# Vibrations in strings and pipes

Standing Wave

http://www.walter-fendt.de/ph14e/stwaverefl.htm

Elastic Band Band!!

Stretch an elastic as far as it can, by taking it opposite ends pull hard, twang, listen and describe

Shorten the length and pull as hard as you did in the previous attempt, twang listen, describe and compare

Go back to the original length and pull but not so hard twang listen, describe and compare

Shorten and again pull but not so hard twang listen, describe and compare

What factor affect the frequency of the sound from a string ?

1. Length
2. Tension
3. String Variables (thickness, density(mass per unit length))

↑ length → ↓ frequency (inversly proportional)

↑Tension → ↑ frequency (directly proportional)

Pipes

How do Blind people make tea?

Well without spilling hot water all over the kitchen.

They use a spoon.

Everybody uses a spoon, but its how they use a spoon.

Demonstration

Blindfold a student, using a jug of COLD water ask them to fill a glass close to the brim give them a spoon to use.

Can you make music from different vessels with different amounts of water in them?

pythagoras discovered the harmonics as he walked by a metal forger

Stationary waves in strings and pipes.

Standing wave!

http://www.walter-fendt.de/ph14e/stwaverefl.htm

open pipe standing wave

http://www.walter-fendt.de/ph14e/stlwaves.htm

Relationship between frequency and length.

http://www.acoustics.salford.ac.uk/schools/index1.htm

Harmonics in strings and pipes.

f = 1 T 2l μ for a stretched string.

You can use tuning forks and a sonometer.Make sure the string is at a reasonable tension.Put the paper rider as a cylindrical shape,and have it small.Strike the tuning forks and put them against one of the bridges

There are many different online generators, I wanted one that was variable.

http://www.wavtones.com/functiongenerator.php

Appropriate calculations.

pg 202 Real World Physics

Q2

Use string and wind instruments, e.g. guitar, tin whistle.

String section and woodwind section in orchestras.