Science class,Tuesday,13,2010

Hello every body!!! I am going to talk about 

the Science class that we did on Tuesday!! First!!!! We got back the quizzes and labs. 

 We started talking about different type forces (Unbalanced and balanced). Different type of friction and made 3 different forces diagram. There are two different type of forces, Unbalanced-force and balanced force. We also played the game with a cord, that a sort of people on one side and another from other side pushing. and more people were from one side and more force they had, less people pushing from the other side and less  force they had. Then we came back and draw three force diagram we draw our self on a line. Then all the type of friction, and explained how Gravity act  on an object moving. And what friction depend on??? Good question. First one thing THERE IS ALL-WAYS FRICTION every where you go, every thing you do there is friction. You make friction just sliding your hand each other,

Softly= less friction

Harder pushing= more friction                  

There are also many types of  friction for example; 

• The static friction (The biggest type of eve),   
• Sliding,
•  rolling, 
• liquid and gas.

The balanced force is the equal forces a

cting on one object in opposite direction, like the picture below.

The unbalanced force is in motion an it push in two different direction, when the forces can't be equal like the picture below.

Friction: the force that two surface exert on each other when they rub  against each other.

Static friction: the acts on object that are moving.

Sliding friction: Is when  two solid surface slide over each other.

Rolling friction: Is when an object roll across a surface.  

Fluid friction: Is when a solid object moves through a fluid.

Gravity: Is a force that pulls objects toward each other.

For home work you need to make three different force diagram, 1 stationary, and two moving. Remember always show where motion goes!!!!

Some link mite help you:

http://www.youtube.com/watch?v=KvQ3YDALMeg

http://zagreb.ceesa.net/course/view.php?id=188

Nest scribe is............Valentina(Vale)!!!!!!!!!!!!!!

I HOPE YOU ENJOYED!!!!!!

Thursday's Science Class

Hello everyone who reads my post!!!                

Today in our science class we talked about force, different types of force, gravity, spring scales, a little bit about friction, and that’s mostly it!

So, first, we watched three short videos about the things I listed (force, gravity). The first video was a man driving a car, this video showed us a few graphs and talked about acceleration. The second video was about a brave person, jumping from a very big height, from the top of the bridge. This video talks about the gravity. And the third video showed us some bicyclist, this video talked about the friction. 

  After that, we talked about the spring scales: what they are measuring, how do they look like and which one is better to use (we had several kinds of spring scales: brown, white, green, yellow, and red). So we (as a whole class) took one object, measured it with the spring scales that were different colors. And these are the results:
1.Green spring scale: 5N
2.Yellow spring scale: 50N
3.White spring scale: 30N
4.Red spring scale: 20N
5.Brown spring scale: 10N
  So, as you can see, the green one was the most accurate. We also had to write, in our notebooks, what we know about Force. These are the things I would like you to know about force:
• A force is a push or pull. When one object pushes or pulls another object, you can say that the first object exerts a force on the second object. 
• Like velocity and acceleration, a force is described by its strength and by the direction in which it acts. (Just a quick reminder: velocity is speed in a given direction; and acceleration is the rate at which velocity changes). 
• Force is measured in the SI unit called the Newton (N). (SI is the abbreviation for the International System of Units, also known as the metric system).
• There are several types of forces: a net forces, unbalanced forces, balanced forces. A net force is the combination of all forces acting on an object. The unbalanced force can cause an object to start moving, stop moving, or change direction. Unbalanced forces acting on an object result in a net force and cause the change in the object’s motion. And balanced forces are the equal forces acting on one object in opposite directions. Balanced forces acting on an object do not change the object’s motion. 
  For homework, we have to read pages 42-50 in our textbooks. Also, some people have to comment for blog. And write the definitions (they are in your textbooks) for the following scientific terms:
• Friction-The rubbing of one object or surface against another. 
• Static Friction- The force that resists the initiation of sliding motion of one object over the other with which it is in contact
• Sliding Friction- rubbing of objects in sliding contact.                        
• Rolling Friction- A force which opposes the motion of any object which is rolling over the surface of another.
• Fluid Friction- Conversion of mechanical energy in fluid flow into heat energy.       
• Gravity- Gravity, or gravitation, is the force of attraction that exists between any two particles of matter (or any two objects). It is the force that holds planets in their orbits around the Sun, or the Moon in its orbit around Earth.                                                    
• Mass- A unified body of matter with no specific shape
• Weight- A measure of the heaviness of an object.
• Free Fall- The fall of an object within the atmosphere without a drag-producing device such as a parachute.
• Air Resistance- Wind drag giving rise to forces and wear on buildings and other structures.
• Terminal Velocity- The velocity with which an object moves relative to a fluid when the resultant force acting on it (due to friction, gravity) is zero.
• Projectile- A fired, thrown, or otherwise propelled object, such as a bullet, having no capacity for self-propulsion.
  At the end of our science class we gave our notebooks, because the Acceleration/ Deceleration Testing Lab was due today. “Have a nice day”, was the last phrase Ms.D said to us today. 
   

The links that might help you learn:
http://www.brightstorm.com/science/physics/newtons-laws-of-motion/law-of-force-and-acceleration-newtons-second-law-of-motion 
http://www.edinformatics.com/math_science/force.htm 
http://www.asknumbers.com/WhatisForce.aspx 
http://www.racemath.info/motionandenergy/What_is_Acceleration.htm 
http://www.theory.caltech.edu/people/patricia/gravtop.html 
http://zagreb.ceesa.net/course/view.php?id=188 

I HOPE YOU LIKED MY POST! ! ! AND THE NEXT SCRIBE IS… (NO DRUM ROLL) MARIA CHIARA! 

Ping Pong, Tennis, and Soccer ball Lab

Tuesday, December 7th's Class

Hey everyone! In class on Tuesday, we started out by checking our previous homework, which was to graph the data for the Ping Pong, Tennis, and Soccer ball Lab! This consisted in drawing either one or three graphs with the data of the lab. After having Ms.D check our homework, we discussed on how to draw a curve line on our graph. These lines helped us to find out the outliers (outliers: points on a graph that have nothing to do with the other ones, and are proved wrong) . Here is a possible example of an outlier:

This graph is showing how fast some boys were running for 3200 meters. As you can see, there is a red line in the middle, which shows the average speed and the average time. All of the dots that are far from the line, are examples of outliers! Notice that some are on top of the line and some are under, showing how some boys took more time to travel the distance than others.

This is a picture of a dotted graph which is similar to the ones that we were working on in class. Even though this graph has the dots connected, we haven't connected them yet.

During the continuation of the class, Ms.D gave us our quizzes back, which we saw, but couldn't keep, since Tamara, Vale and Chiara haven't done them yet. Once we saw our grade, Ms.D gave us the rest of the class to finish the lab.

Here are the questions we worked on:

1) What was your speed for the ping pong ball? tennis ball? soccer ball?

2) What was the speed of the person behind you (down the hill) for the ping pong ball? tennis ball? soccer ball?

3) What was the speed of the person in front of you (up the hill) for the ping pong ball? tennis ball? soccer ball?

4) What is happening on your graph? Please use scientific vocabulary to explain this in a paragraph (5 sentences min)

5) If the hill went down and then back up and we rolled a soccer ball along the entire thing, what you expect the graph to look like and why?

6) What are some of the possible errors in this lab? (4 minimum)

6) In one sentence, explain the main concept of acceleration.

7) In one sentence, explain the difference between acceleration and deceleration.

Here is the link to moodle if you want to print the sheet out:http://zagreb.ceesa.net/course/view.php?id=188

Here is an interesting website that explains what time is: http://www.historyforkids.org/scienceforkids/physics/time/

Here is a video talking about best fit lines and scatter plots...can you identify some outliers in the graphs this man is drawing?? http://www.youtube.com/watch?v=i1uKiZpkl9A&feature=related

Homework:

Our only homework for Thursday is to finish the lab. REMEMBER to do your fourth blog comment for Friday, and 7th graders,keep in mind that by the end of the quarter, you will need to have made four comments to our class, and three comments to the 8th grade blog!!

The next Scribe is......drum roll......Tamara!!!!

Thursday and Friday's Science Class

Hey Everyone!

On Thursday's class we began by Ms. D checking over our Homework which was Acceleration Practice 2. It consisted of 8 math problems where we had to find either acceleration, velocity, or the time. Here is the link to Moodle for Acceleration Practice 2 for anybody who was absent:

http://zagreb.ceesa.net/course/view.php?id=188

The answers for Acceleration Practice 2 are as follows:

1. A= 0.02 m/s/s

2. A= -67 m/min/min

3. A= 1.56 cm/s/s

4. A= -38,733.33 km/h/h

5. A= 156,250 km/h/h

6. T= 1.43 s

7. Vf= -2.21 km/min

8. s=7.57 m/s, T= 2.05 s

After checking the homework, we began working on our Acceleration lab with the three different balls. We could choose to either put all three ball's data on one graph, or three individual graphs. Remember if you're doing only one graph to make three different colors for the balls. This is what an acceleration graph would look like:

This graph is showing acceleration of an object free-falling. For more information on acceleration, check out this website with additional information on acceleration and other types of motion we've been working on. http://www.historyforkids.org/scienceforkids/physics/movement/acceleration.htm

Our only homework for Thursday was to study for the quiz we had last science class (Friday). Here is a link to a video on almost everything that we covered in motion. http://www.kidsknowit.com/interactive-educational-movies/free-online-movies.php?movie=Acceleration

Friday's Class

During Friday's science class we didn't do too much because we were taking the quiz on everything we learned on motion. The quiz grades should be on Powerschool for you to check your grade. After finishing the quiz our only task was to work on the graph(s) for the Acceleration lab with the ping pong ball, soccer ball, and the tennis ball.

Homework

1. Finish plotting all the data on your graph(s). Don't connect the dots because we will be doing that during Tuesday's class.

2. Our fourth blog comment is due on Friday, December 10, by 16:00. Remember that we have to have 3 comments on the eighth grade blog and 4 on our seventh grade blog minimum.

We watched some videos in class on Thursday. The songs are by "They Might Be Giants". The first one is more about motion and the second video is kind of relative, its about the elements.

1. http://www.youtube.com/watch?v=DRb5PSxJerM

2. http://www.youtube.com/watch?v=d0zION8xjbM&feature=related

The next scriber is....... DAVIDE!

This Tuesday in class we first showed Ms.D our homework and then we went right to correcting it. Our homework was to finish Acceleration Calculations. Here are the answers:

1. a= 0.43 m/min/min

2. a= 102 m/min/min

3. a= -0.2 cm/s/s

4. a= 14285.71 km/h/h

5. a= 31578.95 km/h/h

6. a= 98 m/s/s

7. t= 5.10 sec

8. t= 0.09 h


And here is an example how to solve question 1:

vf= 15 m/min 1. a= vf-vi/t
vi= 2 m/min
t= 2 min 2. a= 15 m/min (vf) - 2 m/min (vi) / 2 min (t)
a= ? + acceleration
3. a= 0.43 m/min/min



Next we went over some words that we have to know for a test coming up this Friday. We learned that velocity isn't the same as speed and it means speed + direction. We also learned that acceleration means the change of direction= moving in circles. The formula for acceleration is a= vf-vi/t, but it can be writen in different ways like: t= vf-vi/a or vf-vi= a times t. We also went over the formula for speed which is: S= d/t. We also reviewed the acceptable units for distance, time, speed, and acceleration. Here they are: d= km, m, cm
t= h, min, days, years, sec
s= km/h, m/sec, cm/h, cm/sec
a= km/h/h, m/s/s, cm/h/h,

For Thursday, our homework is to finish Acceleration Calculations num. 2. For more info check moodle: http://zagreb.ceesa.net/course/view.php?id=188. There is also a quiz on Friday, December 3rd, there's a review session at lunch on Thursday. The quiz will be on how to use Formula-Plug-Chug (the math), study how to solve for speed, how to graph speed, how to solve for acceleration, how to make an acceleration graph, and know how to read and explain acceleration and speed graphs. You should also study the vocabulary words from motion to acceleration. Here are the explanations for these words:

Motion- an object is in motion if its distance from another object is changing

Reference Point- a place or object used for comparison to determine if something is in motion (has to be still)
Speed- the distance the object travels per unit of time

Average Speed- divide the total distance traveled by the total time

Instantaneous Speed- is the rate at which an object is moving at a given instant in time

Velocity- speed in a given direction

Slope- the steepness of a line on a graph

Acceleration- the rate at which velocity changes




DON'T FORGET FOR THE TEST ON FRIDAY!!! And the next scriber is BEN!

Acceleration and Deceleration Testing

The first thing we did when class started on Tuesday is we received our graded, bean bag lab rubric. Then we did two math practice problems on page 25 of our textbook, because a couple kids had problems on a few of their calculations for the lab. After that, we went through our "Acceleration Calculations" math practice sheet that we had to do for homework. Most of us had errors with one or two of the questions and they are now homework for Tuesday to complete. Finally, the last thing that we did for the rest of the class period was a class lab, called Acceleration/Deceleration Testing.

The purpose to the lab was:
What does a graph look like when an object is accelerating?

Under that we had to have the IV and DV, which were:
DV: Graph
IV: Object accelerating

Then we went outside to practice with the timers, and then test. Our data was recorded down on three different tables: one for the ping pong ball, one for the tennis ball, and one for the soccer ball. Everyone in the class had a different position at one, two, three, etc. meters, all the way to 12 or 13. I was at one meter (that's why I'm not sure how many positions there were), which was really hard because I had to have little mistakes and be almost exactly on the right times of when the ball started and then reached my point. For each ball, we did three tests just in case of a mistake with the timer, which was surely going to happen. Then under the three trial spots, we had to calculate the average, but we did that when we were done testing and back in class.

Then under the data tables, we answered the purpose question individually, and then discussed it as a class. We concluded that the graph would have a positive correlation because as the time increases, the objects speed also increases.

Then we did a sample calculation, and here is an example of one.
S=d/t
S=1m/1.2s
S=0.83 repeated

And at the end, we had to glue in the small, bottom of the lab page, homework sheet, that we're probably going to talk about next class after we finish the class wide table. It's not homework yet, so don't worry about it now.

That is what we did during Tuesdays class, and the next scribe is Jakub!

Here is a link to moodle: http://zagreb.ceesa.net/

Fridays class

On Fridays short class we worked on acceleration, and as you can see, many other things. We took notes in class, such as these, and Ms.D wrote a lot of formulas and explanations on the board about acceleration. This is all we did the whole class, except for a worksheet we got at the end of the class, which has eight questions on it.

Homework Questions:

• A three toed sloth is moving at the speed of 2m/min. It takes 30min to increase its speed to 15m/min. What is the sloth's rate of acceleration?
• A bicyclist is travelling at a speed of 416m/min when he approaches a hill. It takes him 2 min to travel down the hill. At the bottom of the hill, his speed has increased to 620m/min. What was his acceleration?
• A ball is rolling up a small incline. At the bottom of the hill it is moving at a speed of 5cm/s. Calculate the deceleration of the ball.
• A motorcycle is travelling at a speed of 45km.h. It takes 5s (0.0014 hours) to increase its speed to 65km/h. What is its acceleration?
• A car company claims that the car can go from 0km/h to 60km/h in 7s. What would the acceleration of this car be? ( Seconds should be to the closest 10,000ths when you convert them!)
• A bean bag is dropped out a window. When it falls, it accelerates at a rate of 9.8m/s². If the bean bag hits the ground after 10 seconds, what is its velocity just before it hits the ground? (HINT: What is the initial velocity before the bean bag starts to fall?)
• The same bean bag is dropped out of the same window again. How long does it take for the bean bag to reach the speed of 50m/s? (Everything is the same as above except time!)
• A train travels at a speed of 390km/h can decelerate at the rate of 4500km/h/h (4500 km/h²). How long will it take the train to come to a complete stop?

Relative motion:
-dependent upon an object’s reference point
Velocity= speed + given direction
example= 40 kmph heading north
*GPS*, pilots, air traffic controllers

Graphing Motion:
use a line graph-> shows change over time
Time - on x-axis (possibly)
Distance - on y-axis (possibly)
Speed - on y-axis (possibly)

Slope -> steepness of a line

Acceleration:
Speed increase (positive); Speed decrease (negative); Direction changes (positive or negative)
Speed increase= object starting motion from a stopped point; Speed decrease = object is in motion and is coming to a stop

Circular motion:

• Continually changing its direction
• Continually changes its velocity
• Continually changes it acceleration

To calculate acceleration:
Acceleration=
(Final velocity-Starting velocity)÷Time

http://www.wfu.edu/physics/demolabs/demos/avimov/mechanics/loop_de_loop/loop.rm

The next post is...Nathan!