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Terminal Velocity - Stacked Coffee Filters
Purpose
To illustrate terminal velocity quantitatively.
Equipment
Coffee filters, meter stick.
Suggestions
Practice.
Images
Description
Stacks of different numbers of coffee filters are dropped from various heights. The viscous force is proportional to the square of the velocity, so the terminal velocity is proportional to the square root of the number of filters in the stack. A stack of four filters will have a terminal velocity twice that of a single filter; the stack of four will therefore take the same time to fall two meters that a single filter takes to fall one meter. A stack of two filters will fall 1.4 meters in the time a single filter falls one meter, as is being demonstrated by the gentleman in the photograph.
References
Byron L. Coulter and Carl G. Adler, Can a body pass a body falling through the air?, AJP 47, 841-846 (1979). Neil M. Shea, Terminal Speed and Atmospheric Density, TPT 31, 176 (1993).
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See pagesc1. center of mass motion
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See pagesc3. first law of motion
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See pagesc4. second law of motion
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See pagesc5. third law of motion
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See pagesc6. friction
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See pagesc7. collisions
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See pagesc8. mechanical energy & power
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See pagesc1. center of mass motion
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See pagesc3. first law of motion
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See pagesc4. second law of motion
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See pagesc5. third law of motion
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See pagesc6. friction
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See pagesc7. collisions
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See pagesc8. mechanical energy & power