MOVEMENT AND CHANGE

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MOVEMENT AND CHANGE

• Stopping Distances

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Lesson Aims

• Consolidate understanding of how to interpret
  speed-time graphs.
• Understand what makes up the stopping distance
  of a vehicle.
• Know the factors that affect stopping distances

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HOMEWORK

• Make sure your homework booklet is inside your
  exercise book. If you have not stuck it in your
  book write your name on it!

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Speed Time Graphs

• To show your understanding of this topic
• Answer question number 1 2 off page 131 of
  Physics text book
• It should take you about 13 minutes to do this
  including the time taken to draw a graph

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Stopping distance
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Stopping distances

• Accidents on motorways often involve vehicles of
  great mass travelling at large speeds.
• The forces involved when these vehicles suddenly
  stop are enormous.

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Stopping distances

• Compare the following vehicles.
• A car travelling at 25 m/s
• An identical car travelling at 35 m /s
• A coach travelling at 20 m / s
• Which will be the hardest to stop?
• Which will need the largest force to stop?

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Stopping safety
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Stopping safety

• Thinking distance
• There is always a short time between our eyes
  seeing that something has to be done and our
  brains actually moving our muscles. This time is
  called the reaction time

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• For a healthy person this is usually about half
  a second (it is less for younger people and
  longer for older people).
• The thinking distance is how long a car will
  travel during a drivers reaction time.
• The faster a car is travelling, the greater the
  thinking distance.

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Stopping distances

• What factors do you think determine how long it
  takes a car to stop?
• The mass of the vehicle
• The speed of the vehicle
• The drivers reaction time

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Stopping distances

• The greater the mass of a vehicle, the longer
  its stopping distance.
• The greater the speed of the vehicle, the longer
  its stopping distance.
• The longer the drivers reaction time, the longer
  its stopping distance

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Question time!

• Your teacher will now give you a sheet with some
  information and questions on.
• Stick this sheet in your exercise books and
  answer the questions.
• This task should be completed as part of your
  next homework.