# Speed of transverse waves

1. Jun 29, 2014

### desmond iking

1. The problem statement, all variables and given/known data

my working is as in the photo which is v=f X wavelength = 0.4 X 0.04= 0.16 ... but the ans given is 0.10m/s
2. Relevant equations

3. The attempt at a solution

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Last edited: Jun 29, 2014
2. Jun 29, 2014

### BvU

Ever look at the dimension of speed and compared to the dimension of your answer ?

Oh, and use the template, please. If you'd done so you would have discovered where you went off the rails. (And never have posted in the first place, thus robbing me of a chance to promote the use of the template. All bad things have a bright side ).

If you have time left, read the guidelines too....

3. Jun 29, 2014

### dauto

The value you got for the frequency f is not correct.

Also 0.4 * 0.04 = 0.16 isn't a correct equation.

4. Jun 29, 2014

### desmond iking

sorry... my working should be ( (40X10^-3 )X (4X10^-3) )/100= 0.016 m/s .. which part is wrong?

5. Jun 29, 2014

Your second diagram is not clear. Distance in what?

6. Jun 29, 2014

### desmond iking

Ignore the question. Found my mistake.

7. Jun 29, 2014

### BvU

How about betting on mm ?

But poor Des is still looking at the wrong frequency. He may be confused by the label on the x-axis of graph a.

Des: you see there one full period ends at the number 40. that is the period divided by ms.

Meaning: ${period \over ms} = 40\,$ so that period = ??
What is the dimension of frequency ?
- - - -

Graph b x-axis label is distance / mm but there he has no problem extracting $\lambda$ = 4 mm.

Des: Now, do you see where you ended up upside down ?

- - - -

Personally I think the labels are quite correct, but in my own work I use labels like "Displacement in cm" and "Time in ms" that (I hope) are less confusing than the correct labels.

(But then, I am not a teacher / pedagogics expert. Any opinions/experience from the field?)

 woke up after some soccer. Des is happy. My opinions question stands.