2 men are fishing from small boats located 36m apart. Waves pass through the water, & each man's boat bobs up & down 15 times in 75s. At a time when 1 boat is on a crest, the other 1 is in a trough, & there is 1 crest between the 2 boats.

f=15/75=.2Hz
Wavelength=36m
V=f(wavelength)=.2(36m)=7.2m/s

Is that correct? I'm most concerned about the wave length. If there's 36m between them, & one full wave between them, then wavelength must = 36m right?

Thanks for your time! :)

from reading the problem, it looks like the boats are one and a half waves apart

crest and trough, with one crest in between

I'm super confused about it because I asked my teacher how there could be 1 crest between a crest & trough

she said "There's 1 crest between them so they are further apart"
So I clarified that "that means there's 1 crest & 1 trough between? thanks" & she just said you're welcome...

boat on crest

... half wavelength
trough
... half wavelength
crest between boats
... half wavelength
boat in trough

the crest between the boats is the max of the wave that the 2nd boat is in the min of (trough)

that is a half wavelength

from the crest between to the crest the 1st boat is on is a full wavelength

the boats are one and a half wavelengths apart

Yes, your calculation for the frequency is correct. The frequency can be calculated by dividing the number of times the boats bob up and down (15) by the time it takes (75s). In this case, the frequency is 0.2 Hz.

However, your calculation for the wavelength is not correct. The wavelength is the distance between two consecutive crests or troughs of a wave. Since there is one full wave between the two boats, the distance should not be equal to the distance between the boats (36m).

To calculate the wavelength, you need to divide the speed of the wave (v) by the frequency (f). You correctly calculated the speed of the wave as 7.2m/s, but to calculate the wavelength, you need to divide this speed by the frequency:

Wavelength = speed / frequency
Wavelength = 7.2m/s / 0.2Hz
Wavelength = 36m

So, the correct wavelength is 36m, which means there is one full wave between the boats.

Ok, thank you very much :)