# Homework Help: Harmonic wave

1. Dec 13, 2005

### physics_ash82

ok I need help starting this problem. I always have trouble seeing which formula to use so ant thoughts would be helpful

A harmonic wave is traveling along a rope. It is observed that the oscillator that generates the wave completes 40.0 vibrations in 30.0 s. Also, a given maximum travels 425 cm along the rope in 10.0 s. What is the wavelength?

2. Dec 13, 2005

### Galileo

This gives you the frequency.

This gives you the speed of propagation.

You know frequency and speed and you need wavelength. Do you know any formula relating these quantities?

3. Dec 13, 2005

### physics_ash82

so I would use the formula a=Aw^2cos(wt)

4. Dec 14, 2005

### Galileo

No. You'd use a formula relating the frequency, speed and wavelength of a traveling harmonic wave.

5. Dec 15, 2005

### Omar.Castillo

Ok I hate seeing people trouble through homework
especially if your name is ashley (personal joke)

Anyway the formula you need is pretty simple and straightforward

speed= wavelenght * frequency

I dont quite know how to place greek letters in this forum but thats basically it.

you should know how to get the speed which is simply distance/time
and the frequency should be obtained by the number of vibrations per second.

Just solve for lambda err wavelenght and plug in numbers :D