A boat at anchor is rocked by waves whose crests are `100 m` apart and whose speed is `25 m//s`. These waves reach the boat once every :

Answer

4

Explanation

Here , velocity of the waves, v = 25 m/s
Wavelength of the waves `lambda = 100 m`
(as wavelength is the distance between two consecutive crests )
`:.` The frequency of the waves is
`u = (v)/(lambda) = (25 m//s)/( 100 m) = 0 . 25 s^(-1) = 0 . 25 Hz`
As ` u= (1)/(T) :. ` Time period , ` T = (1)/(u) = (1)/( 0 . 25 s^(-1)) = 4 s `
Thus , the crests reach the boat after every 4 s