(a) The frequency of water wave is 2 Hz.
(b) The wave speed of the water wave is 3.6 m/s.
<u>Explanation:</u>
(a) It is known that completion of one complete wave in 1 second is defined as frequency of 1 HZ. So here there are 120 waves crossing the boat in 1 minute. So the frequency of the water wave will be
As the time is 1 minute which is equal to 60 seconds and the number of waves is given as 120 then the frequency of the water wave is
So the frequency of water wave is 2 Hz.
(b) Then if the wavelength of the water wave is 1.8 m with a frequency of 2 Hz, then speed of the wave can be determined as the product of wavelength with frequency.
So Speed = Frequency × Wavelength
Speed = 2 × 1.8 = 3.6 m/s.
So the speed of the water wave is 3.6 m/s.