Wednesday, December 22, 2010
Circuits 12-22-10
1. Draw the diagram in your notebook.
.
2. Identify which are in series and which are in parallel. Why.
My answer to question two was that light bulbs A, B, and C are in series because they are all connected by the same circuit. I then said that light bulb D was in parallel because it wasn’t in the same circuit but its circuit used the same batteries as the other circuit. I’m not sure about those explanations on parallel and series so if someone could comment on this than it would be helpful.
3. Describe the electron movement when it is close to fewer light bulbs and when it is close to more light bulbs.
The electron movement gets faster when it goes to the single light bulb (D) and the electrons slow down when they get close to the series of light bulbs (A, B, C).
4. Why does this happen.
I think this happens because there is less resistance when it goes to the single bulb so it can go faster, but when it goes to the multiple light bulbs there is more resistance so the electrons slowed down.
Also don’t forget that we have a quiz tomorrow!
-DB
Monday, December 20, 2010
Fin asked us about self controll. He asked Steve to go up and break a light bulb that he wrapped in a shirt. Steve broke it. Finley passed around the bottom part of the light bulb. Ha asked us if we could trace the path of the wires in the bulb and tell if it was important or not. When we examined it there was a spring on the top connected by 2 rods that went down through the glass that holds everything together. We had to draw what we saw in our notebooks. We also had to answer the ?s "where do the wires go" and "why is it important". We saw that the wires came out of the bulb and did not touch the bottom of the bulb. This was important because if it were to touch the bottom of the bulb, then the electricity would just circle around in one spot. The wires also go out because the electricity needs to find a way out of the bulb to go outside. Fun then passed around the bulb again to see if we could finfd evidence of the wires coming out. My group found where the wires were coming out- one on the side and one coming from the bottom. FIn asked why the wires were going in 2 different places. Then, fin brought back up the whole plastic parachute senario when he rubbed the parachute on Sasha and Yamato's head. He said that when you rubbed it on your hair, you are releasing electrons creating static electricity. He then rubbed the chute onto several people's heads and said that this realeased positive energy. Anthony said that it released electrons that traveled from the desk onto the chute then to the head. We then watched an Irish movie about electricity. In the movie they said that traffic also creates static electricity. Then they moved on to electrical circuits. They said that an electrical circuit is a circuit that makes electricity move around. They gave pictures of circuits. ON circuit, the parallel circuit, has electricity that goes around in a circle. A series circuit is where the circuit goes to more than one place at once. The movie moved on to telephone wires and that good stuff and how the high voltage can kill a person. This happens because the human body is mostly made up of water, and since water has a strong reaction to electricity, the shock can kill a person. Then they explained that a wat is equal to a jewl or newton (Fin pointed that out). THe movie moved to how electricity also creates heat and fuses. They then explained that life would be very difficult without electricity. The movie ended after that. We talked about the movie and their accents after the movie was done.
There is a test tomorrow along with a study session at 7:00- there might be donuts
:-)
WR
Friday, December 17, 2010
Energy and Circuits- P2
Today we went over our homework from Phet.com. Our homework was to create a circuit that lights a light bulb. After creating it on Phet.com, you can see how the current is passed from the battery to the bulb through the wires. In order for the current to work, you need an energy source (battery) and a place for the energy to be recieved (light bulb)with a switch to turn it on. If you have an open circuit, energy cannot be passed through.
A closed circuit is a complete circuit where the energy can be passed through in a circle.
A resistor is a tool that you can add onto your circuit which can slow down your current and dim the light.
If the circuit has a too high of a voltage, it will catch on fire.
Energy cannot pass through a dog.
Energy can pass through metal a lot easier than a non-mental object.
The blue dots that pass through the wires are the electrons. Electrons are a part of an atom. The electrons preform kinetic energy while traveling throught the wires.
Another thing we've briefly talked about was static electricity. After rubbing hair with plastic the result was that it stood up. This is caused by electrons. The electrons from the plastic was rubbed onto hair which made it stand up.
S.D
Thursday, December 16, 2010
8.4 questions; December 16, 2010
8.4 a. A roller coaster pulls the cart to the top of a hill by doing 150,000 J of work on the system. The internal energy of the system changes by 50,000 J. How much more kinetic energy does the system have when the cart makes it back to the bottom of
the hill?
Remember, to get to kg from just grams, you have to divide by a thousand or move the decimal point three times to the left. Afterwards, you have to multiply kg (mass) by 10 to get the force. Once you have found what the force is, you use the formula "Force * Displacement = Work" In this case in 8.4, you have 3g. 3g divided by a thousand is 0.003. Times that by 10 to get force or 0.03. So now, force= 0.03n.
Now, in the formula Force * Displacement = Work, we haven to substitute Force in for 0.003n. Also, work is substituted for 50J. Now we can modify the equation to "Displacement = Work/Force. One J is equal to 1n * 1m.
Force * displacement = Work or Displacement = work/force
0.3n *166.667 = 50j or 166.667 = 50/0.3n
I had to skip 8.4 b so now we are on 8.4 c.
8.4 c. A meteoroid, moving with high speed, enters the Earth’s atmosphere and falls toward the Earth. As it passes through the atmosphere, it warms due to friction with the air. When it hits the ground, it creates a giant crater. Explain the process using any or all of the ideas of work and energy changes (consider all possible types of energy change). Include a work-energy bar chart.
In this problem, the system is the Meteor. We have Kinetic energy in the Initial state with work then added to equal Kinetic energy with Internal change energy in the Final state. In this problem, the earth is doing the work.
8.4 d. A skydiver who jumps out of an airplane at 3500 m above sea level accelerates towards the ground for about 15 seconds before the upward force exerted by the air on the skydiver is about equal to the downward force exerted by the Earth on the skydiver.
a. Draw a force diagram for the skydiver after she/he has been falling for about 15 seconds.
There should be Grav. pot. energy and Kinetic energy. Also, there should be negative work which equals out to less Grav Pot. energy and less Kinetic energy
b. The skydiver’s speed remains constant at 55 m/s until he or she opens the parachute. Choose the skydiver, the Earth, and the air as the system. Draw
a work-energy bar chart that describes the skydiver’s fall from when he or
she leaves the plane until just before the parachute opens.
Comment if I left anything out or messed up anything!
Class work and HW: Go to Google and search for PHET and play Sims
click on first link
go to physics
Then electricity, Magnets and circuits
then go to circuit construction kit
Create a machine that lights a light bulb and explain how it works!
Most likely there's a test Tuesday!!!
BB
Wednesday, December 15, 2010
December 15, 2010
(200N). The differnce between force and work is it takes alot of muscle to exert force and no work can be done.
A.M.
Tuesday, December 14, 2010
December 14 ,2010 - Starting to Going Over Lesson 8
Today in class we started by finishing watching Mythbusters.
After we finished watching the video, we went over lesson 8.
8.1 a) We said that the Americans With Disabilities Act is concerned with the steepness of accessibility ramps because there shouldn't be too much force (not work) needed to go up the ramps. It isn't about work because the amount of work stays the same no matter how steep the ramp is. This is because when the ramp becomes less steep, there is less force but the distance increases.
b) since the ratio for the height and width of the ramp was 1:12, I said that possible ramps are 3m by 36m, 5m by 60m, and 12m by 114m.
c)I said that ramp "iii" fits the requirement.
In class we learned that you can find how much force needs to be applied to something by doing (Mass * 10). This is only true with kilograms so if it is in any other units, it must be converted into kilograms.
d)
i) To find out how much work is done on that ramp, we needed to know that Force * Displacement = Work. Using this rule, Mass * 10 = Force, we found out that we would need to apply 200N. The height of the ramp was 2meters so the displacement is 2m. By doing 200N * 2, we found out that it would take us 400J of work to push a wheelchair up the ramp.
Class ended so we did not go over the rest of problem d)
I was still confused about why we take the height of the ramp for displacement and not how much you traveled/moved the wheelchair
-AT
Friday, December 10, 2010
Decmber 10, 2010 Period 2
http://www.npsd.k12.nj.us/20222069133223760/blank/browse.asp?A=383&BMDRN=2000&BCOB=0&C=59194 here is the link to the page for Energy Activities. Its on the bottom of the page.
GS
Thursday, December 9, 2010
energy activity sheet
Tuesday, December 7, 2010
Tuesdays Blog
Monday, December 6, 2010
Monday, December 6th: Skateboard Problem
a) Draw a picture of your track.
(shown above.)
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Place the skateboarder on the track and observe the motion. You can investigate further by changing the skate or you can scroll down and adjust the fiction. Choose two different situations from the simulation that you can analyze and then share with the class.
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1. My first situation is on Earth, with the PhET skater. The track is my original track shown above, and the friction is none. I observed that the skater keeps on going at a consistent speed and it pauses for the same amount of time when it reaches the ends of the track every single time.
2. My second situation was using a bulldog on the Moon. The track is still my original track, but the friction is medium. I observed that the bulldog wasn't able to move as fast; in fact it couldn't even go through the loop because of the friction. Things on the moon are supposed to be lighter, so friction can really slow someone down.
b) Describe or draw your chosen initial and final states
initial final
c) Include your choice of a systems
My choice of the system is the Earth and the skater.
d) Create three different representations (i.e. picture, bar chart, force/motion diagrams, number statement, graphs, etc) to demonstrate the changes that occurred during the process.
40J + 20J = 20J + 40J
Friday, December 3, 2010
Friday, December 3 - HW Review & Elephant Project
Then, we went back with our groups to work on the elephant project. We started the elephant project two days ago when we watched a video to start us off. The video was about an elephant that steps onto a trampoline. It shows the elephant walking up the steps, and starting to jump on the trampoline and jumping on it. Mr. Finley gave us a task to find 5 things that related to energy from the video, draw the intial and final states, bar charts, and number sentences. There was also an additional question which is: "Is the elephant situation realistic in terms of physics and energy?
You can watch the video at:
http://www.youtube.com/watch?v=TK27aknWVI4.
A.L.
Thursday, December 2, 2010
If you want to see the video go to youtube.com and type in elephant jumping on trampoline
Then we went to a website(colorado.edu) and played a game energy skate park. It was a person on a ramp going back and fourth.
-MM
Wednesday, December 1, 2010
Energy Bar Charts and Project
Here is the video:
Nothing as of 4:30. As we all know, Mr. Finley posts homework by 4:00 so it is safe to day there is no homework.
Here is the webpage