Student Exploration: Crumple Zones
Vocabulary: acceleration, airbag, collision avoidance system, crash test dummy, crumple zone,
force, kinetic energy, Newton’s laws of motion, safety cell, seat belt, work, work-energy theorem
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
Two b...
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
Two burglars run down an alley at night, trying to escape the cops.
Jack is carrying a rigid metal safe. Jill is carrying an armful of
antique quilts. In the pitch dark, they both collide headlong into a
concrete wall.
1. Who do you think will be hurt more in the collision, and why?
I think the thief with the metal safe will be hurt more since
because the quilt with act like a cushion whereas the safe
would just increase the impact on thief
2. During a car crash, what features of the car might act like either Jack’s safe or Jill’s quilts?
During a car crash, the airbag would act like Jill's quilts since it decreases the impact
on his body. If the airbag wasn't present, the steering wheel would behave like Jack's
safe since the impact would be much harder as compared to the airbag. the seat belt
prevents the face from hitting the steering wheel too!
Gizmo Warm-up
When cars were first invented, the safety of passengers was
not a great concern. As vehicles grew larger and faster,
accidents became more deadly. Safety features went from
being a rare luxury to a legal requirement. In the Crumple
Zones Gizmo, you will design cars that will help a crash test
dummy survive a collision.
1. To begin, do not make any changes to the DESIGN tab of the Gizmo. Select the CRASH
TEST tab, and click Play ( ). After the crash, click Slo-mo replay. What happens?
Due to the absence of the seat belt, airbag or the collision avoidance system, the
crash test dummy jerks forward and hits the steering wheel due to Newtons first law
of motion (Inertia)
2. Select the RESULTS tab to read about the results of the crash. Do you think a passenger
would have survived this car crash? Explain. The results say the dummy hit the steering
wheel. The dummy wasn't wearing a seat belt either which means the car decelerated
at about 20000m/s^2. So I don't think the passenger would survive the crash.
2019
, Get the Gizmo ready:
Activity A:
Click Reset ( ).
Surviving a crash
On the DESIGN tab, check that Sedan is selected.
Introduction: Modern vehicles contain features designed to keep passengers safe in a crash.
The crumple zone in the front of the car slows the car gradually and increases stopping time.
The safety cell is a rigid cage that prevents passengers from being crushed. Inside, seat belts
and airbags prevent the driver from hitting the windshield, steering wheel, or dashboard.
Question: How does a crumple zone help protect a passenger?
1. Make a hypothesis: On the DESIGN tab, look at the parameters you can control. What
settings do you think will make the safest car? Set up the Gizmo, and then fill in below.
Crumple zone length: 120 Crumple zone rigidity: 800 Safety cell rigidity: 450
Seat belt present? yes If present, seat belt stiffness: 15
Air bag present? yes If present, air bag rigidity: 8
2. Test: On the CRASH TEST tab, check that the Car 1 speed is 16 m/s, or about 35 miles per
hour (mph). Click Play. After the crash, select the RESULTS tab.
19%
A. By what percentage did the crumple zone deform? Safety cell? 20
B. Did the dummy hit the steering wheel? no
C. What was the maximum force on the dummy? 15.41 kN
D. How likely was the dummy to survive? 98%
In this simulation, forces are measured in kilonewtons (kN). One kilonewton is equal to 1000
newtons, or the force of a 225-pound (102 kg) person standing on your chest. While many
factors affect survival, only the maximum force and safety cell collapse are considered here.
3. Experiment: On the DESIGN tab, set the Crumple zone length to 100 cm and the Safety
cell rigidity to 2000 kN. Set the Seat belt stiffness to 50 kN/m and turn off the Airbag. For
each Crumple zone rigidity setting, run a 16 m/s crash test and enter the results below.
Crumple zone Crumple zone Dummy Max. force on Likelihood of
rigidity deformation displacement dummy survival
100 kN 100% 1.42 m 20.88 kN 87%
200 kN 93% 1.21 m 14.25 kN 100%
300 kN 62% 1.02 m 19.88 kN 89%
400 kN 47% 0.93 m 23.02 kN 82%
(Activity A continued on next page)
2019
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