Water waves have a wavelength of 3.6cm and speed of 18cms\(^{-1 }\) in deep water. If the waves enter shallow water with wavelength of 2.0cm, calculate the speed of the waves in the shallow water.

 Water waves have a wavelength of 3.6cm and speed of 18cms\(^{-1 }\) in deep water. If the waves enter shallow water with wavelength of 2.0cm, calculate the speed of the waves in the shallow water.

A.

0.4cms\(^{-1}\)

B.

2.5cms\(^{-1}\)

C.

10.0cms\(^{-1}\)

D.

10.8cms\(^{-1}\)

Correct answer is C

Velocity = frequency x wavelength 

v = 18cm/s, wavelength = 3.6cm, then F = 5hertz

therefore, the speed of the wave in the shallow water = 5 x 2 = 10cm/s

NOTE; as a general rule, the frequency of a wave remains constant while speed and wavelength change as it travels from one medium to another.