The wave equation
4 marks · NormalA student investigates water waves using a ripple tank. The student measures that 12 complete waves pass a point in 6.0 s. The wavelength of each wave is 25 cm.
Calculate the frequency of the waves.
Calculate the speed of the waves. Give your answer in m/s.
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.
Show answer
(a) 2 Hz
(b) 0.50 m/s
Common mistakes: Not converting cm to m
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Uses frequency = number of waves / time (12/6).
A1 (a) · 1 mark · Frequency is 2 Hz.
M2 (b) · 1 mark · Converts 25 cm to 0.25 m. Multiplies frequency by wavelength to get speed.
A2 (b) · 1 mark · Speed is 0.50 m/s.
Worked solution
a) Frequency = number of waves / time = 12 / 6.0 = 2 Hz
b) Wavelength = 25 cm = 0.25 m; speed = frequency × wavelength = 2 × 0.25 = 0.50 m/s