NumericalModerate1 mark
8(c)(ii)
A certain sound has a frequency of 256 hertz and a wavelength of 1.3 m.
Calculate the speed with which this sound travels.
Topic: Sound and vibrations
Previous-year question practice database
Answer
Exam answer
Given: f = 256 Hz, λ = 1.3 m
The wave equation: v = f λ = 256 × 1.3 = 332.8 m s⁻¹
Speed of the sound = 332.8 m s⁻¹
Explanation
A direct substitution into v = fλ. Keep the units straight — the wavelength is in metres and the frequency in hertz (per second), so the speed comes out in metres per second.
Sanity check: sound in air travels at roughly 330–340 m s⁻¹, so 332.8 is exactly the right size. If your answer comes out in the hundreds of thousands you have probably confused it with the speed of light; if it comes out as 197 you have divided instead of multiplied.
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