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Page 3 of 10
1. simple experiment: crater shapes
Materials:
1. A shallow box or other container. A plastic or cardboard container, the size of A4 paper or larger is fine.
2. Surface material. This can be wheat flour, fine sand or equivalent dry granular medium. (You will later experiment with wet and more or less fluid materials, such as wet sand, wet plaster of Paris.)
3. Coloured medium to coat the surface. This can be cocoa powder, powdered paint, or table salt tinted with food colour. This makes it easier to identify and measure the impact craters.
4. Objects to use as projectiles. You can use a variety of objects, balls of different sizes of wood, styrofoam, steel, rocks, marbles.You may also experiment also with softer objects like blobs of clay or wet sand, water drops (Exp. 1.7).
5. Optional: grab, pair of tweezers, or a magnet on a string, which you need to retrieve your projectile without disturbing the surface medium.
6. Optional: newspaper or plastic sheet to keep the floor clean.
Experiment 1:
Fill the container with the surface medium (flour, sand etc.), using a sieve to distribute it evenly (not with wet sand or plaster of Paris, of course).
Sprinkle the surface lightly with the coloured medium (e.g. cocoa powder) with the use of a fine sieve.
| Before you start, don’t forget to write down the problem (research
question) you are going to explore, as well as your hypothesis
(assumption). |
Drop the projectile from different heights: knee-high, shoulder-high and as high as you can reach. Try to drop it on an undisturbed part of surface.
Carefully study the shapes of your first impact craters. Make sketches/photos.
Do all have the same shapes? If not, can you think of a reason?
Note also the material that has been thrown out of the crater, the ejecta. Count the number of ejecta rays and measure their lengths.
Do you find any relation between drop height and number or length of the rays?
Can you explain it?
After a few experiments, you will need to level the surface again and sprinkle a fresh layer of coloured medium on it.
Conclusions:
Write down your conclusions. Do they agree with what you expected? Do not be afraid that you made a mistake if they do not. This is how science progresses.
You have learned something new!
Now for the next experiment
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