My PBL Project

MATERIALS: Square metal plate, silica supply, shaker, large plastic container (to hold silica that falls), function generator, sine wave generator, mechanical vibrator, power supply for sine wave generator or function generator, two red I/O cables

INTRODUCTION: Question: How does silica (sand) react to different frequencies; what shapes does it form when it vibrates at a certain frequency? I will be changing the amplitude and frequency of a function generator or a sine wave generator to change the output of a mechanical vibrator. This will make the plate vibrate and cause the silica to vibrate too, forming shapes.

PROCEDURE:

1. Fill the shaker with silica from your supply.
2. Plug in the power supply of the sine wave generator or function generator.
3. Connect the output of the sine wave generator or function generator to the input of the mechanical vibrator using the two I/O cables
4. Unlock the mechanical vibrator
5. Insert the square metal plate into the mechanical vibrator and lock it
6. Turn on the sine wave generator/function generator
7. Change frequency and amplitude as needed to create patterns
8. Disassemble and pack up when finished

SCIENTIFIC PRINCIPLE: Every object has multiple natural frequencies that it can vibrate at. When the mechanical vibrator vibrates at the same frequency as one of the plate's natural frequencies, then a standing wave is formed between the two waves, because they cancel each other out. There will be some areas called nodes that do not vibrate, and the vibrating areas will push the sand onto these nodes. The sand forms the same patterns as the nodes and allows us to see what shape they are.

SAFETY: Silica is harmful and should not be ingested, inhaled, or allowed to come in contact with sensitive areas of the body such as the eye. It can cause silicosis in the lungs and has been shown to cause cancer.

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