During a car crash, the more rapidly a person decelerates, the more likely she is to be injured. A large deceleration is dangerous, even if it lasts for a short time.
Airbags are designed to decrease the magnitude of the deceleration. Before the airbag inflates, the driver continues forward at constant speed. But once the airbag inflates, the driver decelerates gradually, instead of getting thrown into the windshield or steering wheel.
Three different models of airbags were tested using identical crash test dummies. Sensors measured the velocity of the crash test dummy as a function of time, when the car crashed at 20 m/s into a brick wall. The following velocity vs. time graphs resulted. Time
t
= 0 s is the moment the car crashes.
1.
All three airbags are the same size and shape. Which one inflates most quickly?
A.
Airbag 1
B.
Airbag 2
C.
Airbag 3
D.
We cannot determine the answer from the given information.
2.
Let
a
max
denote the largest instantaneous acceleration that the crash test dummy experiences during the crash. The best airbag is the one for which |
a
max
| is as small as possible. Which airbag is best?
A.
Airbag 1
B.
Airbag 2
C.
Airbag 3
D.
We cannot determine the answer from the given information.
3.
For airbag 2, which of the following graphs best represents the
position
of the crash test dummy as a function of time? Let
x
= 0 m be the dummy's position at time
t
= 0 s.
A.
A
B.
B
C.
C
D.
D
4.
For airbag 2, approximately how much distance does the dummy cover between the moment the car crashes and the moment the dummy first makes contact with the airbag?
A.
0.2 m
B.
0.4 m
C.
0.6 m
D.
1.0 m
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