What's your answer to this question??

[fasterpatrick]

Some where there are physics teachers crying.

[lineslinger]

Two.
Pull the plug on a cylinder and put your thumb over it, then crank the engine over.
Suction occurs on the intake stroke even though the intake valve is open. The air fuel mixture is displacing the space left by the very sudden violently ever increasing size of the void created on the intake stroke.
The mixture doesn't just "drift" into the cylinder from atmospheric pressure.

[Naumoff]

The answer is three.

And cold doesn't exist. It is only the absents of heat/energy.

[Barnsnake]

Right. There's no dark, there's no cold, and there's no suction. Those are only the reduction in the level of something that is real.
In the case of the cylinder, the piston movement reduces the internal pressure, allowing the real actor, atmospheric pressure, to flow into the cylinder.

[lineslinger]

Originally Posted by Naumoff

The answer is three.

And cold doesn't exist. It is only the absents of heat/energy.

Tony, I'm with you on "cold", but..
Are you telling me that the downstroke of the piston doesn't create a vacuum? That no suction is present?
That with the sudden drop of the piston there is no reactive effect to fill the void that is created?
The intake valve does not open at the bottom of the stroke, it opens before the bottom of the stroke.

[fasterpatrick]

vac·u·um ; an enclosed space from which matter, esp. air, has been partially removed so that the matter or gas remaining in the space exerts less pressure than the atmosphere
Dictionary.com Unabridged (v 1.1)
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2006.
There is no suck; Patrick

[lineslinger]

I am talking about suction, not vacuum. I shouldn't have used the word vacuum earlier.
Suction occurs when a low pressure area is created in relation to ambient pressure.
The piston drops faster than the ambient pressure can displace the low pressure area created.
Suction.

[Naumoff]

Originally Posted by lineslinger

Tony, I'm with you on "cold", but..
Are you telling me that the downstroke of the piston doesn't create a vacuum? That no suction is present?
That with the sudden drop of the piston there is no reactive effect to fill the void that is created?
The intake valve does not open at the bottom of the stroke, it opens before the bottom of the stroke.

At sea level there is atmospheric pressure or psia(absolute) of 14.7.
When you see a Gage reading zero that is not true pressure that is Gage pressure. There is pressure pushing down on everything all the time.

The air/fuel mixture needs time to move into the cylinder. Opening on the down stroke gives it time to move in nice and smooth. As the piston goes down it does not let the air underneath it fill the cylinder so the valve opening lets the pressure in the top of the carburetor go through it and into the cylinder.
Nature is only trying to maintain balance.

Water seeks its own level.
Stick your finger over a straw and plunge it into a glass of water. What happens? the water does not go up the straw. Why? Are you pushing pressure in the straw or are you pulling a vacuum on the top of the glass?
If I haven't confused you enough keep asking question. I will get you there sooner or later.

[Naumoff]

Originally Posted by lineslinger

I am talking about suction, not vacuum. I shouldn't have used the word vacuum earlier.
Suction occurs when a low pressure area is created in relation to ambient pressure.
The piston drops faster than the ambient pressure can displace the low pressure area created.
Suction.

Suction is the creation of a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Physicists consider the notion of "suction" to be specious, since vacuums do not innately attract matter. Dust being "sucked" into a vacuum cleaner is actually being pushed in by the higher pressure air on the outside of the cleaner.

Higher pressure of surrounding air can push matter into a vacuum but a vacuum cannot attract matter

This is all just a matter of physics.
# 3 is the correct answer. No matter what you think just except it.

[lineslinger]

Okay, I'm still with you.
But does not the inlet size of the orifice through which the air passes, dictate the speed at which the ambient pressure may equalize in the ever increasing size of the chamber?
If the size of the chamber is increasing faster than than the ambient pressure can displace it..are you not, at least by definition, creating suction?

[Naumoff]

Suction is the creation of a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Physicists consider the notion of "suction" to be specious, since vacuums do not innately attract matter. Dust being "sucked" into a vacuum cleaner is actually being pushed in by the higher pressure air on the outside of the cleaner.

Higher pressure of surrounding air can push matter into a vacuum but a vacuum cannot attract matter

It is specious.

[Barnsnake]

In the everyday human-perceived world, darkness, cold, and suction are things that we can relate to, but in the science of physics they are not sources of action.
Yes, "suction" can be caused by externally acting on a system, but it is the higher pressure elsewhere that causes matter to move. In effect, the crankshaft turning, pulling on the rod, and lowering the piston, simply creates the opportunity for the atmospheric pressure to flow into the cylinder.

[lineslinger]

So this is as much about interpretation of common terminology as opposed to a more technical/scientific explanation, but, I do get it.
I'm off to see if I can find some other interpretation of suction around here.
G'night gents.

[Excaliber]

It's number 3, stick a fork in it! And there will be LESS pressure pushing the air in as you go higher in elevation. Go high enough and the piston won't 'suck', it won't create a 'vacuum', because there is no EXTERNAL pressure in space. And hopefully the fuel makes a 'phase change' from a liquid to a gas, due in part to the low pressure it is subjected to during intake.

By the way, you can't hear a 'blower' scream in space...

Similiar questions:
Is a plane 'pushed' up or 'lifted' up? Are F1 cars 'pushed down' by the air foils or sucked down by a low pressure zone beneath the air foil?

[Naumoff]

Originally Posted by lineslinger

So this is as much about interpretation of common terminology as opposed to a more technical/scientific explanation, but, I do get it.
I'm off to see if I can find some other interpretation of suction around here.
G'night gents.

Mark, Here's a start.


Don't be a sucker.
meaning be deceived

suck
verb

to be inadequate, displeasing, or of poor quality.
Final exams suck.

[mr bruce]

http://www.keveney.com/otto.html

[joey_hv]

geeez, if this one threw you guys for a spin, try figuring it out at -65fsw...lol
daily stuff for my peer group..

[lineslinger]

So Joey,
At 26 fathoms are you sucking air or is the ambient pressure in your helmet/suit? forcing it in?

[lineslinger]

Originally Posted by Naumoff

Mark, Here's a start.


Don't be a sucker.
meaning be deceived

suck
verb

to be inadequate, displeasing, or of poor quality.
Final exams suck.

Tony, I was thinking more along the lines of suction in a female sense.

[CBattaglia]

My .02 The suction creates the low pressure situation. So both answers are correct. Low pressure is the end result you are looking for.



I hate multiple choice questions!!