Ben's Scribe Post for Tuesday's Class

Tuesday, March 22, 2011

Hello Grade 7 and 8,


The first thing we did on Tuesday's class was talk about what will happen over the next two weeks. Here is a link to moodle so you can plan ahead. Also, we have a quiz on tuesday (March 29) about work, power, the math for work and power, and all the simple machines. After that, we began the remaining presentations on simple machines.

First up was Nathan and Jakub. Their powerpoint was about the Wheel 
and Axle. I took some notes about the presentation so you can use this post 
as a study guide. Here they are:

• The wheel and axle is a simple machine made of a large wheel secured to a smaller wheel which is called an axle
• It is a rod attached to a wheel and their movements are the same when one of the parts is turned
• Some examples are: a doorknob, a steering wheel, fan, and a windmill
• It decreases distance and increases output force
• Mechanical Advantage= radius of wheel ÷ radius of axle

The next presentation was the pulley by Valentina and I. Here is some 
information about pulleys:

• There are three types of pulleys, Fixed, Movable, and Block and Tackle
• Mechanical advantage= length of input force/ length of output force
• Fixed pulley changes the direction of force
• Mechanical advantage=1
• Examples are fitness machines, flagpoles, and blinds
• Movable pulley decreases the amount of input force required
• Mechanical Advantage=2
• Common uses are in cranes or tow trucks
• Block and Tackle pulley is a combination of fixed and movable
• Its mechanical advantage=3
• Mechanical Advantage for this pulley relies on how many sections of rope there are
• Used to lift loads, fitness machines, and cable cars (gondolas)

The final presentation for Tuesday's class was the screw by Courtney 
and Tamara. They had a powerpoint as well. Here are my notes from the 
presentation:

• A screw is an inclined plane wrapped around a cylinder
• Inclined plane forms the threads on a screw
• Types are countersunk, round head, raised head, coach screw & twinfast
• Names of screw heads are slotted, philips, and crossed slot
• Shank is the space between the head and the threads of the screw
• Core is the rod inside of the screw
• Mechanical advantage= length around threads ÷ length of screw
• Examples - jar, faucet, swirly slide, drill bit, screwdriver, boat propeller
• Increases distance of output force

That's it Tuesday's class. Emilija & Maria Chiara started their presentation, but
we ran out of time shortly after they started. On Thursday they will present, 
along with David and Davide who haven't done their presentation yet. For 
those who are presenting, remember to practice beforehand, know your 
information, and be able to define it. I hope you enjoy reading my post.

Here is a link to a website on simple machines, it has a small quiz on it, so 
you can prepare for next Tuesday's quiz, click here.

THE SECOND TO LAST SCRIBE OF THE QUARTER IS......... DAVID!

Science class, Febuary 17

On Thursday, February 17, Ms.D. gave our quest back. We just finished the section on forces.

Just to remind us this is what we learned about:

Newton’s Three laws:

1) Inertia: Things that are at rest stay at rest, and things that are moving will keep moving unless another forces act on them.

2) Acceleration depends on the object’s mass and on the net force acting on the object.

3) Action and Reaction: If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.

The other forces we learned about are: air resistance, gravity, friction, speed and velocity.

Another important law we learned about was the law of conservation of momentum, which says ‘that the total momentum of any group of objects remains the same, or is conserved, unless out side forces act on the object.

Then Ms.D. explained to the class the goal of our next lab. The goal is going to be making simple machines, and the surprise was that before this lab we are going to make our own super hero, Yeah (scream). We had to design and name a Science Superhero and how this super hero saved the day.

She recommended that his/her power had to be scientific and it had to have at least 5 Superpower. Some examples of his super power would be:

· Decreasing / increasing the speed of an object

· Changing the velocity (speed or direction) of an object

· Changing the friction between two objects

· Conserving / “losing” momentum

· Instantaneous temperature change ( + or -)

· Affecting the weight and gravity of a place

It wouldn't make sense to make a superhero in science class without having scientific powers.

Usually we find superheroes in cartoons, movies and books. But they don’t always use scientific superpower. A good example of a superhero is Superman. He flies in the air without any machine and the gravity doesn’t pull him down.

Our superhero must include laws and forces 0f science like the ones we learned about.

After Ms.D. showed as hers super hero, which she made it just yesterday. She told as that the super hero must be printed in color, and if we though we would lose our super hero she recommended to leave it with her. We went to the upper lab in till the end of the block. When we will came back from the break we will create or story of how our super hero saves the day.

Important Links

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


• http://www.ugo.com/games/superhero-generator-heromachine-2-5

Next Scribe is ............ Tamara!!!

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!

Thursdays Class

Today during our normal science block we started a new project, which was a lab, called "How Long Does It Take a Bean Bag to Drop?" The purpose of this lab was to see how the distance an object is dropped affects the time it takes the object to fall.

We dropped bean bags from different heights:

• the seat of a chair in the science lab

• the lab table

• top of the doorway

• two different heights of stairs.

We dropped the bag three times from each height. That was the fun part!
After we had finished dropping the bags and finding out the time, we had to graph the data we got and the find the average speed. To find the speed you divide the distance by the time. By this time class had already ended, so we finished the rest in the next class. I think that everyone agrees that this was one of the more interesting labs we have done so far. This class was a long class, but there isn't much to say because we only worked on our lab.



Useful definitions for distance, average speed and speed:

Distance: The extent of space between two objects or places.

Average Speed: The overall rate of speed at which an object moves; calculated by dividing the total distance an object travels by the total time.

Speed: The distance an object travels per unit of time.



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

Big Bean Bag Drop for Fun: http://www.youtube.com/watch?v=g0xolhvmbSk



Next Scribe is Ghazaleh!

This video is just to show how the project was done.

Co-authors Ghazaleh, Courtney, and Emilija

Speed, Time, and Distance

Today during the short science block we had time to talk about our homework. Our homework was to do all the questions of the paper Ms. D gave us (Speed Practice Problems). We talked about the answers and talked about how we need to use Formula - Plug - Chug and how we always need to write the formula and the units. If you didn't catch the answers here they are, but be sure to write the formula, the plug, and the chug:

1. An opel car travels 736 km in 8 hours. What is the speed of the car at that time? S = 92 kmph
2. If a horse travels 52 m in 3 minutes what is the rate of the horse? S = 17.33 mph
3. A plane flew for 7.95 hours between Chicago and London, if its speed was 812.7 kmph what was its speed? D = 6460.57 km
4. The speed of a lion going for a kill is 12 m/s. How much time will it take the lion to run 37 m? T = 3.08 seconds
5. If a runner can go 3.25 m/s and runs for 2.32 hours during a race, what is the distance covered during the race? D = 27,144 m
6. A balloon travels approximately at the speed of 46.9 kmph. Calculate the time in hours it takes to tracel 26,578.64 m. T = 0.57

If you lost your sheet you can find our home work sheet on moodle on this link:

http://zagreb.ceesa.net/course/view.php?id=188 and on that link you can also find our next homework assignment. Our next homework is to do the other sheet, Speed Problems #2. The first two are easy, the second two to are getting harder and the last two you need to really concentrate. And remember the triangle: For distance multiply speed x time, for speed divide distance/time, and for time divide distance/speed. And remember Formula - plug - chug!

The next scribe is Emilija!