Wed, Jan 30, 2008 - 4B

Hand out new Tiger Passes
Hand out notebooks - write name on cover, on inside cover write the addresses of the course blog sites, write down phone numbers of friends to contact in case of absence.
Go over final exam

Two ways to transmit energy: matter can carry energy (I can throw something at you to get your attention) or waves can carry energy (I can shout, "Hey!"). In the second case, the matter did not actually travel from me to you, only the wave disturbance in the matter moved. Energy moves in waves.

For sound waves, I speak and cause air molecules to wiggle. They hit other air molecules causing them to wiggle. This goes on until the air molecules hit your ear drums causing them to wiggle and you hear sound. If there is no air to wiggle, as in outer space, sound can't travel. Movie "Alien" - in space no one can hear you scream.

A vibration is a wiggle in time. A wave is a wiggle in time and space. Demonstrate with picture on whiteboard. Move hand up and down (vibration) then also move to side (draw wave)

Demonstrate that sound waves are caused by vibrations. Hit tuning fork, hear sound. Put ringing tuning fork in front of computer screen and see strobe effect of vibration - belly dancing tuning fork.

Two types of waves, transverse (movement of particles is perpendicular to direction of wave) and longitudinal (movement of particles is a-long the direction of the the wave). Demonstrate both with a slinky. Demonstrate transverse wave by students doing stadium wave.

Demonstrate with slinky and pictures: wavelength, frequency, energy, amplitude, peak, trough
High frequency = high energy = short wavelength (with visible light, this is violet light)
Purple tie days are high energy days.
Low frequency = long lazy wavelength = low energy (with visible light this is red light)

For sound, long wavelength = low frequency = low pitch
For sound, short wavelength = high frequency = high pitch
Demonstrate with frequency generator, oscilloscope, and speaker

Students updated notebooks for daily activities.

Handed out Reading Assignment 11.1 - due Friday, Feb 1, 2008