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GCSE Questions - Waves

Q7. P-waves and S-waves are two types of seismic wave caused by earthquakes.

(a) Which one of the statements about P-waves and S-waves is correct? Tick one box.

Statement
Tick here
P-waves and S-waves are transverse.  
P-waves and S-waves are longitudinal.  
P-waves are transverse and S-waves are longitudinal.  
P-waves are longitudinal and S-waves are transverse.

See the notes on P-Waves and S-Waves

[1 mark]

(b) Seismometers on the Earth's surface record the vibrations caused by seismic waves.

The diagram shows the vibration recorded by a seismometer for one P-wave.

(i) Calculate the frequency of the P-wave shown above

There are four full waveforms in the trace - see diagram.

T = 10/4 = 2.5s

f = 1/T

f = 1/2.5 = 0.40 Hz

[4 marks]

(ii) Write down the equation which links frequency, wavelength and wave speed.

wavespeed = frequency x wavelength

v = fλ

[1 mark]

(iii) The P-wave shown above is travelling at 7200 m/s.

Calculate the wavelength of the P-wave.

λ = v/f

λ = 7200/0.40

λ = 18 000 m

[3 marks]

(Total 9 marks)