A wave train of a plane wave with wavelength 1.8 cm, travels from deep water into a shall water. Then the velocity of waves on surface shallow water, if its wavelength in shallow wave is 1 cm, is (The velocity of waves in surface deep water is 36 cm/s)

Options

A. 35 cm/s
B. 20 cm/s
C. 64.8 cm/s
D. 37.4 cm/s

Answer

B

Explanation

`(v_(s))/(v_(d)) = (lamda_(s))/(lamda_(d)) = (1)/(1.8)`
`v_(s) = (v_(d))/(1.8) = (36)/(1.8) = (360)/(1.8) = 20 cm//s`