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.

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Read the introduction and look for key ideas

This distracted driver couldbe more likely to get inan accident than an alertdriver. He has a longerreaction time than does adriver 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.

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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

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Speed = distance

time

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Complete the procedure

Use student sheet 83.1, “Stopping Distances in

Different Conditions” to record your calculations.

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Review your calculations

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Final graph

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Analysis question 1

Why does stopping distance depend on road conditions?

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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.

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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.

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SCORING GUIDE: Analyzing Data

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Analysis question 7

Create a concept map using the following terms:

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What is the advantage of using tires that grip roads well?

Share your ideas with the class.

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How does a car’s stopping distance change in different situations?

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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.”