You are in a row boat on a lake and a speeding boat passes you. your boat starts to bob up and down.?

Question

you observe that you bob every 0.5secs, and the waves are 2.5m apart. what is the wave speed?

Answer 1

5m per second

Answer 2

You are bobbing every .5 seconds, so your frequency is 1 / 0.5 = 2 per second.

The wavelength is 2.5 meters, since you can see that the crests are 2.5 meters apart, and you can determine the wavelength by measuring the distance from any point on a wave to the same point on the next wave.

Now the speed of the wave equals

the frequency times the wavelength,

hence 2 x 2.5 = 5 meters per second.

OK?