Wednesday, September 11, 2013Force and MotionMrs. HensleySedgefield Middle School

Do now! On the next available page of your

scientific journal, please respond to the following picture and write 5 emotions that you experience.

READY, SET, GO!

We will be studying force and motion and learn why the twin towers collapsed when they had been designed to withstand such an attack.

Today is the 12 year anniversary of 9/11

In your journal, write this question and your answer to this:

What do you think made the twin towers fall?

Watch the videohttp://www.youtube.com/watch?feature=player_detailpage&v=TJOwttgBpzE

Take notes on the following slides in your scientific journal

I have highlighted the important parts. I will be collecting your journals on Friday to grade. Remember, these are 55% of your grade!!!!

Twin Towers ConstructionStructural engineers who designed the Twin Towers carried out studies in the mid-1960s to determine how the buildings would fare if hit by large jetliners. In all cases, the studies concluded that the Towers would survive the impacts and fires caused by the jetliners.

One theory for the collapse

The Column Theory

Fire generally does not cause column damage in buildings like the Twin Towers. However, could the structural damage and the extra fuel loads of the jets have created conditions for column failure never before achieved?

Damage to ColumnsYou can see how few columns were actually damaged.

Another theory for the collapseFloor Truss Theory

Unlike columns, floor trusses are much easier to heatand will bend and eventually collapse from the fire and heat.

Fire SeveritySurprisingly, the fires were not nearly hot enough to significantly soften the steel in either Tower. The fires in the Towers were small compared to other serious high-rise fires, and were actually getting smaller at the time of its collapse.

Did both the columns and trusses fail?Engineers and architects believe that the Twin Towers collapsed because of redundant designs, which means that when one system fails, the other fails as well. The extreme heat caused both to fail.

So what does this have to do with force and motion?Watch the video:http://gtm-media-2.discoveryeducation.com//v2.3//images/search/d2e07911-bd5f-4fb7-a709-640922777c3d.jpg

Force and MotionNewton’s First Law:An object at rest tends to stay at rest. An object in motion tends to stay in motion.

Force and MotionThe plane was in motion (speed and direction) and the building was not in motion. Did the plane hit the building and immediately stop?

Yes or no?If no, did it continue to travel

forward as it was ripped apart?

Force and MotionThe columns and trusses were engineered to help the towers remain in place when struck by an object in motion. The engineers knew about Newton’s law and knew that if they did not put these safe guards into place, the towers would simply collapse on impact in order to continue with the forward momentum of the plane.

Now compare journals with your table mate Quietly discuss your answers. You have

10 minutes to do this.

Did your note look similar or were they very different from each other’s?

Quietly summarize to each what you learned from today’s lesson.

http://gtm-media-2.discoveryeducation.com//v2.3//images/search/d2e07911-bd5f-4fb7-a709-640922777c3d.jpg

And physics to bring it down

It takes Physics to build it

This was a sad day…Please realize, that we are taking a look at the scientific side of a day filled with terror and loss. Perhaps you know of someone affected by this tragedy.

Exit Ticket In your journal, please answer the

following: 3. Write down 3 things you learned. 2. Write down 2 questions you still have. 1. Write down one thing you would like

to share.