~Earthquake City!~
Background
The movement of the ground during an earthquake can cause serious damage to buildings and other structures. The damage caused to a structure depends on its design, the materials used to make it, and the strength and duration of the vibrations from the earthquake. You can test different structures and materials for their ability to withstand earthquakes in your Earthquake City.
Materials
What You Need To Do...
Turn the empty box upside down. Use your pencil and ruler to draw vertical lines and horizontal lines to make a grid on the bottom of the box. Each line on the gird should be 5cm apart. Label each horizontal line A, B, C, etc. Label each vertical line 1st, 2nd, 3rd, etc. Each line is a street in Earthquake City!
1. When there is an earthquake, energy travels through the Earth and can cause damage to buildings and other structures far away. To show this, build three sugar cube skyscrapers, each five sugar cubes tall. Build the skyscrapers at the following corners: A and 1st, B and 2nd, C and 3rd.
2. Now make an earthquake by tapping with the eraser end of a pencil on the box at the corner of D and 4th. Continue tapping until at least one cube from each of the skyscrapers falls. Which skyscraper falls first? In a real earthquake, do you think more damage would happen in one place than another? Where would most of the damage happen?
3. The amount of damage caused by an earthquake depends on the strength of the earthquake and on how long it lasts. Build your three skyscrapers again in the same locations as before. See how many hard vibrations it takes to knock at least one cube from each building. Find out how many softer vibrations it takes to cause the same amount of damage.
4. Whether a building has heavy objects at the top or bottom has a lot to do with the amount of damage done during an earthquake. Build one skyscraper by stacking three sugar cubes on top of a bouillon cube. Build another by stacking a bouillon cube on top of three sugar cubes. Since the bouillon cube is heavier than the sugar cube, one building has some heavy at the bottom and the other has something heavy at the top. Place one building at the corner of A and 1st and the other at the corner of A and 3rd.
5. Create an earthquake by tapping at the corner of C and 2nd until at least one cube falls. Repeat this test three times. Be sure to tap the box the same way each time. Does the same building fall each time? Which building was more stable during the earthquake?
6. Today some skyscrapers are made more flexible so that they actually bend and sway and do not fall down as easily. Stack four or five gelatin cubes on top of each other to make a flexible building. Put it at the corner of C and 2nd, and create an earthquake at the corner of B and 4th. What happens to the skyscraper during the earthquake(before it falls)? How long do you have to tap before it falls?
7. Use the sugar cube, bouillon, and some gelatin cubes to build a complete Earthquake City! Make some buildings tall and some short. Construct buildings made from a combination of different kinds of cubes. Place them at different locations around the city. Pick a spot anywhere in the city to create an earthquake. The spot you choose is the epicenter of your earthquake. Predict which building will collapse first and which will not be affected at all. Make a table to record the structure of the building, the location of the building, the duration of the earthquake, and the epicenter (location) of the earthquake. Record your predictions, inferences, and recommendations for each test.
Source: Wonder Science, March 1992, American Chemical Society. Contributed by A. Miles and S. Vance, Rice Model Science Laboratory, Houston, TX.
