January 5th 2011

We were talking about the alcohol/paper in a vacuum problem today. The question was "Why did the alcohol disappear quicker with no air than with air?"

My group came up with this hypothesis.

• Particles move faster with air. No air particle get in the way

Then the whole class joined together for a group discussion.

Davis said: Without the air there is more room and less resistance so it leaves the paper quicker. And it turns out it was a lot of group's hypothesises. Just different wordings.

Finley then said that that alcohol is made up of parts, like particles. Any thing that makes stuff up. Particles want to move, they don't want to move. They're naturally in motion.

Finley brought up a group and a single person. The group was blocking the single person from doing what he needed to do. It made it harder for the single person to move through the group.

We proved that the alcohol dried faster in the vacuum.

Finley brought another group up and put a chair and a container of ammonia with a group of people around it. It was a group of about 8-10 people. 4-5 girls 4-5 guys. They were instructed to raise their hand when they noticed something. 3-4 guys raised their hands.

Afterwords, we wrote down this;

• Hands rose very randomly
• In general, spread from middle outwards. (Not a perfect pattern)
• Shorter people got it first.
• JF & KK never detected the smell.
• Papi detected it 3rd.

The particles were explored farther;

• they move freely
• they move in a random manner
• they move in a direction.
• moves at random speeds.

Then we revisited the homework question:

If your mom is making pizza on the first floor and your on the second floor, how do you know what she's making for dinner?

A classmate said that you know what she is cooking because the particles in the food makes the scent.

Class ended soon after that. The homework is posted on Finley website.

JG

Monday January 3,2010- Observations and Mechanisms

Today in class, we talked about mechanisms and how to make proper observations. First, Mr. Finley added a liquid to a piece of notebook paper and told us to take observations. He said that observations should be things that we can sense with our five senses. Observations shouldn't be things we think that we know or assume, observations should be fact only. Then we began to take observations on the liquid on the paper. These are some of my group's observations:

-where the liquid hit the paper, the paper turned a darker shade
-the liquid smells like rubbing alcohol
-the paper gets wrinkled where the liquid touches the paper
-the liquid is disappearing
-the larger the spot of liquid, the more time it takes to disappear
-when the liquid was on the colored lines of the notebook paper, the lines blurred

After that, Mr. Finley told us that so far this year, we have been making explanations about the things that we have experimented. Explanations -------> why things happen. He said explained that we were now going to make mechanisms. Mechanisms -------> how things happen. Mr. Finley explained that mechanisms can be crazy ideas, but they have to be testable.
He started us of with an example mechanism for the liquid on paper. Ex. The table soaked up the liquid(the liquid went inside the table). We then started making mechanisms of the liquid on paper at our groups.These are the class's mechanisms

1. It went inside the paper
2. The air took it
3. Some other organism took it
4. When people smelled it the liquid on the paper for observations, it went up their noses

Lastly, we began to test our mechanisms. We made a chart with three columns. Th first column was the mechanism column, second was the test column, and the last column was the prediction column, when you think you are right. We only had time to fill out the chart for the example mechanism.

mechanism column: the table soaked the liquid up

test column: take the table away and repeat

prediction: the paper should stay wet

Before we could actually test the mechanism, the bell rung.

Some advice if people are getting mixed up with explanations and mechanisms. Think of them like this:

explanations=why
mechanism=how

There are some pictures of liquid on paper on the top of the of my post taken at 20 minute intervals.

CS

Circuits 12-22-10

In class today we went onto the phet website and made a parallel circuit that also had a series circuit. Then after we made that and got Finley to look at it there were a few steps we had to take to complete the task.
1. Draw the diagram in your notebook.

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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

12/20/10

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

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

8.4 questions; December 16, 2010

Today, we went over our unit 8 questions.

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

December 15, 2010

We started our class with a problem. We had 3 senerios. A box being lifted by a crane, a box at the top of a frictionless surface sliding down the ramp, and a box being pushed up a frictionless ramp. A and B are the same because they have the same amount of displacement. To convert grams to kilograms you divide it by 1000 because there are 1000 grams in a kilogram. To find the force of a 20 kg object you multiply by 100 and get 200N. To get it up a 2m high ramp it takes 400J because you have to multiply by the hight of the ramp,(2m.)by the force it takes to move the object
(200N). The differnce between force and work is it takes alot of muscle to exert force and no work can be done.
A.M.