Wavelength and frequency

3 marks · Easy

A boat produces waves in a harbour. Each wave crest is 7 metres apart and 4 waves pass a fixed point every 14 seconds.

(a)

Calculate the frequency of the waves.

[1 mark]

(b)

Calculate the speed of the waves.

[2 marks]

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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(a) 0.286 Hz

(b) 2.0 m/s

Show mark scheme and worked solution

Marking points

M1 (a) · 1 mark · Correct calculation of frequency (number waves ÷ time).

M1 (b) · 1 mark · Correct use of wave speed equation with candidate's frequency and given wavelength. (follow-through)

A1 (b) · 1 mark · Correct answer for speed with appropriate units. (follow-through)

Worked solution

(a) Frequency = Number of waves / Time = 4 / 14 = 0.286 Hz

(b) Wave speed = frequency × wavelength = 0.286 × 7 = 2.0 m/s