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

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.