4-29-09

We started our day off with a graded Daily Question-- A sound wave is produced with a frequency of 440 Hz (the A below middle C) in air. If the wave length is 0.75 meters, what is the air's temperature? You can try this at home! If you get stuck look at page 17 #5, both questions are very similar.

The day's agenda read: Graded Daily Question Review Daily Question and page 17 Standing Waves Pre-lab

The only homework reminder is that part 3 of our roller coaster project is due Friday. One correction to take note of about the project is that the model or drawing is not due until week 4, despite what the packet says. Two graphs are need this week alongside the technical manuel. Look in the packet for guidelines on what is needed. May 8th is when everything needs to be finished and will be presented.

We pick up page 18-19, The Speed of a Wave Lab

Answers for page 16-17 1.a. 330 m/s b. 0.00303 s c. 3.07 s 2.a. 5.7 m b. 1.3 m 3. 1 m 4. 347.2 m 5. 88 degrees Celsius

A standing wave is a new kind of wave. A transverse wave is caused by interference, looks like the wave is standing still.

We went to the back of the room and made a standing wave with a slinky. There are three spots where it is not moving (where it is held and in the middle). These are called nodes and have the minimal amplitude of the wave. An antinode is the most amount of amplitude, where the troughs and crests are. Fundamental (first harmonic)-- One antinode, simplest 2nd harmonic-- 2 antinodes 3rd harmonic-- 3 antinodes etc. It's destructive at the nodes and constructive at the antinodes. We'll learn more about what that means tomorrow. We leave the class and anticipate the Pre-lab for tomorrow.

Notes on waves: