Reaction Time
Q1.
Two students investigated reflex action times.
This is the method used.
1.      Student A sits with her elbow resting on the edge of a table.
2.      Student B holds a ruler with the bottom of the ruler level with the thumb of Student A.
3.      Student B drops the ruler.
4.      Student A catches the ruler and records the distance, as shown in the diagram below.
5.      Steps 1 to 4 were then repeated.
 
(a)     Suggest two ways the students could improve the method to make sure the test would give valid results.
1. _________________________________________________________________
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2. _________________________________________________________________
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(2)
(b)     The table below shows Student A’s results.
 
Test Number	Distance ruler dropped in mm	
1	117	
2	120	
3	115	
4	106	
5	123	
6	125	
7	106	
What is the median result?
 
Tick one box.	 	
106		
115		
116		
117		
123		
(1)
(c)     The mean distance the ruler was dropped is 116 mm.
Calculate the mean reaction time.
Use the equation:
reaction time in s =  
Give your answer to 3 significant figures
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Mean reaction time = ______________________ s
(3)
(d)     The students then measured Student A’s reaction time using a computer program.
This is the method used.
1.       The computer shows a red box at the start.
2.       As soon as the box turns green the student has to press a key on the keyboard as fast as possible.
3.       The test is repeated five times and a mean reaction time is displayed.
Student A’s mean reaction time was 110 ms.
Using a computer program to measure reaction times is likely to be more valid than the method using a dropped ruler.
Give two reasons why.
1. _________________________________________________________________
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2. _________________________________________________________________
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(2)
(e)     A woman has a head injury.
Her symptoms include:
•        finding it difficult to name familiar objects
•        not being able to remember recent events.
Suggest which part of her brain has been damaged.
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(1)
(f)     A man has a head injury.
He staggers and sways as he walks.
Suggest which part of his brain has been damaged.
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(1)
(Total 10 marks)