12.19.2007

Hello! This is Mary Ann

I wasn't able to scribe for yesterday's class since I was away. Noonie will have that post up hopefully sometime tonight.

Today we did a lab on Acceleration Due to Gravity. We took a rubber door stopper and had it tied to a string. We then allowed it to swing for 20 cycles while the string was 120cm long. While doing this, we recorded the length of time it took for the door stopper to reach 20 cycles.
We noticed, through this lab, that when the string was shortened, the faster it took the stopper to reach 20 cycles.
There were also some questions that accompanied the lab.

That was basically all that we did today.

The next scribe will be KRISTINA!!!!!!!!

Kinematics

On Friday we went over the fill in the blanks sheet, Chapter 3 study guide. Here are the answers if you happened to miss any.

Position and Distance
-position
-frame of
-frame of
-magnitude
-scalar
-magnitude
-direction
-vector

Average Velocity
-instantaneous
-position
-vector
-displacement
-time
-v=Δd/Δt
-Δd
-distance
-Δt
-time
-distance
-time
-conversion

Finding Displacement from Velocity and Time
-Δd=(v)(Δt)
-v
-Δt
-time intervals
-uniform
-v=Δd/Δt

Position-Time Graphs
-position
-time
-straight
-linear

The Slope of a Position-Time Graph
-vertical
-horizontal
-vertical
-horizontal
-rise
-run
-velocity

Also, page 3.6 was to be done for Friday's class. If you didn't hand it in yet, please do so for Monday.

The next scribe is Edward!

Waves Moving From One Depth to Another & Refractions

Hello! This is Mary Ann.

In class today, we got our assignments and test back. We went over the answers for the test, so if you missed any of them..here they are!

1.


This is a transverse wave.


2. amplitude = 1.5 cm
wavelength = 4.5 cm


3. a. longitudinal
b. (i) compression
(ii) rarefaction
(iii) wavelength


4. a. f = 50/10 = 5Hz
b. T = 1/5 = 0.2s


5.
The wave should appear inverted since it hits a fixed end.

6. This is how your diagrams should have turned out.

7.


8.

9. Constructive Interference: occurs when two pulses on the same side pass through each other. This causes the amplitude to increase.
Destructive Interference: occurs when two pulses on opposite sides cancel when overlapped.

10. The main function of a wave is to transfer energy through a medium.

11. a) true
b) meters or cm
c) true
d) normal
e) transverse

12. A standing wave consists of two waves of equal amplitude, frequency and wavelength.

The red dots represent the nodes. The blue dots represent the anti nodes.

After making corrections on the test, we looked into the green booklet on page 9-11 and learned about Waves Moving From One Depth to Another & REFRACTIONS.

When waves move from one depth to another, the frequency does not change. What changes is the speed of the waves. In deep water, the speed of the waves is vdeep = (fdeep)(λdeep). The speed of the waves in shallow water is vshallow = (fshallow)(λshallow). Since the two frequencies are the same it can also be written as vdeep/vshallow = λdeep/λshallow.

In this picture it shows a straw in a glass of water that appears to be broken but it is actually being refracted since half of it is in water and the other in air. Air and water are the two mediums in this case.

*NOTE*
-The 5 questions on Waves in Two Dimensions - Assignment 1 is due tomorrow.
-Our project is due on Tuesday, September 25th.

The next scribe is going to be LAURESSA.