To calculate the speed of the waves, we need to follow these steps:
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Calculate the frequency of the waves: Frequency (Hz) = Number of waves / Time (s)
We know that 2 waves pass by in 4 seconds: \[ \text{Frequency} = \frac{2 \text{ waves}}{4 \text{ seconds}} = 0.5 \text{ Hz} \]
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Determine the wavelength: The distance between each wave crest (wavelength) is given as 2 meters.
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Calculate the wave speed using the wave speed formula: Wave speed (m/s) = Frequency (Hz) × Wavelength (m) \[ \text{Wave speed} = 0.5 \text{ Hz} \times 2 \text{ m} = 1 \text{ m/s} \]
The speed of the waves is 1 m/s. Therefore, the correct answer is:
A 1 m/s.