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 ?
- Length
- Tension
- 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.
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.