- #1

siddharth23

- 249

- 26

How can I calculate the vacuum created and the density of materials that it can suck in?

Thanks

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- Thread starter siddharth23
- Start date

- #1

siddharth23

- 249

- 26

How can I calculate the vacuum created and the density of materials that it can suck in?

Thanks

- #2

Aero51

- 546

- 10

http://en.wikipedia.org/wiki/Bernoulli's_principle

- #3

siddharth23

- 249

- 26

Righto. But the pressure gradient will determine the force. And how do I determine the gradient?

- #4

UltrafastPED

Science Advisor

Gold Member

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1. The fan moves so many cubic liters of air per second (or CFM if you must)- call this Q.

2. The geometry of the tubing provides a cross section which all of the incoming air must pass - you are interested in the "intake port" where the work is being done - label this cross sectional area A.

3. Now you need a formula which will provide the pressure - the simplest is the the Bernoulli equation: http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

4. The particles of dust and what not are now exposed to the pressure differential computed in step 3. If you know the size and mass of a particle you can calculate:

a. the gravitational force holding it down F=mg

b. the pressure force pulling it up P/cross section of size = lift force

If you only know the density of the stuff on the floor you will have to assume some geometry - this being a physics forum we will take the default and use "spherical cows": thus the density is m/(volume of sphere) and the cross sectional area is the area of circle of the same radius as the sphere.

You should be able to work out the rest, detail by detail.

For a real vacuum cleaner there are more considerations; see http://home.howstuffworks.com/vacuum-cleaner.htm for a good start.

- #5

Aero51

- 546

- 10

- #6

256bits

Gold Member

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Or is it the size of material and density that the vacuum can suck up. Certainly any vacuum that could suck up iron fillings might have some trouble with half inch or larger ball bearings even though the density is the same.

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