Mechanical Aptitude Test

[agjohn02]

that piston one is BS. Would atmospheric pressure be sufficient to push the piston down and fill the cylinder with air if the crank didn't pull it down? Fawk no, the crank is pulling the piston down, creating a void and vacuum which pulls air in.

and thats why you are not an engineer. so, does it create more of a vacuum when you put boost on it?

[robertf03]

it pushes the piston down and makes the motor spin

[fbronco86]

and thats why you are not an engineer. so, does it create more of a vacuum when you put boost on it?

And you are

[DRAGOONRANCH]

And you are

why, because he sucks?!?!

[DRAGOONRANCH]

oops,

[agjohn02]

And you are

as long as you dont count being able to do FEA by hand and matlab, yeah, i think so. i really suck at the academia way of doing FEA, never try it. just learn the software. speaking of which, i gotta go study.

[agjohn02]

on the gears i see what your saying about reverse and direct because technically the direct one is reversing the direction. however, 'D' is definitely not a direct drive.

yeah, i had the same logic and had them arranged that way, but for some reason i outsmarted myself and chaged the answer.

C- 1:1 but reverses direction
D- 2:1 with same direction

its a toss up as to which one you pick, with an edge on C being the direct if you dont sit and think about it too long.

[agjohn02]

it pushes the piston down and makes the motor spin

it puts the lotion on its skin or else it gets the hose again?

[uglyota]

If there was no atmospheric pressure, then it would stay a void.

no, if there was no atmosphere it would stay a void because it would already be a vacuum, but if the atmospheric pressure was 0 and all of a sudden the volume of the cylinder got bigger (by the piston going down), the pressure inside the cylinder becomes negative, ie vacuum, and air from outside rushes in to fill the vacuum.

[agjohn02]

[agjohn02]

i went back and looked at the question. its misleading yes, but if you read all the answers, the correct one should be obvious.

here you go eric, from your favorite source of information:

"On the first stroke (intake/induction) of the piston, as the piston descends it reduces the pressure in the cylinder, a mixture of fuel and air is forced, by at least atmospheric pressure, into the cylinder through the intake (inlet) port."

[uglyota]

I don't care what wikipedia says. The air is not forced in by atmospheric pressure. It is forced in by the vacuum that is the difference between the pressure inside the cylinder and the pressure outside the cylinder, which may be atmospheric pressure or it may be higher, it doesn't matter. The air would not be moving if the piston hadn't gone down, increasing the volume of the cylinder and creating a vacuum. PV/T=PV/T

[BMFScout]

Pv=nrt what?

[jerryg79]

i=prt!

[agjohn02]

Pv=nrt what?

i was gonna call him on that but if you rearrange the equation and take some stuff out, it right. its not a good argument though. im just saying that 3=3 and 2=2.