March 24 & 25

For these two days, we didn't do very much. On March 24th, we got our tests and labs back from Mr. Vincent, who then proceeded to give us corrections for both of them [the answers for the bonus questions were radial and coridal artery, by the way.]. Also, for those who missed their lunches during the talent show, we were given a chance to get our food and eat in class, as long as we didn't make a mess.

On March 25, we spent our final day before spring break watching an episode of Mythbusters, specifically the episode where they prove whether a lead balloon was possible, and if a wave caused by TNT can be surfed successfully. For those who don't mind spoilers, the results were "confirmed" and busted" in that order, respectively. There was also a plate of chips left out for anyone wanting a snack, but it was left untouched, I believe. That is all.

The next scribe shall be keinaan94. And yes, I am aware that my scribe is late, and I apologize for that.

March 23, 2011

Okay, so we didn't really do anything serious today. We got to class, sat down, and started writing a test for our unit about 1D waves. I hope I did well, I think the class did okay. So if you missed the test, plan some time to make up for it. There was no homework so I really don't know how to drag this scribe out any longer...

Well, yeah Jackson will scribe tomorrow!
byee!~

What we did today..

Well, today we just watched a short video that described almost everything that we've been looking at regarding the springs. The video showed transverse waves, longitudinal waves, reflected waves, transmitted waves and anything else that you could think of.
After that, we played jeopardy for the rest of class and that involved prizes! Too bad we didn't win any.... The jeopardy was to help review and study before the big test tomorrow. The test format will be something like this:

Part A (12 marks)

• Multiple choice and definitions

Part B (11 marks)

• Concepts and visuals

Part C (13 marks)

• Calculations

BONUS: 1 mark
TOTAL: 36 marks possible

Too bad I didn't put this up sooner for people who wanted to see the format.. Oh well!
Good luck studying anyways!
Jenna will be the next scribe (:

March 21, 2011: Constructive and Destructive Waves

Hello fellow classmates, so for scribing late today I needed to do some intense studying since my period two (intense homework period) was spent in the gym riot/pep rally. We started the class off with Mr. Vincent giving us new notes about wave interference. He also took attendance. After attendance we went outside to see a demonstration about wave interference and reviewed the types of waves that we have already learned. First Mr. Vincent and helper used the small denser spring to knock over a Styrofoam cup, things got more interesting when bricks were put on both sides of the cup so that the single wave produced by the spring wouldn't be able to hit the cup. Mr. Vincent and helper then timed their waves so that they will collide where the cup is between the bricks to produce a larger wave that will hit the cup. This type of wave produced is called a constructive wave. We went inside to go over the notes and learned how to draw constructive and destructive waves and were assigned the last page, Appendix 1.4: Waves in One Dimension, to complete as homework. Then we went outside again with the big spring to see how destructive waves work. Mr. Vincent told the helper to try and hit the cup that was placed midway of the spring, as he tried and tried Mr. Vincent kept creating an opposite pulse that was perfectly timed to meet up with helper's wave so that the amplitude was 0 and the cup would not be hit. Then Mr. Vincent showed us what a sound wave looks like. Then we went back in class to work on homework which we will go over tomorrow. Wednesday is our test so study that formula! Alright bai guys! Next scribe shall be David.

Answers from page 13.

Here are the answers for the "physics of a wave on a string question". Hope you all had a good weekend.

Mr V

a) (1 mark)

For each complete wave cycle of the wave, a particle on the string moves a total distance of 4A where A is the amplitude of the wave.

The total distance moved by the particle is 4(2.0 mm) = 8.0 mm.

b) (1 mark)

The frequency of the wave is 2500 Hz

c) (1 mark)

The period of motion is the inverse of the frequency: 4.0 x 10^-4 s

d) (1 mark)

For each second, or one period of motion of the wave, the vertical distance travelled by the particle is 8.0 mm or 0.0080 m. To travel a distance of 1.0 km, the number of cycles of the wave (or periods of motion) is

number of cycles = 1.25 x 10⁵ cycles

e) (1 mark)

The total time required is

t = (1.25 x 10⁵ cycles)(4.0 x 10^-4 s/cycle) = 5.0 x 10¹ s

Reflection and Transmission of Pulses and Waves

We started off the class with the answers given on the whiteboard from the homework we were assigned to finish the previous day; Describing Waves Assignment #12-16 and page 13 in our handouts #1-2.

Here are the answers you can refer to in case you missed today's class:

Describing Waves
12) D
13) V = λ/T or V = λf
14) 2 m/s
15) 24.2 m
16) 5 s

*For question 16, a few of us got the answer 2 s. I do not think Mr. Vincent heard us ask about it so may you please go over it on Monday?

Page 13
1) 5.2 x 10² m
2) 1.7 x 10^-5 s

We then moved onto Wave Reflections and Wave Transmissions where we experimented with two types of springs; a light medium spring and a heavy medium spring.

We all went in the hallway and watched the reflection pulse of the light medium and heavy medium spring. We learned that when we gave the spring a wave, once the pulse reached the barrier, the rope exerted a force upward on the support. This support then exerted an equal but opposite force downward on the rope. This downward force on the rope is what causes the pulse to reflect back on the opposite side, or inverted. This can be related to Newton's Third Law where; every action has an equal and opposite reaction.

From a free end of a spring, meaning there is no solid barrier at the end, once the pulse reaches the end of the spring, the particles exert an upward pull on the end of the rope which generates a reflected pulse that is now on the same side of the rope as the incoming pulse.

A reflection can be defined as the return of a pulse or wave from the boundary of a medium.

Next was Wave Transmission in Two Media, where we taped together the two different springs. We then tested out what happens to the waves as the two are taped together. We learned that when a wave passes from a fast medium into a slow medium, the particles in the slower medium have greater inertia. The reflected wave is inverted where the transmitted wave is not inverted.

A partial reflection is when a wave moves from one medium to another, some reflection occurs at the boundary between the two media, where some of the energy is transmitted into the new medium and some is reflected back into the original medium.

We then went back to class and drew diagrams of these different types of waves we saw because by the end of this lesson, we should be able to draw transmission and partial reflection of pulses and describe how pulses or waves in one dimension are reflected from a fixed end and a free end. I will attach photos of how the diagrams look like somewhere on this post since I cannot move the image..

There was a remaining 20 minutes of class when we received our next few pages of notes, pages #17-26. These pages should explain everything about the Reflection and Transmission of Pulses and Waves that we learned today.

For homework, we were assigned to finish any questions given in the pages #17-26. This is suppose to help us review for the test we have on Wednesday!

Last but not least, 7evin shall be the scribe for Monday's class. I hope this did not bore any of you..just wanted to cover everything! Have a great weekend.

Dynamics Test Answers