Contemporary science issues
Lesson 18: Car Crash Safety
© 2006 Gatsby Technical Education Projects
Car Crash Safety!
How Can We Reduce the Effects
of Collisions?
Notice that the passenger
compartment is not
damaged. Why?
Again, the impact area collapses but
the passenger area remains intact.
Crumple Zones
• Regions around a vehicle which are made
weak deliberately
• In a crash, these regions deform before
the passenger ‘capsule’
BUT
• If the passengers aren’t wearing seatbelts…….
…they carry on
moving at the
velocity of the
car before the
impact!
Old-fashioned seat-belts could cause damage
like this. Modern “inertia-reel” belts stretch
slightly before locking
Why should a
stretchy seat belt
cause less damage?
Do they change
your deceleration?
Do they change the
force on you?
Does a crumple
zone or a
stretchy seat belt
make any
difference to your
change of speed
as you crash?
Data from a collision involving a
car without a crumple zone.
Data from a collision involving a
car with a crumple zone.
Time (s)
Velocity (m/s)
Time (s)
Velocity (m/s)
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
16
16
16
16
16
0
0
0
0
0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
16
16
16
16
16
12
8
4
0
0
Questions
• Which graph has the steepest gradient?
• Which graph represents the most rapid
deceleration?
• In which car would you suffer the most damage?
• In which car would you be subject to the bigger
forces during the impact?
• Which collision lasts longer?
• What is the relationship between the length of
the collision and the amount of damage?
Velocity versus Time for Collisions
18
Velocity/metres per second
16
14
12
10
8
6
4
2
0
0
0.05
0.1
0.15
0.2
0.25
0.3
-2
Time/seconds
0.35
0.4
0.45
0.5
Plenary: What do these graphs show?
y
y
A
y
y
x
D
y
x
x
B
E
C
y
x
x
F
x