Transcript File - integrated science 1a!

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Day 3 – Impulse
Mr. Lambert
Integrated Science 1A
Trimester 1, 2014
+ Bell Ringer
What are some of the factors that automobile
designers and engineers must consider when
designing a crumple zone as a safety feature?
Crumple zone – part of
the body of a car that
compresses during a
collision
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Agenda
1.
Bell Ringer
2.
Lab Activity
3.
Impulse videos
4.
Worksheet
5.
Exit Slip
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Learning Targets
On your Bell Ringer
Sheet, write the
following:
We will apply the
concept of impulse in
the analysis of
collisions.
+ Lab Activity
Each group will be given a cart
with a block on it.
Your setup will be as shown in the
image to the right. Instead of 10
cm, you will stack two textbooks.
Your challenge: construct a
crumple zone that cushions the
collision of your car so that the
wooden block does not flip over.
You can use tape, paper, string, and
rubber bands (if available).
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If the challenge is too easy, add 1 or 2 more
textbooks to make the ramp steeper.
If the challenge is too hard, remove 1 book.
+ Answer questions in your notebook
1.
If you managed to complete the challenge and create a good
crumple zone, what designs made it effective?
2.
As you were trying different crumple zones, what designs were
not effective? Why?
3.
How do air bags keep us safe during collisions? Use the
concept of impulse to explain why.
4.
Explain why you bend your knees when you jump to the
ground.
5.
Helmets are designed to protect cyclists. How would the
designers of helmets make use of the concept of impulse to
improve their effectiveness?
Impulse and Crumple Zones
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
http://youtu.be/yUpiV2I_IRI?t=7m37s
Explain
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Impulse Videos
Crash test
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https://www.youtube.com/watch?v=dkM
CFcEkQ0w
Physics of Football
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https://www.youtube.com/watch?v=s6QR
0KdyTFY
+ What is impulse?
Impulse = Force x change in time
Impulse is the same for a collision (as long as the
mass of the object and its velocity stay the same).
A smaller time means a bigger
A bigger
force
time means a smaller force
Compare falling on concrete vs.
falling on grass or a bed
Demo: throwing foam ball vs
lacrosse ball
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Egg throw demonstration
Time to go throw some eggs!
https://www.youtube.com/watch?
v=7RSUjxiZnME
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WARNING! ACHTUNG!
Our target is LARGE.
If you miss the target, you will clean
the egg, you will receive an
immediate referral, and this activity
will end for everyone.
If you think you can’t hit the target,
do not throw the egg.
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Egg Throw
1.
Impulse is the same for a collision (as long as the mass of
the object and its velocity stay the same).
2.
A smaller time means a bigger
3.
A bigger
4.
In this activity, we will apply a force to a moving egg to
bring it to a stop. The egg will be moving as fast as we
can throw it!
5.
Predict: Is it possible to stop an egg without breaking
it? HOW?
force
time means a smaller
force
Explore
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Egg Throw: Free Body Diagram
Egg on the Wall
Force of the Wall
Egg on the Sheet
Force of
the Sheet
Explain
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Exit Slip
In cars built before 1970, dashboards
were made of hard metal. Today,
dashboards are padded. Why is it
better to have a passenger hit a
cushioned dashboard than a hard
metal dashboard? Use the concept of
impulse to answer this question.