Energy Bar Charts and Project

Today we first started to work on our bar chart packets. They have to be done by today, or you have to come in during study hall or homeroom. If you were absent, then check with your group to get the answers.

Then, Mr. Finley called up our groups to check our homework, the bar charts for the skier problem and lifting a ball problem.

To check this we are going up to Mr. Finley computer with our groups. We are to view two PowerPoints with all of the answers on it, and compare our answers. This will be available tomorrow as well, so don't worry if you didn't get to it.

Then we were called up to the front by groups to be told about a project. We have to watch a video about an elephant jumping on a trampoline, see 5 thing in the video that relate to energy, and choose 2 that you can analyze and share in class. We have to draw or describe initial and final states. Then we have to include your choice of a system. Third, we have to create three different representations that show the changes of energy that occurred. You can use a picture, bar chart, number statement, descriptions, etc. Finally we have to answer if the the elephant situation is realistic in terms of physics and energy. Remember, this is a group project. You don't need to start it at home.

Here is the video:

Tonight's homework is:

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

I am somewhat confused about what the difference between energy conservation and energy constant. Can somebody clear up what these two terms mean and how they are different?

Thanks!

MK

November 30, 2010

Today in class, the first thing we had to finish up was to go over the ski problems and to make sure that you made the bar charts for it. Bar charts should look like this.

Rasing the Bar packet must be done and you should almost be done with the Energy packet.

You also have to go over the homework that is due today and start making bar charts for all of the problems.

Energy Packet

1. The first problem was that Jessica stands on the 1st floor of the elevator. The door closes and she goes up to the 4th floor. Jessica and earth are in the system.

a.) Jessica, Earth, and Elevator

b.) Initial is when she is on the 1st floor. Final is when she is on the 4th floor.

c.) Creat own work-energy bar chart

2. Alan's Solution

a.) We agree with Alan and his charts are correct and so are his answers.

b.) The chart helps him see the changes from start to end and the amount of work done.

c.) They show the amount of work and energy in the system.

d.) He found out that displacement * force = work and he found the lengths of the bars.

3. 4.5 Reason

a.) The work and the final energy would be split in half.

b.) She would still have GP energy but less than if at the top. She would not have kinetic because the elevator moves at a constant rate.

c.) 0+1000J=1000J

That's all we got done in class.

-Yam

Class on 11/24

In the beginning of class, he told us that:

we are going to start a group project on Tuesday. The bar chart packet must be done by then.

We had everyone break up into their groups as usual, and the "skier people" looked at a PowerPoint presentation on his laptop, and we need to remember some of it for the homework.

The homework for the "elevator problem people" is to do the skier problem, and for the people like my group, "the skier problem people" is to correct and explain any mistakes you made using the PowerPoint presentation that we looked at in class.

I have a question for everyone out there: for the system for the skier problem, why is the mountain not in the system?

And, if you don't get how to make bar charts for the skier, I have a hint; he tells you what the system is in one of the old hws, and those are labels. Here's what the old hw was:

-MA

11-23-10 Elevator problem

We started out in class with going over the blogging rules:

• You must comment twice a month


• November and December are going to be combined, so you have enough time to make your tow comments.
  
• The comments should be either a question or correction.


• Answering a question counts as a comment.


• Your comment should be on a recent blog, otherwise no one will see it and respond.
  

The picture is what a bar graph would look like.

Next we began to work on a few problems with the bar graph packet.

It was: $20 in your wallet, $60 int he bank, and $20 pocket.

If you take $20 out of the bank, and put it in your pocket what would the bar graph look like now.

We would then draw a picture of the change. This is what the rest of the bar graph packet was like.

Then we got into groups, mine was going over the elevator problem.


Say the elevator is 1000 N and Mary is 100 N the weight now is 1100 N the elevator height is 10 meters, how can you figure out how much work was done?


Force* displacement=work


1100* 20= 22000 J

We got 1100 form the weight of Mary and the elevator, and we got 20 because we drew a picture to help us figure out how much distance the elevator would have to go..


Next we had to figure it out if Marys twin sister was on it, we assume she weighs the same.
Mary is 100 pounds, and her twin is 100 pounds

1200*20= 24000

N=Force
Meters= displacement

If we went on the elevator for 4 floors instead of 3, it would be:

1100*30= 33000

1100 because of the weight of the elevator and Mary, and 30 because of the amount of meters between the floor of the first floor and third.

Something I am a little bit confused on is how to make an integer statement. If anyone wants to comment and tell me how, that would be good.

KK

Bar Charts

Thursday, November 18

We started the class by going over the homwork.

The homework problem was:
Eugenia slowly lifts a box by exerting a constant force of 5n. She moves the box from the ground up onto the table, which is 1m high.

Here are the questions on the homework:
1. Draw a picture of intial and final state for the box while she is lifting it.

2. Calculate the work Eugenia has to do in order to lift the box onto the table.

3. Dicuss the energy transformation and write a number sentence to express what occured.

4. Suppose Exerted a larger amount of force on the box at the beginning. What would she have to do to get the box to stop when it got to the table?

We also discussed this question:
Mary rides in an elevator from the first floor to the third floor. Answer the following questions.

Here are the questins:
1. Sketch the intial and final states, and then identify the system.

2. Make a reasonable approximation for the force applied and the distance between the floors in the building.

3. Write an integer statement for the work the elevator does to lift mary to the 3rd floor. Find the work.

4. How much work would the elevator have to do if marys twin sister joined her?

5. How much work would the elevator have to do if mary decided to go to the 4th floor instead? (find the work for both cases: with and without her sister)

-SA

November 17th Wednesday Period 2 (Spring Story)

We started by discussing the homework. We had to describe changes in energy in a story.

1. The spring is pushed down

2. then its released and shoots

3. then it stops going upward and is in midair.

4. it next starts to drop

5. lastly it is caught

On the white boards we wrote the energy transfers for each step and discussed it as a group.

1. We agreed that there was positive work done that transfered it from no energy to elastic potential energy.

2. For this one the spring changed from elastic potential energy to kinetic energy.

3. No the spring loses all of its kinetic energy but has gravitational potentioal energy.

4. The spring loses gravitational potentioal and does downward gaining kinetic energy.

5. Finally the spring is caught where there is negative work aplied to the spring to make ot stop.

We next lodoked at a table with various amounts of force, displacement an work.

We instantly saw that the force times the displacement equals work. Mr. Finley then told us to think of what negative work is. Many groups came up with the idea that negative work is the opposite of work such as negative kinetic energy would be slowing something down or stopping it.

-JP