Unit: Waves
Year: 1997 Question#: 40
Question: In the diagram below, a water wave having a speed of 0.25 meter per second causes a cork to move up and down 4.0 times in 8.0 seconds. What is the wavelength of the wave?
(1 ) 1.0 m
(2 ) 2.0 m
(3 ) 8.0 m
(4 ) .50 m
What is this question really asking?
Explanation by: Jennifer I
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Answer 1
1.0 m
INCORRECT
This answer can be obtained by simply dividing the cycles by the speed of the wave. This however does not produce the correct units and doesn't deal with the frequency of the wave.
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Answer 2
2.0 m
INCORRECT
If you used the formula
then it appears that you may have either been careless in you division, or your
algebraic manipulation of the formula. return to top
Answer 3
8.0 m
INCORRECT
8.0 meters is the speed of the wave, the number of cycles and the time to complete these cycles, this answer doesn't use a formula and doesn't lead to the correct units.
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Answer 4
.50m
CORRECT
Velocity is a speed and a direction ( a vector quantity). Since
a direction is not needed for this problem, speed can be substituted.f=cycles / unit time = 4.0 cycles / 8.0 sec = .5 hertz
wavelength= (velocity) / (frequency) wavelength= .25m/s / .5 hertz = .50 m
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What's this question really asking?
What is the wavelength of a wave with a speed of .25m/s that completes 4 cycles in 8 seconds. return to top
