Calculating Velocity of Fishing Boats in a Lake

[ibysaiyan]

Homework Statement

the question is:the floats of 2 men fishing in a lake from boats is 21m apart.the waves causes both boats to bob up-down 20 times/minute.A third man observes that one of his colleagues is on the crest while other is on trough,and there is a one crest distance between them?find velocity

Homework Equations

v=f(lambda)

The Attempt at a Solution

idk but would f=20 and lambda=which i can't figure out1/4 or something
help pls
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[Delphi51]

In order to use your v = f*lambda formula you need to know the wavelength, and it is not at all clear from the wording of the question. It looks like the wording has been messed up - can you check and make sure it is copied word for word? In particular, I don't understand "one crest distance" and are they saying the boats are 21 m apart or the floats are 21 m apart?

 

[ibysaiyan]

In order to use your v = f*lambda formula you need to know the wavelength, and it is not at all clear from the wording of the question. It looks like the wording has been messed up - can you check and make sure it is copied word for word? In particular, I don't understand "one crest distance" and are they saying the boats are 21 m apart or the floats are 21 m apart?

k here is the actual question format:The floats of two men fishing in a lake from boats are 21m apart.The waves causes boats to bob up and down 20 times per minute.A man in a third boat observes that when the boat of one of his colleagues is on the crest of a wave,that of the other is in a trough,and that there is one crest between them.what is Velocity.

 

[Delphi51]

Much better! The boats are 21 m apart and they are 1.5 wavelengths apart. From that you can calculate the wavelength. Careful with the units - remember the frequency is per MINUTE.