## anonymous one year ago If 20 waves of water pass you in 5.0 s and the waves are 2.0 m long, how fast are they moving? 1.0 m/s , 2.0 m/s , 4.0 m/s , or 5.0 m/s ?

1. Michele_Laino

is 2.0 meters the wave length ?

2. anonymous

i think so :)

3. anonymous

ohh so our solution is 2.0 m/s?

4. Michele_Laino

I'm pondering...

5. anonymous

ok!

6. Michele_Laino

if 20 waves pass in 5 seconds, the one wave pass in 5/20=0.25 seconds

7. Michele_Laino

so I see one wave length every 0.25 seconds, and the requested speed is: 2/0.25=8

8. Michele_Laino

what is wrong in my reasoning?

9. anonymous

ohh okay! ermm i am not sure... :/ the solution is 8 though right? :/

10. anonymous

i am not sure why that is not a choice? :/

11. anonymous

because your reasoning makes sense :/

12. Michele_Laino

yes!

13. anonymous

okay! thank you!! :)

14. Michele_Laino

I'm sorry!

15. anonymous

haha it is okay! thank you:)

16. Michele_Laino

please try to ask to another tutor

17. anonymous

okie:)

18. anonymous

thankyou!!

19. Michele_Laino

please wait I call for another tutor

20. anonymous

okie! :)

21. Michele_Laino

22. Michele_Laino

23. Michele_Laino

24. Michele_Laino

25. Michele_Laino

26. Michele_Laino

27. ParthKohli

$v = f \times \lambda$

28. ParthKohli

v - velocity of the wave. f - frequency of the wave (number of waves passing in 1 second). $$\lambda$$ - wavelength, or length of a wave.

29. anonymous

so f=20/5 = 4 waves per second? and wavelength is 2.0 m ?

30. ParthKohli

That is correct. The answer is thus $$4 ~s^{-1} \times 2 ~m = 8 ~ms^{-1}$$.

31. anonymous

ooh okay! hmm i am not sure then :/ i was not given that choice :( i think maybe a typo? haha :P but yes, thank you both very much!!:)

32. Michele_Laino

thanks! @ParthKohli