83 Coming to a Stop

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83 Coming to a Stop Key Vocabulary braking distance reaction time stopping distance

83 Coming to a Stop Imagine you are driving down a road and see a tree lying across the road What factors do you think affect whether you will be able to stop before you hit the tree? Record your answer in your notebook.

83 Coming to a Stop Read the introduction and look for key ideas This distracted driver could be more likely to get in an accident than an alert driver. He has a longer reaction time than does a driver who is not distracted.

83 Coming to a Stop How does a car’s stopping distance change in different situations? How does this situation affect these cars’ stopping distances?

83 Coming to a Stop Reviewing terms Reaction Time – the time period between the driver’s realization that there is danger ahead and his or her engaging the brakes. Reaction Distance – the distance the car travels during the reaction time. Stopping Distance – the sum of the reaction distance and the braking distance.

83 Coming to a Stop Which of your “stopping factors” affect the reaction distance and which affect the braking distance? The driver is in direct control of two critical factors: Car speed Alertness

83 Coming to a Stop Speed = distance time

83 Coming to a Stop Complete the procedure Use student sheet 83.1, “Stopping Distances in Different Conditions” to record your calculations.

83 Coming to a Stop Review your calculations

83 Coming to a Stop Final graph

83 Coming to a Stop Analysis question 1 Why does stopping distance depend on road conditions?

83 Coming to a Stop Analysis question 2 What might cause: a.slippery road conditions? b.driver distractions?

83 Coming to a Stop Analysis question 3 In which of the three driving situations (alert and dry, alert and slippery, distracted and dry) does it take: a.the least distance to stop? Explain using evidence. b.the most distance to stop? Explain using evidence.

83 Coming to a Stop Analysis question 4 You are alertly driving a car at 40 mph (18 m/s). You come around a bend and see a tree that has fallen across the road 50 meters away. Will you be able to stop before you hit the tree: a.on a dry road? Show your evidence. b.on a wet road? Show your evidence.

83 Coming to a Stop Analysis question 5 Would your answers to Analysis Question 4 change: a.If something were distracting you as you came around the bend? Explain. b.If you were driving 20 mph instead of 40 mph? Explain.

83 Coming to a Stop Analysis question 6 Your friend says that when a car goes twice as fast, the braking distance doubles. Do you agree or disagree? Use evidence from this investigation to support your ideas.

83 Coming to a Stop SCORING GUIDE: Analyzing Data

83 Coming to a Stop Analysis question 7 Create a concept map using the following terms:

83 Coming to a Stop What is the advantage of using tires that grip roads well? Share your ideas with the class.

83 Coming to a Stop How does a car’s stopping distance change in different situations?

83 Coming to a Stop Key vocabulary definitions Braking distance - The distance a vehicle travels from the time the driver applies the brakes until the vehicle comes to a complete stop.

83 Coming to a Stop Key vocabulary definitions Reaction time - The time it takes from the moment a person or an animal recognizes the need to take an action to the moment of initiating the action, such as in the case of a driver seeing an object to avoid and then applying the brakes.

83 Coming to a Stop Key vocabulary definitions Stopping distance - The total distance a vehicle travels during the driver’s effort to bring the vehicle to a halt; distance traveled during the driver’s reaction time plus the braking distance.

83 Coming to a Stop Distracted driver, slippery road The table below shows the stopping distances for a distracted driver on a slippery road. Using the graph you made in this activity, plot this data on your graph. Label the line, “Distracted Driver, Slippery Road.”