March 26, 2009.

Hi!

Today, we corrected the chapter 10 study guide and the problem 1-6 on page 330 ( duck book)

Answers (chapter 10 study guide)
Work:
force, distance, direction, w= Fd, work, force, distance, scalar, joule, newton, meter, joule,moves, force displacement.

Work and direction of force:
in the direction of, perpendicular, in the direction of, cosine,direction of motion, negative, energy, energy, motion,positive,negative.

Power:
rate, rate, energy, P=W/t, power, work, time, watt, joule,one second, kilowatt.

Answer (problem 1-6 on page 330 duck book)
1a. w= Fd (d=15cm. F= 40N)
= 40N x 0.15m
=6 N/m or 6 J.
1b. W= Fd (m= 50 kg, d=1.95m, g=9.8)
=mgd
=50kg x 9.8N/kg x 1.95m=956 J
1c. W= Fdcos25o
=120N x 4m x cos25o
=435J
2. W= Fd (a=2.5m/S2, V2= 12.5m/s, t=5s, F=5000N)

V1= V2 - at=12.5m/s - ( 2.5 m/S2 x 5s)
= 0

d=( V1+V2)/2 x t
= (0+12.5m/s)/2 x 5s
=31.25m

W= Fd
= 5000N x 31.25m
= 156250J or 1.6 x 10^5 J

3. (F= 78N , m = 10m)
angle = 90 - 35 = 550

W= Fdcos550
= 78N x 10m x cos550
= 447.4 J

4.( V1= 25 m/s, V2= 14m/s, t= 5s, m= 52000kg)

d= (V1+V2)/2 x t
= (25 + 14)/2 x 5= 97.5m

a= (V2- V1)/t
= (14 - 25)/5
= -2.2 m/S2

F=ma
= 52000 x (-2.2m/S2)
= -114400N

W= Fd
= 114400 x 97.5
= 1154000J

5a. w= Fd
= 175 x 55
= 9625 J

5b. W= A1 + A2 + A3
= (xy/2) + (xy/2) + xy
= [ (0.04 x (-20))/2] + [ (0.04 x 20)/2] + [(0.12-0.08) x 20]
= (-0.4J) + (0.4J) + (0.8J)
= 0.8J

6. ( W= 480 J, m=3 kg, g= 9.8)
W= mgd

d= W/ mg
= 480J/ 3 x 9.8
=16.3m


Today, Ms. K gave us some worksheet to work onChapter 11 study guideWorksheets on chapter 10 and 11 study guide.

The next scribe is Abbas.
Bye!

March 25, 2009

Hello... Everybody. I do today's scribe. By the way, my name is Hao.G . hahaaaa

Today we talked something about WORK AND ENERGY.

We define kinetic energy, gravitational potential energy, and the potential energy stored in a compressed or stretched spring. If all forces are conservative, the mechanical energy of an isolated system is constant. If non-conservative forces are present, we use the work-energy theorem to equate the work done by the non-conservative forces and the change in mechanical energy. (http://theory.uwinnipeg.ca/physics/work/index.html)

we handed in a lot of stuffs like:
1) Centripetal Acceleration & Force assignment
2) Test w/ correction
3) Lab about centripetal force
Thank you Mary I copy your blog. I think somebody didn't done it, so post it again.

what we need to do today is
1)READ PAGE 101 （the green book)
2)READ UP PAGE 323-330 (DUCK BOOK)
3)DO PROBLEMS PAGE 330 1--6 (DUCK BOOK)

If you didn't take the book to home, that 's OK . I post the questions for you guys.





1. Determine the work done in each of the following cases:
a) Kicking a soccer ball forward with a force of 40N over a distance of 15 cm
b) Lifting a 50-kg barbell straight up 1.95m
c) Pulling a sled with a force of 120N at an angle of 25 degrees to the horizontal if the sled
is displaced 4.0m forward




2. A tow truck pulls a 3000-kg car form rest with a horizontal force of 5000N. The truck and
car accelerate at 2.5m/s^2 for 5.0s to reach the speed limit of 45 km/h. How much work
is done by the tow truck?




3. A wheelbarrow is pushed by a force of 78N [U 35 degrees R] over a distance of 10m. Determine the work done to move the wheelbarrow along the ground.




4. A 52,000-kg train slows form 25m/s to 14m/s in 5.0s. Calculate the work done on the train.




5. Calculate the work done in each of the following graphs

6. Determine the height form which a 3-kg axe must be dropped so that it does 480J of work to split a log resting on the ground.



In the final, I want to show you guys some videos, but I don't know how to do it. I just give you the address.

http://www.youtube.com/watch?v=2WS1sG9fhOk&feature=related




next one is Tan LM.
see you guys tomorrow

March 24, 2009

anyongheseo,,

Whew! What am I going to say? Hmm,,, what did we do today? Well, we handed in a lot of stuffs like:

1) Centripetal Acceleration & Force assignment
2) Test w/ correction
3) Lab about centripetal force (remember the lab that we did yesterday using super duper hi-tech equipments such as string, washer, rubber stopper and a timer?) ^^,

Also, Ms. K gave us some sheets to work on...

Basically, that’s it...

I guess half of the class (including me) spent their time working on the lab sheet and assignment. So there’s nothing much to say... (I’m sorry I wish I could share some more but that’s all I can remember...^^)

And oh, if I’m not mistaken, we don’t have period 5 & 6 tomorrow, right? Yaaaiiiyyeee!!! ^^,

Next scribe… Hao Gao…^^, Aja Aja Hwayting (fighting)

Centripetal Force Lab.

hello everyone!!

ahmm,,, today in class we got our catapult project back then we did a centripetal force lab. and it was fun :)Then, finally here's what we have to find during the lab.



Also,....
That's all we did for today's class
ahmm,, for this lab. I don't know when is it due but try to finish it..

Reminder:
Centripetal Acceleration and Centripetal Force are due tomorrow...

next scribe is pretty Mary =)

March 20,Centripetal Force

Hi!
Today's Class

We went over the "practice problem" pages 152-153 questions 13-16


Ms.K gave us the CENTRIPETAL FORCE worksheet (it is due on Tuesday)


Answers:(problems 13-16)

13. It takes a 615 kg racing car 14.3 s to travel at a uniform speed around a circular racetrack
of 50.0 m radius.
a.What is the acceleration of the car?




b. What average force must the track exert on the tires to produce this acceleration?



14. An athlete whirls a 7.00kg hammer tied to the end of a 1.3 m chain in a horizontal circle .The hammer
moves at the rate of 1.0 r/s.


a.What is the centripetal acceleration of the hammer?




b.What is the tension in the chain?




15. Sue whirls a yo-yo in a horizontal circle.The yo-yo has a mass of 0.20kg and is attached to a string 0.80
long.
a.If the yo-yo makes 1.0 complete revolution each second ,what force does the string exert.



b. If Sue increases the speed of the yo-yo to 2.0 revolutions per second ,What force does the
string exert on it?



16. A coin is placed on a stereo record revolving at 33 1/3 revolution per minute.

a.In what direction is the acceleration of the coin ,if any?
Ans. Inward

b.Find the acceleration of the coin if any ,when it is placed 5.0,10.0,15.0 cm from the center of
of the record.
Ans. 5.0 cm-------0.609 m/s2
10.0 cm -----1.218 m/s2
15.0 cm----- 1 .28 m/s2


c.What force accelerate the coin?

Ans.Friction


d.At which of the three radii listed in b would the coin be most likely to fly?

Ans. 15.0 cm

So, thats all for today's class.....(=*.*=)....the next scribe will be ramina..:>

03.19.09 CIRCULAR MOTION

I'll make this short...

Today, we corrected the following sheets:
1. Chap 7 Study Guide: 7.2 Periodic Motion
2. Free-body Exercise: Circular Motion

And Ms. K was nice enough to post the answers (below) to save me some time. Aha.

And then...

We watched a video about circular motion. It's too bad it's not the "same-same" guy. =(
And uhh, I wrote some notes down (and some copied from Aldrin o.o) but unfortunately, I kind of couldn't understand my notes so I think it's best if you visit this site... it's very useful: http://en.wikipedia.org/wiki/Circular_motion

Moreover, Ms. K gave us (or more like, we had to get it ourselves) the following sheets:
Ichi: 5.11 Frames of Reference
Ni: 13.4 Centripetal and Centrifugal Forces

Lastly, she told us to do some "practice problems" on pages 145-146, questions 9-12 and on pages 152-153 questions 13-16.

And that's about it...
Uhh.. have fun... in everything you do. lol?

The next scribe will be KIM C.

Circular Motion Freebody Diagrams

Circularfbd

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Wednesday, March something, 2009

Kay so like, today there was like, no substitute for once (hooray...) and then like at the beginning of class, something happened, I forgot what it was. But then yeah, after, errybody sat down and stuff and mrs. teacher dude was like, swinging this ball on a rope saying she was gonna smash some kid with it. anyway, it turns out that, when she was like spinning the ball in her hand thingy, umm..... tension.... force.... ball... inwards... put it together however you like. =]
And for the exam come june, the answer is ''straight'' rather than ''in a circle''.
Okaaaay
So then after that, we got 3 sheets, a yellow one, and two white ones, I think.
The yellow one, was a word search, and I copied off Ryan and Tam. The word search had something to do with centrifiguloponular force. And then the other two sheets were, stuff that you need to do later on whenever. AAAAAAAAAAAAANd theeeeeeeeeeeen we got our tests back (hooray...)
And I beat Ryan's score by 10, so I'm happily ever after (Not good english).
And theeeeeeeeeeeeeeeeeeeeeen
Ummm
After that, weeeeeeeeeee......... uhhh
Oh yeah, Thamie was in the class. And then after that, we put our chairs up, and then the bell rung.
And then after the bell rung, we lefted the classroom and was finished.
That's all I can remember.

Scribe for tomorrow will be zhette!!!

More Work with Projectile Motion

Hello, Kristina here with today's scribe. Gee, it has been a long time since I did a physics scribe post O_O..

Anyways, at the beginning of class Ms. K gave out the Projectile Motion sheets from yesterday to those who weren't at class that day. Then she gave us a new worksheet titled, "The Trajectory of a Projectile". We were given 10 minutes to work on it and then we went over the answers.

Here they are:

1) trajectory
2) projectiles
3) horizontal and vertical velocity
4) stays constant
5) increases
6) they don't affect each other
7) gravity
8) no forces act upon the drops; Newton's 1^st Law
9) V_x: stays constant, no force acted on; V_y: gravity acts upon droplet so velocity increases
10) yes, force of gravity would be acting on a larger mass


After we went over the worksheet, we were given another review sheet since our test is apparently on Monday. Only do up to question 4 since those are the projectile motion questions. Make sure you finish them since I believe we might be going over the sheet from yesterday and today's worksheet tomorrow in class.

Ms. K also wanted to note that we should know how to draw an object just being dropped and an object being thrown. Note that the dropped object only has vertical velocity, while a thrown object has a horizontal and vertical velocity. Remember that the horizontal velocity is always constant and doesn't affect the vertical velocity at all!


Ehh...and it looks like I was supposed to scribe for yesterday's class? Although I do remember seeing Darryl choose someone else....so...ah whatever. I'll include yesterday's class too.

So basically, we had a sub yesterday and he made us finish up the Chapter 7 Study Guide since no one had finished it the day before. We then went over the answers after having been given about 30 minutes of class time.

Here are the answers in order:

trajectory, constant, constant, zero, acceleration, force of gravity, equal to, viewpoints, horizontal, horizontal, vertical, trajectory, horizontal, vertical

zero, -9.8 m/s², zero, increases, stays constant

positive, zero, negative, the same, reversed, horizontal, horizontal, vertical, equal, equal


Then after going over the answers the sub went over the sheet titled, "Tossed Ball". Again, I shall post the answers...

Answers:

Horizontal velocity stays constant so the answer for the horizontal ones will be 5 m/s throughout.
Vertical velocities (Starting from the left side): 20, 10, 0, -11.2, -21.2, -30.4

After going over those answers, we were ready to move onto another worksheet, the Projectile Motion one I talked about earlier in this scribe.


Yep, that's all that happened on the past two days. Remember that there is a test on Monday and that catapults are due on Tuesday. The next scribe is Pacifico. Have a happy Pi Approximation Day tomorrow everyone! That is all.

March 10, 2009: Projectile Motion

Hey this is Darryl L.

In Today's Physics class we started off by listening to another Physics music called "Harry the Human Cannonball". Its another one of those songs that explains this time projectile is used as a theme for the story being told. Using physics a man calculates his trajectory aiming himself to intersect a lady on a trapeze as she falls in a net. There he aims and fires out of a cannon and in mid air catches the lady and lands in the net.

Next we did another lab involving 2 pennies and a ruler:

Step1: with 2 pennies place near the edge of the desk at a little distance apart from one another and the ruler placed behind them. You must push both of the pennies at the same time with the ruler and pay close attention to where the pennies land and the sound they make. Do this trial again but with different amount of force pushed on the pennies and again pay attention to where they landed and the sound they made.

Step 2: place both pennies again near the edge of the table. This time using the ruler at one end is placed near the edge of the desk and held down. Using the other side of the ruler you must push the pennies off the table. Repeat the steps using different amount of forces and keep track of where it landed and the sound they made.

You will notice that slide one is a diagram to show the motion of the pennies that were moved in step 2.

Slide 2 are formulas derived from the very first formula in green that can be used to help with projectile motion problems

On the Final slide is a diagram showing the time it takes for a projectile to reach its maximum height and which it equals the same amount of time for it to fall back down.

One last thing, we received another project involving us to build a catapult! A small catapult able to launch a ping pong ball across from one table to another (which if i heard right is about 80 cm). This project is due 7 days from today and is judged by the accuracy of the catapult and not by how far it can shoot the ping pong ball.

Well that's mostly what we did today in physics, if anyone else has something to add leave a comment and ill try to add or fix if anything is wrong or missing.

The next scribe i choose is kristina, good luck.

D-S skyline out.

Projectile Motion

Projectile Motion

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Niwatori-san's *sigh* corner...

O hayao gozaimasu... *sighs*

Niwatori-san with his update with what we did yesterday in Ms.Kozoriz's Physics 40S class (note that im trying to get as much wording in as this post isn't going to be that long
-____-)


Well we for the start of the Monday class we once again were just going to finish our lab and -quoting MOOffatt's post from yesterday- we were to finish up the study guides and the worksheet we were given out that day once done the lab.

With some progress going on...

Seems like our class hasn't quite finished the labs yet being the majority of us -___-.

ANYWHO... the next task in class will be shown on the following day.
(yes, pretty progressive change in course yes?)

Well as always Gambete mina! And good luck in the future.

Next scribe poster is D-S Skyline!

^^ have a nice day!

Momentum Problems

Momentum Problems

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March 6, 2009

Hey guys its Ryan.M, all we did in class on Friday was a momentum lab.

1. First we grabbed 2 marbles, a ramp, paper, and ink paper (the black one). [carbon paper]

2. TEST 1- Then we let the ball go off the ramp and fall down and land on the ink paper (which is over the white paper). We do each trial 6 times

3. TEST 2- After we set up the second ball in front of the ramp, we let the first ball crash into the second so that they go in opposite directions. We do each trial 6 times.

4. we take the two distances between the ramp and the landing spots of the second test. They should add up to the distance of the first test.

We didn't have time to finish the lab so we will be getting time to do it on Monday.
While half of the class was doing the lab the other half got two worksheets to work on. One was Impulse and Momentum and the other was a chapter 9 review.

I guess that's all so the scribe for Mondays class will be Niwatori-san.

Momentum

Hello to everyone.

What we did today:
1)We got the dvd summary from friday.

2)We went over Chapter 7: Momentum worksheet (answers should be posted below mine, called momentum)

3)Worked on the remaining two worksheets, section 9.1 : IMPULSE AND MOMENTUM, and the Chapter 9 study guide

4)DERIVATION OF IMPULSE MOMENTUM EQUATION FROM NEWTON'S SECOND LAW:

F = m.a = m change in V / change in T
F = m change in V / change in T

Impulse F.t = m.v
Symbol : J
Unit : N.S

Momentum
Symbol : P
Unit : kg . (m/s)

5)The next scribe is Ryan M.
that was all for today's class

Momentum

Momentum

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March 4, 2009 =)

Hello=)
So today, we had to hand in a few things:
1) The DVD summaries from Monday's class. Write a few sentences on what you learned from the video.
2) The friction lab, which was due two days ago.
PLEASE HAND IN THESE ASSIGNMENTS ASAP!!!

After a brief explanation on what we were suppose to hand in, we started a new lab called the explosion lab. It's an experiment that shows each cart's momentum and velocity. Since the cart have different mass, they will have different velocities but they should still have the same momentum.
Once we finished the lab, we were given two chapter 9 (study guide) worksheets.

Here's a site to help you understand a little bit about the cart's momentum. http://www.wfu.edu/physics/demolabs/demos/avimov/bychptr/chptr3_energy.htm

he next scribe is George.
=)

MOMENTUM

hi everyone, it's me Lorenz. so on Monday, March 2 , 2009 we got our Dynamics Test back and as you all can see, someone posted all the right answers for me because that person got 100% (good job!!!). I hope that most of us passed the test.

Mrs. Kozoriz let us watched the video of who i we called Mr. Same Same about out new topic, the MOMENTUM!!! Here are some notes that i gathered through out the video:

1. Momentum = mv
2. Momentum includes inertia and how fast the inertia is moving.
3. Ft = delta mv
4. impulse = delta mv
5. Bigger force and longer time means more momentum.
6. If you lengthen the t, the F decreases
7. Bouncing gives much more impulse than just hitting
8. If you change the momentum each time, you'll have the same impulse.
9. If there's no net force acting on the system, there's no change in momentum, it DOES NOT
mean there's no momentum.

After the video, she gave us a Chapter 7 : Momentum worksheet that needs to be hand in tomorrow, and just before the class ended, we hand in our lab "Coefficient Of Sliding Friction" from last week...

Our next scribe for tomorrow will be Daureen Nacario, have a goodnight everyone and I'll see you all in class....

Dynamics Test Answers

Here are the tests answers !Hover over some of the images for the solutions. There are some mistakes but that is okay
=D