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?
Jack because F=ma so the bigger the mass is the bigger
the force in which the impact will occur.
2. During a car crash, what features of the car might act like either Jack’s safe or Jill’s quilts?
The weight of the car and all of it posterior structure is going to be Jack’s safe and Jill’s
quilts is going to be the air bags.
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?
Slo-mo replay shows what’s happening to the dummy and the car when it crashes.
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. He wouldn’t survive because he decelerate
2019
, much faster than the car did and max force was a lot, therefore he would’t survive due to
trauma to head and torso because it would hit its head very hard against the steering wheel.
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: 120cm Crumple zone rigidity: 200kN Safety cell rigidity: 4000kN
Seat belt present? Yes, If present, seat belt stiffness: 75kN/m
Air bag present? Yes, If present, air bag rigidity: 40kN
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.
A. By what percentage did the crumple zone deform? 100% Safety cell? 2%
B. Did the dummy hit the steering wheel? No
C. What was the maximum force on the dummy? 17.29kN
D. How likely was the dummy to survive? 100%
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% 1.42m 20.88kN 87%
200 kN 93% 1.21m 14.25kN 100%
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