Photo AI
A student made water waves in a ripple tank - AQA - GCSE Physics Combined Science - Question 3 - 2021 - Paper 2
Question 3
A student made water waves in a ripple tank. 1. Describe how the frequency and wavelength of the water waves in the ripple tank can be measured accurately. 2. Dete... show full transcript
Worked Solution & Example Answer:A student made water waves in a ripple tank - AQA - GCSE Physics Combined Science - Question 3 - 2021 - Paper 2
Step 1
Describe how the frequency and wavelength of the water waves in the ripple tank can be measured accurately.
Answer
To measure the frequency and wavelength of water waves in a ripple tank:
-
Wavelength Measurement:
- Place a meter rule at the side of the screen perpendicular to the wave fronts.
- Measure the distance between two consecutive wave fronts using the meter rule.
- Take a photograph of the shadow of the wave fronts to ensure accurate recording.
-
Frequency Measurement:
- Count the number of waves that pass a fixed point in a set time interval (e.g., 10 seconds).
- Use a stopwatch to time how long it takes for these waves to pass that point.
- Calculate the frequency by dividing the total number of waves by the time taken.
Step 2
Determine the mean wave speed.
Answer
To determine the mean wave speed:
-
Calculate Mean Values:
-
The mean frequency can be calculated from the given readings:
\ ext{Mean frequency} = rac{9.8 + 9.4 + 9.3}{3} = 9.5 , ext{Hz}
-
The mean wavelength can be calculated as:
\ ext{Mean wavelength} = rac{1.7 + 2.2 + 2.1}{3} = 2.0 , ext{cm} = 0.020 , ext{m}
-
-
Calculate Wave Speed:
-
Use the wave speed formula:
[ v = f imes \lambda ]
-
Substituting the mean values:
[ v = 9.5 , \text{Hz} \times 0.020 , \text{m} = 0.19 , \text{m/s} ]
-
Step 3
What is the advantage of taking repeat readings and then calculating a mean?
Answer
The advantage of taking repeat readings is that it reduces the effect of random errors that may occur in individual measurements. By averaging multiple readings, we achieve a more accurate estimate of the true value, ensuring that anomalous readings can be discarded before calculating the mean.
Step 4
Explain how the depth of the water is affected by the depth of the water in the ripple tank.
Answer
The depth of water affects the speed and wavelength of waves:
-
Depth and Speed Relationship: Deeper water allows waves to travel faster, which is due to reduced friction and more efficient energy transfer.
-
Wavelength Relationship: As the depth increases, the wavelength of the waves also increases, assuming the frequency remains constant. This is because the speed of the wave is directly proportional to its wavelength given by the equation:
[ v = f \times \lambda ]
Here, when frequency (f) is constant, an increase in wave speed (v) from greater water depth leads to a longer wavelength (\lambda).