Waves Homework help -- Waves on a String

[Riemannenthusiast]

Homework Statement

I attached an image

Relevant Equations

lamba*frequency=wave speed
1/f=speed

Okay well I'm stuck on this one. I know that lamba times frequency is wave speed and 1/f is period. I think that the wavelength of the wave is four but what is the frequency? (1/2)? Would I multiply 4*1/2 to get 2 m/s as the wave speed and then if the frequency doubles to .25, the wavelength be 8m? I think I am missing something because I don't think that's the proper way to find the frequency. Is there something special about the string?

 

[PeroK]

The "Homework Statement" is where you tell us the question or problem. Rather than have us take a wild guess at what you're trying to do!

 

[Cutter Ketch]

A homework statement is the problem statement: the question the way it was asked of you. It is extremely helpful in introducing us to the problem so we know what you are talking about. As it is, I can not make heads nor tails out of your question.

 

[Riemannenthusiast]

The "Homework Statement" is where you tell us the question or problem. Rather than have us take a wild guess at what you're trying to do!

Oh okay, thank you!

 

[Riemannenthusiast]

A homework statement is the problem statement: the question the way it was asked of you. It is extremely helpful in introducing us to the problem so we know what you are talking about. As it is, I can not make heads nor tails out of your question.

Gotcha. I attached a picture of the question :)

 

[Cutter Ketch]

Hmmm ... I can see why you are stuck. Is this the whole problem? Was there some prior related statement about the string in this problem?

 

[Riemannenthusiast]

Hmmm ... I can see why you are stuck. Is this the whole problem? Was there some prior related statement about the string in this problem?

I took a screenshot of the answer choices...will that help?

 

[phinds]

the wavelength of the wave is four

You might want to rethink that. Also, you should not state wavelength without units.

 

[Cutter Ketch]

I see that it expects numeric answers, not just relative comparisons.

The problem is very clear what is plotted. The string is stretched horizontally. The transverse wave propagates horizontally. The graph shows the vertical (i.e. transverse) displacement of a single point on the string as a function of time. From this one can only derive the frequency and the amplitude. I do not believe it is possible to relate these to the speed or wavelength without additional information. The problem is flawed.

 

[Riemannenthusiast]

Do you think that I could do distance over time to find wave speed. Like the wave traveled 4 meters in 2 seconds so its speed is 2 m/s and then if the frequency doubles from .5 to 1, the period is one and the wavelength would be 2m?

 

[Cutter Ketch]

Do you think that I could do distance over time to find wave speed. Like the wave traveled 4 meters in 2 seconds so its speed is 2 m/s and then if the frequency doubles from .5 to 1, the period is one and the wavelength would be 2m?

What makes you think the wave traveled 4 m in 2 s? That information is not given in the problem statement nor can it be derived from the graph.