Today in Physics....

We watched a video on weightlessness and took down fifteen points about the movie, which we were to hand in to Ms. K.

We then went over the review for the test which is on Thursday. It has been uploaded to the blog.

Tomorrow's scribe is.... Van!

And you better be in class tomorrow...it's bad enough i had to blog for you today! just kidding

Kristin

Space Exploration Review

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Gravity and Apparent Weight

today in class Ms.K handin us a sheet about Gravity and Apparent Weight.in the sheet it define's the weight of a body as the gravitational force on the body and micro gravity and more.it includes some formulas,then we went on review chapter 8 and we answered them.after that we watched a video about the Canadian Space Agency/program,(CSA)..have a good night.
next scribe:Dino

Thursday's Scribe

Sorry guys for the late scribe! Well, friday's class was pretty straight forward. For those of you who were not in class on friday, we went over several sheets and corrected them. Artificial Satellites, Chapter 14: satellite motion, Chapter 10 Gravitation and the duck book questions. Ms. K also mentioned how happy she was to not see Sergio for 3 days! ..

The correction for questions 28 to 33 on page 227 are on the slides.

The next scribe iss.. hall of fame?

Problems 28-33 p.227 (Duck book)

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Wednesday nov. 21 scribe post

Sorry for being a day late. Heres the day's scribe.

During that class we were introduced to new equations:

We also watched the "same-same-guy" video about satellite motions.
Many of the things that we being discussed in the video were review and only a few new topics.
Also Ms K. gave us worksheets.

For thursday's scribe, i picked sandy... i think i told her she was the scribe already but just a reminder.

Gravitational Potential Energy

Okay, in class today, Mrs. K handed back our Transparency Worksheet. After that, we looked over the notes she handed out yesterday.

Gravitational Potential Enegy
From the past unit, we learned two formulas for Potential Energy:
Ep=mgh and Es=1/2kx²

Here's another one that we learned from class today.
PEg= -(Gm₁m₂)/R

From the Newton's Law of Universal Gravitation Fg= Gm₁m₂/R, we increases the separation distance from R₁ to R₂. It requires work and when it is done, the gravitational PE increases.

Derivation of PEg formula:
PEg = ((-Gm₁m₂)/R₂) - ((-Gm₁m₂)/R₁)

Gravitational Potential Well
- two objects that has force of attraction between them having negative potential energy.
- it should rise out of the Earth's potential well to be free of the gravitational force.

For example: If one of the masses is the Earth then the other mass is on Earth's ground level, the total energy is just the PEg since KE = 0 J.

Total Energy = KE + PEg

If the object rises from the Earth's ground level, it would have both PEg and KE, so then, the total energy = KE + PEg.

Escape Velocity
- the minimum velocity of an object to escape from Eath's potential well.

To calculate escape velocity, KE = - PEg but we take the absolute value of the PEg to have a positive velocity so then it will be KE = |-PEg|.

let's say m₁=mass of the object, v₁=velocity of the object, m2=Earth's mass, R=Earth's radius, G=gravitational constant.
KE= 1/2 m₁v₁²
PEg= - Gm₁m₂/R

1/2 m₁v₁² = Gm₁m₂/R

v₁ = √(2Gm₂)/R (m₁ will reduce)

Total Energy and Binding Energy
Binding Energy - amount of additional kinetic energy an object needs to escape.
- it is equal to the negative of gravitational potential energy

on Earth's ground level Et = - Gm₁m₂/R
so, Eb = Gm₁m₂/R

if an object is in orbit at any radius R₁, Fc keeps the object in circular orbit and Fg provided the force attraction between the object and Earth.
Fc=Fg
m₁v₁²/R₁ = Gm₁m₂/R₁² (R₁² will reduce to R₁)
m₁v₁² = Gm₁m₂/R₁

the Et of the orbiting object is
Et = KE + PEg
Et = 1/2 m₁v₁² + (-Gm₁m₂/R)

since m₁v₁² = Gm₁m₂/R₁

Et = 1/2 Gm₁m₂/R₁ + (-Gm₁m₂/R)
Et = -1/2 Gm₁m₂/R₁ or Et = 1/2 PEg

so then the binding energy is Eb = 1/2 Gm₁m₂/R₁

After the discussions, she handed out a worksheet called 'Gravitational Potential Energy Questions'.
Here are the solutions.

1.) PEg = - Gm₁m₂/R
= (- (6.67 * 10^-11)(500)(5.98 * 10²⁴))/ (6.37 * 10⁶)
= -3.13 * 10⁶ J

2.) Et = Ek + Ep
= 1/2 m₁v₁² + ( - Gm₁m₂/R₁)
= - 1/2 (Gm₁m₂/R₁)
= - 1/2 ((6.67 * 10^-11)(5.98 * 10²⁴)(500))/ (4.22 * 10⁷)
= - 2.36 * 10⁹ J

3.) Etave. = Et(in orbit) - Et (on Earth)
= -2.36 * 10⁹ - (-3.13 * 10¹⁰)
= 2.89 * 10¹⁰ J

4.) Eb = 2.36 * 10⁹ J is needed to remove satellite from Earth's orbit.

5.) Ep = - Gm₁m₂/R
= (- (6.67 * 10^-11)(5.98 * 10²⁴)(2000))/ (6.38 * 10⁶ + 400 * 10³)
= -1.18 * 10¹¹ J

Before the end of class, she handed out notes about Escape Speed and asked us to do Questions 28,29,30,31,32,33 in the duck book. I guess this is the end of my post, I hope i covered everything.

Next scribe is Russel L.

Planetary Motion

Universal Gravitation Answers

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orbits

Hey its Ant. Sorry for late post. Been busy with work and family matters. But any who recap of Friday's class.

Mrs. K gave us a wonderful new song to learn with lyrics. Inverse square law by Michael Offut. I will be getting Chris his CD for Christmas. Next we finished off the class with a video on Kepler's three laws. I learned a few things from this video such as Mar's orbit is actually an ellipse and not a circle, Kepler's three laws of, course. They are as followed :

1. r = ED/ 1 + cos θ
2. DA/DT = constant
3. T^2 = (4π^2/GM ) a^3

By the end of class she gave us 3 homework sheets. They are:
1. chapter 11 gravitational interactions
2. concept - development practice page 12-1
3. Universal law of Gravitation

don't forget your projects are due on Wednesday, Dec. 5...i think.

next scribe is JEV

Scribe - Wednesday, October 14, 2007

Today we did numerous things. First of all we went over the test. The answers are posted on the blog. Next we got a chapter review worksheet to work on followed by a lab called, "The orbit".

A pink sheet was handed out called the Grade 12 physics project: exploration of space.

It is due wednesday dec 5 2007!
worth 50 marks
MUST BE SUMMARY, NOT READING YOUR PROJECT!
Also needs references.

Next scribe is....
111111111!

Circular Motion/Work and Energy Test Answers

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Scribe for Nov.13th

Okay i'll make this short and sour, we did a test, i failed, WALLAH! andrew's the scribe.
Have a Nice Day. =)

So today in physics class we got our lab back that we did on wednesday on potential energy , where we had to find the relationship between the extension in an elastic spring and the applied force. We also went over three worksheets that were given to us last thursday by ms.k,, the 3 worksheets were:
1. Section 5-3, Diagram Skills
2.Concept Development Practice Page 8-1
3.Concept Development Practice page 8-2
Next scribe for tomorrow will be Mr.Ferrari(Steven) haha.

Work Skills Sheet

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Friday's Class

Ok so today in class we saw a video of the same-same teacher about energy. We also got to wake up Victor from falling asleep listening to his Mexican music haha. Well I finally got to finish my lab so that was my greatest accomplishment today as well. (it helped me getting over all the "soldier boy" jokes everyone was making) Well, we wrote down 8-10 points from the video and handed that in for marks, and since we finished watching it some 15 minutes before the bell we used that time to work on our four sheets given yesterday. Next scribe can be Victor "Living La Vida Loca" Baez lol

PS. Victor, did I even spell that right?

Scribe Post 2

Hello again, I am once again scribe for physics. The November 8th class was not a class that we had done a lot with, instead Ms. Kozoriz let us use the extra time to finish up our labs that we had done on Wednesday. Ms. K also gave us four worksheets to complete that have to be completed by Monday Nov.12 because our test is now moved to Tuesday Nov. 13. It was changed because Ms. K gave us an extra day to study and finish up the worksheets she had given us over the last week. The next scribe for Friday's class will be Renan.

Hooke's Law

Today in Physics class....

FIRST

We went over the questions in the duck book (MS. K has posted the answers below).

SECOND

We learned about Hooke's law of elasticity which is "an approximation that states that the amount by which a material body is deformed (the strain) is linearly related to the force causing the deformation (the stress)."

Note the following equations:

Hooke's Law

F=kx

Spring Potential Energy

Es=1/2kx²

Gravitational Potential Energy

Ep=mgh

THIRD

We were given a lab that was related to Hooke's law. There are questions included in this lab and it will be due tomorrow although we are supposed to be getting some time to work on it tomorrow as well.

The equations you see above should come in handy if you're trying out the questions for the lab.

Sorry this isn't the most extensive post, but I've got work soon and I still need to work on my lab.

Tomorrow's Scribe will be....

DINO

Work Questions

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Scribe

Hello everybody!

Today was the day we learned about energy! But before that we just went over a bunch of problems relating to work. Just gotta remember:
Work = Force * Distance
Work = Force * Cos theta * distance
(the Cosine theta find the component of the force that lines up with the distance)

Then we moved onto the video lesson, which summed up kinda goes like this:
- Review of Ft = momentum
- Then we learned that Fd = Energy or work = energy
- Energy comes in many many many forms electricity and light to name a couple
- From there it moved onto Kinetic and Potential energy
-Kinetic energy is the energy of motion
-Potential energy is stored energy
-They are related, when potential energy is transformed into motional energy the total energy stays the same by the law of conservation, so if 5J of PE is transformed into Kinetic energy there will still be 5J of energy in the system (assuming that which is transferred to the surroundings is negligible)
-Then with a brilliant demonstration on pulleys he showed us how each rope takes some tension force but the person would still have to exert the same amount of energy to move the object because they would have to pull a larger distance.

That pretty much sums up the class...
The next scribe will be KIM

SORRY!!!

Sorry guys, I started my scribe, but it's a long one and I have to go to work now =(

So it'll be up around 11:30, very sorry... maybe you guys can check it tomorrow if you don't want to stay up that late...

Craig

Scribe #2 (wow, it sure is a huge gap between the first and second scribes)

Very sorry about the tardiness of the scribe... I worked from 6:00-11:00 tonight and it was a long one today, so... read this before our test for a good review =D
Well, we started off the class with Mrs. K. going over the handout on "WORK: A DEFINITION". It reviews the concept of work (with Force and Displacement as its two essential elements).
an example of these elements are in the diagram: "F" being force, and "d" being displacement

Work ("W") is Calculated by the following equation with the same parameters from the diagram above.
The next topic was on "Work Done by a Variable Force". This means that while the work is being done over the displacement interval, the Force is not constant throughout and therefore, the equation of W = F • d will not work. In this case, the graph of the Force vs. Displacement graph would be that of a curve or line with a slope x<0as seen below) .
Now, one can imagine (should be easy for Calculus students) that as the number of these rectangles increase infinitesimally, the size of the intervals will begin to become smaller, and smaller, and smaller... and continue as such forever, infinitesimally close to zero, such that the rectangles could be said to have a width of the exact point on the graph. At this point in time, if the areas of all these rectangles are added together, we would get the Work done... why? because area of these rectangles as we said are A = b • h or A = ∂d • F and since ∂d • F = W, then A = W. So basically, the area between the graph and the x-axis is equal to the Work done.

WOW!!! That was a lot of explaining... anyways, next we took a look at Work being positive or negative. Now it can be either, depending on the direction of the Force relative to the displacement, if the Force is acting in the opposite direction of the displacement, the Work would be negative. So to support this, if the Force were to act in the same direction as the displacement, the Work would have to be positive. ***However, if the Force is acting (or has a component acting) neither in the opposite nor the same direction and is perpendicular to the displacement [eg. Force acting UP, displacement to the RIGHT], the Work is ZERO (0)***

The next section dealt with Work and Force at an Angle.
Basically, the Force acting upon the object in question is doing so at an angle (Ø). However, this angular force is not used to determine Work, only the Horizontal component is used in the calculation. (or the vertical one if it is parallel to the displacement in question). The way to calculate this horizontal component is given by Fx = F • cos(Ø). Therefore, to find the Work of an object moving as a result of an angular Force, we must use W = F • cos(Ø) • d.
Finally we briefly looked at the calculation of Kinetic and Gravitational Potential energies. Kinetic Energy (KE) is said to be: the work needed to accelerate a body of a given mass from rest to its current velocity. Gravitational Potential Energy (PE) is: the energy that an object of a given mass has by virtue of its position relative to an arbitrary "zero ground". The formulae for these are as follows:
Finally, we finished off class with a couple questions from the "SPORTS BOOK"!!! (Duck Book). We will be correcting those in class tomorrow (p. 330 q's: 1-6)

That's all for tonight, very, very, very, very sorry for the late scribe... Hope this will at least be useful for test review. Thanks, and tomorrow's scribe is...

Grey-M!!!

POWER WORKING

I don't have any idea who picked me as the next scribe. So, I went back and traced the trail of scribes. It seemed like it was SERGIO?! Sorry, Sergio. I MEANT BRYAN HAHA! So, We basically finished the CIRCULAR MOTION unit, given that we started working on POWER and WORK.

We learned that:

• WORK is the product of force exerted on an object and the distance the object moves in the direction of the force. It has no direction and is therefore considered a scalar unit. WORK is measured in JOULES. It is calculated using the formula:

W = fd

• POWER is the rate of doing work or the rate at which energy is transferred. Power is measured in WATTS. it is measured using, where t is time:

P = w/t

Today in class, we did two GRUELING labs (just kidding). The first lab was about calculating our own work and power as we go up the stairs. First, the height of the stairs was measured, then the we recorded the amount of time it took for us to climb up the stairs at a constant pace. We needed the mass of the participants so we can calculate force using F = mg.

The second lab involved a cart with one kilogram of weight on it. The cart was held on top of a 30 cm-high incline, and was released going downhill. The time it took for the cart to travel one meter from the base of the incline was recorded. Three trials were done to acquire a much better result. Further calculations were made.

For both labs, questions were answered and were taken home as well because NOBODY finished them. Discussions about work and power will continue on MONDAY! I hope everyone has a great weekend! I'm not having a fun one so far because I got stuck at home.

I think I've covered everything we did in class on Friday. OH WAIT, Mrs. Kozoriz didn't give us candies! Anyway, do your labs over the weekend and see you guys on Monday!

The next scribe is... CRAIG.

All Saint's Day Scribe

Today's physics class, we had a substitute; Mr. Skyrnyk. We corrected the sheets we got yesterday, including our Study Guide. Then he handed out sheets and a stapled booklet. We worked on the first couple pages of the stable booklet, and I'm not sure if they're due or not. That's about all we did today. Tomorrow's scribe post will be covered by Vincent.

&I'm done. Woww.. scribing for Physics is so pointless.