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Water waves are produced in the tank - Edexcel - GCSE Physics: Combined Science - Question 2 - 2016 - Paper 1
Question 2
Water waves are produced in the tank. The shadow of the waves is projected onto the screen below the tank. The waves appear to move in the direction of the arrow. (... show full transcript
Worked Solution & Example Answer:Water waves are produced in the tank - Edexcel - GCSE Physics: Combined Science - Question 2 - 2016 - Paper 1
Step 1
Describe how to determine the frequency of the waves.
Answer
To determine the frequency of the water waves, first measure the time taken for a specific number of wave crests to pass a point (this determines the period). Count the number of waves that pass that point in a certain time interval, say 10 seconds. Then, the frequency (f) can be calculated using the formula:
where n is the number of waves and t is the time in seconds. This gives the frequency in Hz.
Step 2
What is the approximate wavelength of the waves as seen on the screen?
Answer
The screen is 80 cm long. If we observe the shadow pattern of the waves, we can visually estimate the distance between the wave peaks to find the wavelength. For this problem, after evaluating the shadow on the screen, the approximate wavelength can be concluded to be 8 cm.
Step 3
Which of these is a reason why the estimate is not correct?
Answer
The reason why the estimate of speed 75 cm/s might be incorrect is that A the student used a ruler without mm markings. This could lead to inaccuracies in measuring the wavelength and therefore affect the calculation of speed.