
1. 
Before conducting the
experiments, you must build the tabletop earthquake generator.
(Materials for the generator can be found at your local hardware store
or a large home supply center.) Consider asking a few interested
students to help build the generator, which is shown below with a sample
test structure.

2. 
Follow the instructions below to assemble the tabletop earthquake generator.

Cut the PVC pipe into two 24inch pipes and two 30inch pipes.

Drill a .25inch hole 2 inches away from each end of both 24inch PVC pipes.

Glue the PVC pipes together to form a rectangular frame.

Insert and fasten the eyebolts into the holes.

Loop a rubber band around each of the eyebolts.

Lay the dowels or pencils across the PVC pipe and allow them to roll freely across the pipe.

Drill four .25inch holes at
each corner of the board. The holes should be 2 inches away from the
edge of each of the four corners.

Insert a hex bolt into each hole. Fasten the bolt to the plywood with a nut.

Place the plywood on the wood
dowels or pencils. Stretch the other end of the rubber bands under each
hex head. Tighten the pieces into place.

3. 
Discuss with the class the
different variables that need to be considered when constructing a
building durable enough to survive a catastrophic earthquake. Help
students understand that the following factors contribute to the
durability of a structure:

Distribution of weight

Variation in shape

Variation in height

Variation in foundation material

4. 
Explain to students that they
will be constructing their own miniature buildings to test these four
factors. Before they begin, have students do some initial research on
earthquakes and earthquake engineering. Encourage them to look for
information regarding the four factors that contribute to the durability
of a structure. They could begin their research in class and continue
as a homework assignment. The Web sites below offer a good starting
point for their research:
MCEER—Multidisciplinary Center for Earthquake Engineering Research
Earthquake Engineering Research, University of California, Berkeley

5. 
The next day, divide the class
into four groups. Explain that each group will build different
structures and then see how durable each is by placing it on the
earthquake generator and simulating an earthquake by shaking the
generator. Each group will be testing one of the variables discussed
above. Before conducting the experiment, each group should make a
prediction of which structure has the best chances of surviving an
earthquake. Students will record their predictions, observations, and
conclusions on the Classroom Activity Sheet: Earthquake Data. 
6. 
Listed below are the variables that will be tested and the steps the groups will follow:
Experimental Group 1: How does the distribution of weight within a structure affect its stability during an earthquake?

Students in this group will
make two rectangular, solid blocks with dimensions approximating 15 × 15
× 20 centimeters from light materials such as Styrofoam, cardboard, or
foam board. The third block should be made of a heavier material, such
as wood. The wood block, placed at different positions during each
trial, is the darkcolored block in the drawings below.

Predict which structure has the best chance of withstanding an earthquake and explain why.

Place each structure on the earthquake generator and simulate an earthquake by shaking the generator.

Observe which structure was the most durable and withstood the earthquake.

Write your conclusion and revise your original explanation if you disproved your prediction.
Experimental Group 2: How does
variation in shape and placement of objects within a structure affect
its stability during an earthquake?

Students in this group will use three different rectangular, solid blocks made from the same
material (either Styrofoam, foam board, or cardboard). Make one block
15 × 15 × 20 centimeters, one block 10 × 10 × 20 centimeters, and one
block 5 × 5 × 20 centimeters. In each trial, the blocks will be stacked
in a different order, as shown in the diagrams below.

Predict which structure has the best chance of withstanding an earthquake and explain why.

Place each structure on the earthquake generator and simulate an earthquake by shaking the generator.

Observe which structure was durable enough to withstand the earthquake.

Write your conclusion and revise your original explanation if you disproved your prediction.
Experimental Group 3: How does
the variation in the height of each structural element and its
placement affect the structure’s stability during an earthquake?

Make three different rectangular, solid blocks out of the same
material (either Styrofoam, foam board, or cardboard). Make one block
15 × 15 × 30 centimeters, one block 15 × 15 × 20 centimeters, and one
block 15 × 15 × 10 centimeters. Have students conduct an earthquake
trial in the orders shown in the diagrams below.

Predict which structure has the best chance of withstanding an earthquake and explain why.

Place each structure on the earthquake generator and simulate an earthquake by shaking the generator.

Observe which structure withstood the earthquake.

Write your conclusion and revise your original explanation if you disproved your prediction.
Experimental Group 4: How does variation in foundation material affect the stability of a structure during an earthquake?

Make two equal rectangular, solid blocks out of the same
material. The blocks should have the dimensions 15 × 15 × 20
centimeters. In each earthquake trial, the blocks will be stacked in the
same way but placed on different foundation materials. In the first
trial, put marbles or ball bearings in a shallow box and place the
structure on top of the marbles. In trial 2, replace the marbles with
several short wooden dowels or round pencils. In trial 3, use a large
sponge. (You can try other foundation materials, such as sand or
Tefloncoated cooking sheets.)

Predict which structure has the best chance of withstanding an earthquake and explain why.

Place each structure on the earthquake generator and simulate an earthquake by shaking the generator.

Observe which structure survived the earthquake the best.

Write your conclusion and revise your original explanation if you disproved your prediction.

7. 
After students have completed
their experiments, have students come back together and share their
results. Then assign the TakeHome Activity Sheet: Create Your Own
EarthquakeProof Building. Based on the results of the four experiments,
ask each student to construct a tower with three stackable rectangles
that would have the best chance of surviving an earthquake. Then have
students write a paragraph explaining why their structure is earthquake
proof. 
8. 
During the next class period,
have students share their “ideal building” concepts. If time permits,
select a couple of “ideal” structures and test them out on the
earthquake generator. Can the structures withstand the simulated
earthquake? 

Tidak ada komentar:
Poskan Komentar