1. 1
   A driving instructor is teaching a student about reaction times. The student is asked to react to a red light appearing on a screen by pressing a button as quickly as possible. This test is repeated twice: once with the student having consumed no alcohol, and again after the student has consumed a small amount of alcohol. The instructor explains that this reaction-time test represents the 'thinking' part of stopping a car during real driving.

   (a)

   Which equation correctly describes how stopping distance is calculated?

   [1 mark]

   • Astopping distance = thinking distance + braking distance
   • Bstopping distance = thinking distance × braking distance
   • Cstopping distance = braking distance − thinking distance
   • Dstopping distance = reaction time × braking distance

   (b)

   Based on the scenario, which of the following would most likely increase the student's thinking distance while driving?

   [1 mark]

   • Adriving on a dry road rather than a wet road
   • Breducing the car's speed
   • Cimproving the tread on the car's tyres
   • Dconsuming alcohol before driving

   (c)

   The student's reaction time was measured as 0.4 s with no alcohol and 0.7 s after a small amount of alcohol. If the car is travelling at 20 m/s, calculate the increase in thinking distance caused by the alcohol.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A safety engineer is investigating how road surface condition affects the distance needed for a car travelling at 18 m/s to stop. The engineer uses the same car and the same driver for both tests, keeping the driver's reaction time constant. The car is first tested braking on a dry road, then tested braking on a wet, icy road at the same speed.

   (a)

   Which factor is being varied between the two tests?

   [1 mark]

   • Athe mass of the car
   • Bthe driver's reaction time
   • Cthe friction between the tyres and the road surface
   • Dthe speed of the car

   (b)

   Compared with the dry road, the braking distance on the icy road will be:

   [1 mark]

   • Ashorter, because friction between the tyres and road is increased
   • Blonger, because friction between the tyres and road is reduced
   • Cthe same, because the speed is unchanged
   • Dshorter, because the driver's reaction time decreases on ice

   (c)

   Explain, in terms of the forces acting on the car, why the braking distance is greater on the icy road than on the dry road.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A car of mass 1200 kg is travelling at 24 m/s along a level road when the driver applies the brakes and the car comes to rest after travelling a braking distance of 36 m.

   (a)

   Calculate the deceleration of the car, using the equation $v^2 - u^2 = 2 \times a \times x$.

   [3 marks]

   (b)

   Calculate the braking force needed to produce this deceleration. Then explain why, if the car's initial speed had instead been much higher, an even greater braking force would be needed to stop the car within a similar distance.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A road safety charity is designing a campaign to explain to new drivers why speed limits are lower near schools than on motorways. As part of the campaign, the charity carries out an investigation: volunteers react to a hazard appearing on a driving simulator screen, and their reaction time is measured. The test is then repeated with the same volunteers while they perform a mental arithmetic task at the same time, to simulate a distraction such as using a mobile phone.

   (a)

   Evaluate this investigation, discussing whether it provides valid evidence for how distraction affects reaction time and stopping distance, and suggest one improvement to the method.

   [6 marks]

   (b)

   Using ideas about thinking distance, braking distance and forces, explain why speed limits are set lower near schools than on motorways, and why this reduces the risk of harm to pedestrians.

   [6 marks]

   Total for question 4: 12 marks

End of questions