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ANSWERED on Wed 4 Jun 2008 - 9:42 am UTC by sublime1

Question: How much force is generated by a sneeze? How could I measure that force?

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Sun 1 Jun 2008 - 11:29 pm UTC

Question

happyengineer
Customer

How many pounds/newtons of force does an average sneeze generate?

For instance, if someone were to sneeze onto a windmill with 100% efficiency, how much energy would be generated? If someone sat at the back of a blimp and sneezed all day, how fast could they get the blimp moving on a calm day for a given blimp mass?

You don't need to answer the specific windmill or blimp questions. Just give me the amount of actual force generated and I can calculate whatever I need.

Presumably this force would vary somewhat between individuals, but there must be a rough range that sneeze force falls into.

If no one knows, is there some reasonable way in which I could measure it myself? I could put some pepper up my nose and then sneeze onto/into a measurement device of some sort.

 
 

Mon 2 Jun 2008 - 2:40 am UTC

Uclue Researcher Request for clarification

John E
Researcher

Hi happy...

The speed of a sneeze varies on different websites, from about 40 mph up to 167 mph, which many pages agree on, though this tells you little about the force involved.

A Newton is a unit of force equal to the force that imparts an acceleration of 1 m/sec/sec to a mass of 1 kilogram (1 N = 1 kg · m/s2).

According to the hypertextbook, a sneeze can be measured as producing 2.9 Gs. Believe it or not, cough produces more, at 3.5 Gs:
http://hypertextbook.com/physics/mechanics/acceleration/

The G, or unit of acceleration due to gravity is g = 9.80665 m/s2

So 2.9 Gs = 28.439285 m/s2

So you have the acceleration of a sneeze, but to convert it to Newtons or any other measure of force, you would need to measure how much mass is being accelerated by the sneeze. Since it's just a certain volume of air and particulate effluvia, the mass would be rather small.

If a sneeze is 2.9 Gs, it would have to accelerate a mass of 35.1626280 grams or 1.2403252 ounces of matter to equal the force of 1 Newton.

That's all I've got. Let me know where this takes you...

sublime1

 

Mon 2 Jun 2008 - 2:53 am UTC

Uclue Researcher Request for clarification

John E
Researcher

P.S.

About the only way I can think of to measure the actual force would be to, say, focus a sneeze on a light object like a ping pong ball and find a way to measure its acceleration (not just its speed). This would require some kind of accelerometer, or device to measure acceleration. I'm fairly sure there's a way to do this with a digital camera, but that's another question entirely.

 

Mon 2 Jun 2008 - 2:55 am UTC

Uclue Researcher Request for clarification

David Sarokin
Researcher

I'll add something to John's information.  I'm not confident enough in my physics to put together an answer, but I think all the necessary raw data is there.

According to this little snippet from the medical literature:

http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GGIH_enUS242US242&q=%22duration+of+sneezing+is+1+s+with+the+volume+

a sneeze lasts a second, and forces out air (and gunk) at 250 L/min (or 4.17 L/sec). 

The density of air is 1.3 g/L:

http://hypertextbook.com/facts/2000/RachelChu.shtml

A sneeze is presumably somewhat more dense due to all the, er, stuff. 

So...a sneeze accelerates air from about 0 to 100 mph in a second, expelling about 20 g of matter in the process.

And that should do the trick, n'est ce pas?

 

Mon 2 Jun 2008 - 2:57 am UTC

Uclue Researcher Request for clarification

David Sarokin
Researcher

Forget to mention, there are devices to measure amount and rate of exhalation, though I don't know if they are calibrated for sneezes. 

Any doctor's office should have one.  Here's a bit on how they work:

http://www.wipo.int/pctdb/en/wo.jsp?IA=WO1996037147&wo=1996037147&DISPLAY=DESC
"Peak expiratory flow rate (PEFR) is a measure of lung function of a person which can be easily and accurately determined by several devices....They vary in portability, graduation and cost and work, essentially, on two different principles. The first involves the displacement of a spring loaded piston, the total displacement of which depends on both the pressure arising from the generated flow and the area of a vent located behind the piston. The second class of devices utilises whistles or reeds that are normally threshold-activated in order to register PEFR."

 

Mon 2 Jun 2008 - 5:54 am UTC

Question clarification

happyengineer
Customer

Ok, let's try to apply that to the blimp example.

B = blimp mass (in kg)
F = force generated by sneeze = 28.439285 kg*m/s^2
F = Ba = 28.439285 kg*m/s^2

a = 28.439285 / B  m/s^2

So, if we have two people on the blimp alternating sneezes constantly then we'll end up accelerating at a rate of "a" subtracting out the drag that the atmosphere is putting on the blimp.

Is that correct? If so then that's exactly what I needed.


Out of curiosity, I took david's numbers and tried to derive sublime's numbers. Here is what I got:

d = air density = 1.3 g/L = 1.3 kg / m^3
r * d = 0.005421 kg / s
N = puckered open mouth area
F = r * d / N = 0.005421 / N

I don't know what the area is of a puckered mouth, so I just plugged in david's F=28.439285 and got N=1.90616607 cm^2.

I think that 2 cm^2 is probably a reasonable area for a puckered mouth during a sneeze, so I guess the numbers check out!

 

Mon 2 Jun 2008 - 9:07 am UTC

Uclue Researcher Comment

Roger Browne
Researcher

Hi happyengineer,

One complication with sneeze-power is that the person's body will impart an acceleration equal and opposite to that of the expelled air.

A possible variation is to have the blimp powered by breathing alone. Each passenger would breathe through a facemask connected to a valve and some tubing. Breathing in would take in air from the tube connected to the front of the blimp, and breathing out would expel the air to the rear of the blimp.

The breath-power will be much less than the sneeze-power, but it should be sustainable for long journeys (provided headwinds can be avoided).

Regards,
eiffel

 

Mon 2 Jun 2008 - 10:02 am UTC

Comment

myoarin
User

What about finding a surface with minimal friction  - maybe a chair mounted on iceskates on a rink.  The coefficient(?) of friction for the person and chair can probably be measured.  Set him down and wait. ("Him", because ladies' dainty sneezes won't be so impressive.) 

You will need to train him not to make the usual body movements of a person sneezing  - drawing back and then jerking forward, may have to strap him firmly to the chair with a racing car seat belt.

Problem: sitting, waiting for the sneezes will melt the ice a bit at the contact points unless the ice is very cold.  Solution, find a large packinghouse freezer and flood part of the floor.  At -20°C, this shouldn't be problem.

And wait ...  Maybe some freshly, finely ground paper would help.

If this can be set up, it has the advantage that vageries of measuring the force after it leaves the person's mouth should be eliminated  - I think.
One would just have to measure the distance the chair moves and do the calculations.


Does the area of the mouth matter?  
I'd have thought that the best results would be achieved with a wide open mouth, nose held closed, so that the full force from the sneeze is only constrained by the throat and all comes out in one direction.

I have to question David's 20g of material  - about a wine glass of water.

Myo

 

Wed 4 Jun 2008 - 6:02 am UTC

Uclue Researcher Request for clarification

John E
Researcher

happyengineer...

Have we satisfied your interests with our responses? If so, please pick a researcher to post a formal answer.

 

Wed 4 Jun 2008 - 6:38 am UTC

Comment

probo
User

Myomyo suggested:

'Maybe some freshly, finely ground paper would help.'

I suggest that some freshly, finely ground PEPPER would be more likely to induce a sneeze.

Bryo

 

Wed 4 Jun 2008 - 9:28 am UTC

Question clarification

happyengineer
Customer

sublime1, you posted first with the data I needed, so I guess you get it.

 

Wed 4 Jun 2008 - 9:42 am UTC

Uclue Researcher Answer

John E
Researcher

happyengineer...

Thanks for acknowledging my efforts as an acceptable answer. I'll repeat them here for the sake of future readers:

---

The speed of a sneeze varies on different websites, from about 40 mph up
to 167 mph, which many pages agree on, though this tells you little about
the force involved.

A Newton is a unit of force equal to the force that imparts an
acceleration of 1 m/sec/sec to a mass of 1 kilogram (1 N = 1 kg · m/s2).

According to the hypertextbook, a sneeze can be measured as producing 2.9
Gs. Believe it or not, a cough produces more, at 3.5 Gs:
http://hypertextbook.com/physics/mechanics/acceleration/

The G, or unit of acceleration due to gravity is g = 9.80665 m/s2

So 2.9 Gs = 28.439285 m/s2

So you have the acceleration of a sneeze, but to convert it to Newtons or
any other measure of force, you would need to measure how much mass is
being accelerated by the sneeze. Since it's just a certain volume of air
and particulate effluvia, the mass would be rather small.

If a sneeze is 2.9 Gs, it would have to accelerate a mass of 35.1626280
grams or 1.2403252 ounces of matter to equal the force of 1 Newton.

sublime1

 
 

Wed 4 Jun 2008 - 11:47 am UTC

Comment

myoarin
User

Probo,

That was my Swedish background, ;)  but still misspelled:  "papper".

But  I should have also specified black pepper.

Myo

 

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