Calculating frequency and wavelength off of a graph

[Havenater23]

Homework Statement

http://i213.photobucket.com/albums/cc285/havenater23/RIP.jpg?t=1301441030

I've been trying out things on this problem, I really need some help. I tried finding the frequency by counting the waves and dividing it by the seconds it takes through the waves. EX : 4 (Waves)/ 11.2 (Secs). Then after that using the period to find frequency, then with the solved for I can find the wavelength. I don't know if I am right though, please help
-Thanks

Homework Equations

The Attempt at a Solution

 

[Redbelly98]

Homework Statement

http://i213.photobucket.com/albums/cc285/havenater23/RIP.jpg?t=1301441030

I've been trying out things on this problem, I really need some help. I tried finding the frequency by counting the waves and dividing it by the seconds it takes through the waves. EX : 4 (Waves)/ 11.2 (Secs). Then after that using the period to find frequency, then with the solved for I can find the wavelength. I don't know if I am right though, please help
-Thanks

On that graph, 4 "waves" (or full periods) takes about 10 seconds. Dividing 4 by that time will give you frequency, as you said.

After you get frequency, I don't know if you are doing it correctly unless you show your calculations.

 

[Havenater23]

Okay, well if you take 4/10 you get like 0.4 hz then.
Since you know the velocity = 12 m/s and you know the frequency then you can find the wavelength. The only thing is , you get an answer of like 30 m. If you look at that graph I find that almost impossible to correspond.

 

[SammyS]

Okay, well if you take 4/10 you get like 0.4 hz then.
Since you know the velocity = 12 m/s and you know the frequency then you can find the wavelength. The only thing is , you get an answer of like 30 m. If you look at that graph I find that almost impossible to correspond.

Why?

The graph is at a single location.

The wave velocity is 12m/s., so in a time of 10 seconds, a wave travels 120 meters.

The graph tells you that 4 waves pass by in a time of 10 seconds.

Put those together, and 4 waves span a distance of 120 meters.