit of 48 km/h is enforced for cars travelling on paved roads.

e) Determine if car A and car B were above speed limit when they spotted the traffic accident.

Driver error or long reaction time was stated as the top factor resulting in approximately 70 percent of the fatal road accidents in a report released by the government of UK.

f) i) State two factors which leads to long reaction time.

ii) How does long reaction time affect the thinking distance and the braking distance?

g) Exceeding speed limit is the second most frequent factor leading to road accidents.

i) How does exceeding speed limit affect the thinking distance and the braking distance?

In theory many of the road accidents can be prevented by applying a large braking force. However in practice a large braking force is undesirable.

h) State an undesirable effect of a large braking force.