Wave speed and frequency

What is wave speed?

It is the distance in metres travelled by a wave in 1 sec.

The speed at which a wave travels depends upon the medium it is travelling through.

What is the unit and symbol for wave speed?

V, m/s

What is the unit and symbol for wavelength?

A, m
A = v/f

What is frequency?

Frequency is the number of waves that pass a point per second.

period time can be worked out by T= 1/f

What is the unit and symbol for frequency?

F, Hertz (Hz)
F = V/A

How do you work out frequency on a graph?

Count how many full waves before a second.

How are different notes/pitches created on string instruments?

Different noted are created when different speed waves are created by playing the strings

What does thicker strings mean?

- Thicker strings give a slower speed wave and so produce a lower sounding notes.

(Higher mass per unit length)

What does tighter strings mean?

- Tighter string with more tension, give a faster speed wave
- So produce a higher sounding note.

What does the equation for wave speed link?

Links the mass per unit length of string with the tension of the string.

To increase speed length what happens?

increase the tension
thinner string
shorter length

To decrease speed length what happens?

decrease the tension
thicker string
longer length

What does the loudness of the note depend on?

The harder the string is plucked
The bigger the displacement
So the bigger the amplitude
And louder the note
(4marks)

What is the equation for the speed of a transverse wave in a string?

V = √t/u

v = velocity/speed (m/s)
T = tension (N)
u = mass per unit length (m/L, kg/m)

How do you convert kg to g?

Kg → g = x1000
g → kg = /1000

How do you convert m , cm ,mm?

m → cm (x100) cm → mm (x10)
mm → cm (/10) cm → m (/100)

What's the equation for tension?

T = v² x u

What's the equation for mass per unit length?

u = T/V²

What does a lower note mean?

slower speed.

What are the steps to work out v = √t/u?

1) Convert the number in the question to the correct units.
2) Calc mass per unit length = m/L
3) Calc wave speed