Concussions in professional athletes
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- Concussions in professional athletes
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Concussions in professional athletes
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[ID] => 556512
[post_author] => 12815
[post_date] => 2025-01-09 07:20:37
[post_date_gmt] => 2025-01-09 12:20:37
[post_content] => Practice Passage (Question 1-5)
*This passage is the property of Khan Academy and has been reformatted into an AAMC-style interface in their entirety by MedLife Mastery. MedLife Mastery does not endorse and is not an affiliate of Khan Academy.
Researchers are trying to develop ways to reduce the frequency of concussions among professional sports athletes by producing helmet padding that better protect the athletes from direct hits to the head. One way to accomplish this is to try and decrease the magnitude of the acceleration of the struck athlete’s brain.
To test the effect that different padding materials have on the acceleration of a human brain, the researchers used a “dummy” head with ballistic gel “dummy” brain with motion sensors embedded within it. They put the “dummy” head inside the helmets and struck the helmets with a blow from a spring-fired piston. During the collision the researchers monitored the speed of the “dummy” brain as a function of time. A working assumption that the researchers are using is that the worst concussions are caused by the largest instantaneous value (i.e. value at a particular moment in time) of the acceleration of the brain.
The data collected in the experiment is shown below.
Figure 1. The velocity vs time graph of the dummy brain. Each line represents different padding used by the researchers.
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[question] => Describe the acceleration experienced by the “dummy” brain during the 5 millisecond interval when using padding D.
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[answer] => 4
[description] => Reason for the Correct Answer:
The definition of acceleration is a = Δv/Δt.
The slope of a velocity vs. time graph gives the acceleration.
The velocity graph for padding D starts with a steep slope (large magnitude) and ends with a shallow slope (small magnitude).
Since the slope of the velocity graph for padding D is decreasing, the acceleration is decreasing.
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[answers] => Array
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[0] => Array
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[each_answer] => A. Acceleration is constant
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[each_answer] => B. Acceleration increases then decrease
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[2] => Array
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[each_answer] => C. Acceleration increases
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[each_answer] => D. Acceleration decreases
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[1] => Array
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[quiz_unique_key] => 3873426850
[question] => At what time would the athlete most be in danger during the 5 millisecond interval when using padding C?
[value] => Array
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[answer] => 1
[description] => Reason for the Correct Answer:
The definition of acceleration is a = Δv/Δt.
The slope of a velocity vs. time graph gives the acceleration.
Compare the slopes at different times of the graph for padding C to find the time with the steepest slope at a single point.
Since the slope of the velocity graph for padding C is steepest at t=1 millisecond, that is where the acceleration is largest and the point where the athlete would be in the most danger.
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[answers] => Array
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[each_answer] => A. 1 millisecond
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[each_answer] => B. 2 milliseconds
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[each_answer] => C. 4 milliseconds
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[each_answer] => D. 3 milliseconds
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[2] => Array
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[quiz_unique_key] => 83407773
[question] => Which helmet is most dangerous to athletes?
[value] => Array
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[answer] => 4
[description] => Reason for the Correct Answer:
The definition of acceleration is a = Δv/Δt.
The slope of a velocity vs. time graph gives the acceleration.
Compare the slopes at different times of all the graphs to find the graph with the steepest slope at a single point.
The slope of the velocity graph for padding D between 0 and 1 milliseconds is steeper than any other graph, so it has the largest instantaneous acceleration.
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[answers] => Array
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[each_answer] => A. Padding A
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[each_answer] => B. Padding B
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[each_answer] => C. Padding C
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[each_answer] => D. Padding D
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[quiz_unique_key] => 2261298308
[question] => Which padding provides the most safety for athletes?
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[answer] => 1
[description] => Reason for the Correct Answer:
The brain is harmed by large values of acceleration.
The slope of a velocity vs. time graph gives the acceleration.
Compare the slopes at different times of all the graphs to find the graph with the least acceleration.
The slope of the velocity graph for padding A is less than any other graph, so it provides the least acceleration and the most safety.
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[answers] => Array
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[0] => Array
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[each_answer] => A. Padding A
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[each_answer] => B. Padding B
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[each_answer] => C. Padding C
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[each_answer] => D. Padding D
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[quiz_unique_key] => 2261298308
[question] => Calculate the acceleration of the “dummy” brain when using padding B?
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[answer] => 3
[description] => Reason for the Correct Answer:
The definition of acceleration is a = Δv/Δt
The slope of a velocity vs. time graph gives the acceleration.
Choose two points on the graph for padding B and solve for slope by using (v₂-v₁)/(t₂-t₁)
Plug in v₂=1.2m/s, t₂=5millisec and v₁=0m/s, t₁=0sec into the formula for slope to get (1.2m/s)/(0.005sec) = 240 m/s
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[each_answer] => A. 145 m/s²
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[each_answer] => B. 78.3 m/s²
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[2] => Array
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[each_answer] => C. 240 m/s²
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[3] => Array
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[each_answer] => D. 490 m/s²
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[post_title] => Concussions in professional athletes
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