Stopping distance and road safetyIB MYP Physics: Flashcards

Exam questions on Stopping distance and road safety

1. A driver in Cairo is travelling along a straight road when a child runs out in front of her car. There is a short delay before she presses the brake pedal, and then the car travels further before it stops.
   Explain why drinking alcohol increases the stopping distance of a car.2 marks
2. A driving test centre in Auckland tests a car on a dry, level road. At 10 m/s the car has a braking distance of 12 m when the brakes apply a constant force. A learner driver has the same reaction time of 0.8 s whatever her speed.
   Predict the braking distance of the car at 20 m/s on the same road. Explain your prediction in terms of kinetic energy.2 marks
3. Students in Lagos investigate how the road surface affects the braking distance of a model car. The car is released from the same point on a ramp, so it reaches the same speed at the bottom, and then slides to a stop across a flat surface with its wheels locked. The braking distance was 0.90 m on a smooth plastic sheet, 0.50 m on a wooden board, 0.30 m on carpet and 0.20 m on sandpaper.
   State the independent variable, the dependent variable and one control variable in this investigation.3 marks