A person uses a surfboard to ride every 30th wave crest towards the beach. The wave crest travels at a speed of 1.6m/s and the distance between each wave crest is 24 m. How many wave crests does the person surf in one hour?

8

Explanation:

Applying,

v = λf Equation 1

Where v = velocity/ speed of the wave, λ = wave length of the wave, f = number of waves the person surf in one seconds.

make f the subject of the equation

f = v/λ Equation 2

From the question,

Given: v = 1.6 m/s, λ = 24 m

Substitute these values into equation 2

f = 1.6/24

f = 0.0667 wave/seconds.

If,

in one seconds, the person surf a total wave crest of 0.0667

Therefore,

in one hours, he will surf a total wave crest of (0.0667×60×60) = 240 waves crest

He rides for every 30th wave crest,

Hence,

number of wave crest the person surf in one hour = 240/30 = 8

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form

snell's law

refractve index = sin incidence / sin refraction