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.
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,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
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, 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 whee
Get the Gizmo ready:
Activity A: Surviving
a crash Click Reset ().
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
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