The sinusoidal graph shown is a graph of displacement, s against time , t of a load on a spring.

O is called the equilibrium position.

From a displacement-time graph for a wave, we can obtain

i) amplitude, a ,and

ii) period, T.

From a displacement- distance graph for a wave, we can obtain

i) amplitude, a ,and

ii) wavelength, λ

The speed of a wave is determined by its wavelength, λ, and its frequency, f , according ti the equation

__V= f λ__

For a wave moving at constant speed, increasing the frequency will result in a decrease in the wavelength.

For a wave moving at constant speed, decreasing the frequency will result in an increase in the wavelength.

Work example:

What is the frequency of water waves with the wavelength of 3.0 cm and traveling at a speed of 1.5 cm/s ?

solution :

Step 1: write formula first

V= f λ

step 2 : Substitute all given info into formula

1.5 cm/s = f x 3.0 cm

Step 3:find unknown

f = 0.5 Hz

## 2 comments:

Forgive me for asking, but isn't Hz measured in m/s and not in cm/s?

Thanks.

unit of frequency, f is Hz or 1/s.

m/s or cm/s is the unit of velocity or speed.

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