Transcript Activity 83 Coming to a Stop

Activity 83
Coming to a Stop
Challenge: How does a car’s stopping distance
change in different situations?
Key Vocabulary
• Reaction Time – the time period
between the driver’s realization that
there is danger ahead and his/her
engaging the brakes
• Stopping Distance – the sum of the
reaction time and the braking
distance
Getting started…
• Imagine drawing down a road, and
seeing a tree lying across the road.
• What factors do you think will affect
whether you will be able to stop
before you hit the tree?
• Car Speed, how far away the tree is,
condition of the driver, vehicle
equipment, and road conditions will
contribute to whether or not you will
hit the tree.
• Which of your stopping factors affect
the reaction distance and which
affect the braking distance?
• The driver is in direct control of 2
critical factors:
– Car speed
– Alertness
Doing the Activity…
• Read the Introduction on page 45
• Follow the Procedure Steps 1-3
– Copy the equations for reaction
distance and stopping distance in your
notebooks!
– Label your graphs correctly!
• When you are finished, answer
analysis # 1-5.
Check your Results:
Analysis Questions
1. Stopping distance depends on road
conditions because friction is what
causes the car to stop. Road
conditions affect the amount of
friction between the road and the
tires. Surfaces with less friction are,
by definition, more slippery.
2. Snow, ice, gravel, and oil can cause
slippery road conditions.
Such things as cell phones, music,
passengers, eating, drinking, and
other vehicles can distract the driver
3.
a. At every speed, the stopping distance for
“alert and dry” was less than either of the
other sets of conditions.
b. What can take the most distance to stop
will depend on driving speed. Speeds
less than 9 m/s or less the stopping
distance for ‘distracted and dry” is more
than either of the other sets of conditions.
Speeds greater than 9 m/s , the stopping
distance for “alert and slippery” is more
than either of the other sets of conditions.
4.
a. At 40 MPH it takes 46 meters for an alert
driver to stop a car on dry pavement.
Under these conditions my car would
stop 4 meters from the tree.
b. Wet roads are slippery. At 40 MPH on a
slippery road, it takes an alert driver 81
meter to stop a car. Under these
conditions my car would hit the tree.
5.
a. If I were distracted, it would take 73
meters to stop in dry conditions, and I
would hit the tree. In wet conditions, I
would hit the tree at a higher speed than
if I were not distracted.
b. If I were driving 20 MPH, it would take 18
m to stop on a dry road and 27 m to stop
on a slippery road. I wouldn’t hit the tree
in either dry or wet conditions.