2.4 Stopping Distances

Some sources claim that self-driving cars will be available by the year 2040.

Write down the equation relating reaction time, reaction distance and vehicle speed.

It takes the average person 1.6 s to hit the brakes if somebody walks into the road in front of the car. 

Calculate the reaction distance in this scenario at a speed of 30 m/s.

The braking distance for a family car at 30 m/s is 75 m.

Calculate the stopping distance at this speed.

stopping distance = .................................... m

A self-driving car has an average "reaction time" of 0.5 s. 

Calculate the stopping distance of a self-driving car with the same brakes as in part (c) travelling at 40 m/s.

stopping distance = .................................... m

Define reaction time.

Student A holds a 30 cm ruler. 

Students B and C take turns to hold their hands under the ruler and try to catch it when student A lets go.

They use position of their fingers on the ruler to calculate their reaction times. 

Name one variable the students should control.

Student A holds the ruler at the 0 cm end. 

Student B catches the ruler at 28 cm. Student C catches the ruler at 22 cm.

State which student has the faster reaction time. Explain your answer.