Download P wave - LSMS Ms. Benson GT

Shake It Up Baby!
Earthquake in the Classroom
On a piece of your own paper do the following
assignment on today’s lab. Title it Shake it Up
Baby – Seismic-Safe Buildings
 Read Page 74 and 75 Seismic-Safe Buildings
 List six features that buildings have in order to
reduce earthquake damage. Explain how each
works
Introduction
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Earthquakes can cause
much loss of life and
millions of dollars worth of
damage to cities. Surface
waves and body waves from
earthquakes can cause walls
to crack, foundations to
move and even cause entire
buildings to crumble.
Engineers continually strive
to make buildings stronger
to resist the forces of
earthquakes.
Copy this info on your
assignment!!!
P wave (primary wave)
 A type of seismic wave that
compresses and expands the
ground
S wave (secondary wave)
 A type of seismic wave that
moves the ground up and down
or side to side
Surface wave
 A type of seismic wave that
forms when P waves and S
waves reach the Earth’s surface
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Engineers face the challenge of
designing more robust buildings to
withstand earthquakes. Earthquakeproof buildings will bend and sway
with the motion of an earthquake,
instead of cracking and breaking
under the pressure.
Have you ever looked at a really tall
building, such as a skyscraper? What
does it look like? Does it appear
fragile and unstable? It might, but it
is most probably quite sturdy and
can withstand wind, rain and other
natural elements and phenomenon.
Design
Design
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Earthquake-proof buildings will typically
have cross bracing that forms triangles in its
design geometry (like a bridge).
Such buildings also normally include a large
"footprint," or base, and a tapered shape,
decreasing in size as the building gets taller
(or simply, smaller at the top).
Short buildings are more earthquake proof
than tall ones. Why do you think that is?
Have you ever climbed up a tree or been on
top of a playground jungle gym in the wind?
Do you sway more when you are up high
than when on the ground?
All buildings shake at the same frequency as
the shaking of the earth, but the movement
is magnified as the building gets taller.
Sometimes, as can be the case during an
earthquake, a building will sway too much,
crack and crumble and fall.
the area of ground covered by a building.
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You will make models of buildings and
conduct an experiment to test how well
your structures stand up under the
stress of an earthquake. Civil engineers
do this as their job.
You and your partner have 30
toothpicks and 30 marshmallows. The
Earth has limited resources, so
therefore engineers also have limited
resources when building structures.
You will make structures of toothpicks
and marshmallows using only the
materials you have been given. You
may make large or small cubes or
triangles by using whole or broken
toothpicks. You may use cross bracing
to reinforce their structures. Cubes and
triangles may be stacked to make
towers. The towers can have small or
large "footprints" (or bases).
At
the end of class carefully stack your
“building” on a piece of paper with both your
names and your period in the designated spot.
Once your structure is built…
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Draw a sketch of your
structure.
Measure and record its
height, length, and
width.
Line a tray with a
paper having you and
your partner’s names.
Set your structure in it
and put it on the
counter to dry
overnight.

define in your own
words –
cross-bracing,
 large foot-print,
 tapered geometry
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YOU WILL BE ADDING
INFORMATION TO THIS
TOMORROW. PUT IT IN
YOUR FOLDER
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Today we will be testing by
shaking your buildings on a
bed of jello. I will be
doing the motion and you
will record your
observations of what you
see as I go for each
structure.
We will rate each group’s
structure with a
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4 (outstanding)
3 (functional),
2 (iffy)
1 (deathtrap)
Today’s test
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How did your structure do?
Really think about what
works and what doesn’t.
How would you redesign
your structure based on your
observations. Record this in
“I’ve learned”. You should
also be able to explain the
difference between a P wave,
S wave, and surface wave at
the end of today’s activity.
Seismic Waves Demonstration
http://sunshine.chpc.utah.edu/labs/seismic/index
.htm
P Waves
P waves (pressure or primary waves) travel as a region of compression. How
would this appear? Using the diagram above, make the green dots move left and
right. Observe what happens to the distance between the dots.
1.
2.
3.
During compression, the dots move:
A) closer together or
B) further apart.
This wave is similar to the way
A) sound or
B) light waves travel through air.
As a P wave travels, the green dots vibrate back and forth
A) parallel or
B) perpendicular
to the direction of wave travel.
P waves are the fastest kind of seismic wave. A longitudinal P wave has the ability to
move through solid rock and fluid rock, like water or the semi-liquid layers of the
earth. It pushes and pulls the rock it moves through in the same way sound waves
push and pull the air. Have you ever heard a big clap of thunder and heard the
windows rattle at the same time? The windows rattle because sound waves push
and pull on the glass much like P waves push and pull on rock. Sometimes
animals can hear the P waves of an earthquake, but usually humans only feel the
“bump” of these waves.
S Waves
You may think of the Earth as a solid structure, but in fact the Earth’s crust is floating on
a semi-liquid layer of molten rock (magma) just below the crust. Below that, S waves
(shear waves) travel like vibrations in a bowl of Jello.
1.
How would this appear?
A.
B.
2.
Does the distance between the green dots change, or
is the rectangular shape between the dots distorted?
The movement of the green dots is
A) parallel or
B) perpendicular
to the direction of the wave travel.
As an S wave travels, the material is distorted but the green dots do not compress (the
space between them pretty much stays the same.)
S waves are the second wave you feel in an earthquake. An S wave is slower than a P wave
and only moves through solid rock. This wave moves rock up and down, or side-toside.
Because P waves are compression waves, they can move through a liquid. However, S
waves cannot move through a liquid. This is because a liquid is not rigid enough to
transmit an S wave. S waves travel more slowly than P waves and, again, S waves
cannot travel through a liquid.
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1.
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P and S waves caused by an earthquake do not travel in straight lines. They
also do not have a constant speed.
Do you think the wave would
A) speed up or
B) slow down as it moved further from the wave source?
Waves can reflect off (bounce off) of materials that have a different density,
or they can be refracted (bent) as they pass through a boundary between
layers of different material. Scientists use the difference in arrival times of
reflected and refracted waves from distant earthquakes to construct a picture
of what the Earth’s interior looks like.
P waves and S waves have allowed scientists to determine indirectly the
internal structure of the Earth. Because these waves travel at different
speeds through different material, they are also used to help determine the
exact location of an earthquake (epicenter). Remember that these waves are
transferring energy, and that energy is what causes the damage seen in the
crust of the Earth, which is not plastic like the mantle and can break under
pressure (causing faults!).