What's your mechanical aptitude?
 

http://www.forddoctorsdts.com/quizze...alAptitude.php

Passing grade is 80%. I scored 88.

Pretty cool---I got a 74 drunk.

I got an 84, I rushed through it pretty quickly.

and some of the stuff definently depends on prior knowledge... wasnt sure on all the symbols for the electrical diagram. and some of it was just vocabulary.

82%...........but they don't tell what I missed???...xoxoxoo

300 points - 60%

Not very surprising.

I also wish I knew what I got wrong ...my score was 82 but considering that I have a BSME and I'm Vice President of Engineering, that seems like a bad score for me. A demotion might be in order.

86%. Not bad, for a high school drop-out.

I think that's kind of the point.

68% failed lol. I went super fast.

82% with a BSME as well. Some of the questions I felt were ambiguous, maybe I just needed to slow down a bit.

from the paragraph before the test

"Mechanical aptitude tests do not measure what you know, but rather your ability to learn about and understand mechanical concepts and how things work."

My mistake. Seems my passing grade is paired with another typically male trait - I didn't read the directions.

Even still, I figured the electrical diagrams to be the hardest part to decipher overall and even those seem pretty self-evident to me; but then, I'm biased, as I learned how to draw a wiring diagram when I was 11.

86% Kind of surprising, for whatever reason I tend not to score very well on these kind of tests.

I got 98%...forgot that suction doesn't exist, and that atmospheric pressure 'pushed' the air in. Lame.

Oh, and you can review your scores by clicking the magnifying glass when you're done.

I got the same question wrong Twisted. But I disagree. as the piston moved downward, it creates a vacuum or "suction" on the opening where the valve is. That is why when an engine is running, it has vacuum in the intake, that is used for brake boost and any other vacuum operated device on the car. Suction DOES exist. But still an interesting test.

the electrical questions threw me. 74%, I guess I should go be a psychologist...

Fun Quiz! I got a passing grade of 86% -

Missed: 3, 11, 12, 38, 41, 48, 50

Of the ones I missed:
3: I forgot to count the teeth on the gears...figured it out on the next few questions.

11: just mis-read the worm gear.

12: mis-clicked

38: oops

41: had NO idea about this one.

50 DEFINITELY requires prior knowledge of what all of those shafts are...

I missed the automatic transmission one because I read too fast and misinterpreted what they meant by the gears "rotating" and "turning." If they said "the assembly turns" and "each gear rotates," it would be less ambiguous. I just clicked the wrong answer on 9. Number 45 is ambiguous because they should have specified that they're talking about the force acting on the balloon, not "pressure outside of the balloon," which will be equal if they're in the same space. In number 26, I tripped up by thinking of the circuit as a series-parallel combination rather than a series with a bypass for one component (I was thinking of the switch as if it were a resistor in parallel with the middle bulb.) Then I fell for the good old suction trick question.

If the questions that I misinterpreted had been clearer and I had clicked the right button for 9, I would have had a 96, but I got a 90.
Scientifically, there is no such thing as suction, just areas of higher and lower pressure. I didn't read all the answers before clicking.

No, they're right, the piston moving down produces a low pressure area that is filled by the atmospheric pressure pushing air in. It seems like a trivial distinction, but it is helpful to know an NA car recieves air at 14PSI when you're doing turbo or supercharger calculations (at a very very crude level, 14psi = twice as much air = twice as much horsepower, allowing for proper support mods.)

82%. I missed stuff on the electrical diagrams and a couple on pulleys and fulcrums.... but I studied English in college. I guess I'm just glad to have passed.

Sorry, but for the record I will just have to disagree with you on this one. I see the point you are trying to make, but in a real world situation, there is "14psi" of normal atmospheric pressure at all times at sea level. so a moving piston would create a vacuum based on the principal of air flow through a restriction (i.e. the open valve) If you were to actually connect a vacuum/pressure gauge to the cylinder you would see the fluctuations of vacuum (and pressure when on compression stroke). We did this experiment many years ago in our physics class when I was getting my degree in automotive technology. The question we had was based on a naturally aspirated engine, turning at normal cranking RPM of a standard V-8 engine. The solution was that since the movement of air at atmospheric pressure was too slow, a vacuum HAD to be introduced by the piston, otherwise the cylinder could not fill up fast enough to produce proper combustion. (based on volume of air that can be moved at atmospheric pressure, v/s volume of air that can be moved under vacuum)

I got an 86%. Reviewing the test I should have got a 92%. Three stupid mistakes where I didnt pay attention, the only four I genuinely did not know were the questions about the pulleys and force. Dumb on my part.

And yes I agree question 48 was stupid. I think it really is both. Without the low pressure area created by the piston there would not be a place for the atmospheric pressure to go. But the atmospheric pressure does push it in, and the amount of atmospheric pressure does affect how much air goes in. If it was just the piston suction alone then I would think a naturally aspirated engine would make the same power regardless of altitude. Yet an engine makes 18% less power here in Denver than at sea level.

I got too bored with it and stopped at 26

66% it's been very very long since i had any reviews on mechanical stuff. oh well!

I got a 68%. I was destroyed by the electrical and engine-specific questions.

Well, for the record, are you trying to say that the test and I are both wrong?

I'm confused (but curious) by your description of your experiment...any more details on exactly what you were trying to prove?

There are two measurements of pressure--gauge pressure, which compares something to atmospheric, and absolute pressure, which is the actual scientific pressure present. If you had some way of measuring absolute pressure on a cycling cylinder, it would have just read less than 14psi on the down stroke, higher (atmospheric x the compression ratio, usually about 9:1, so 126psi-ish) on the upstroke, and extremely high during combustion.

I'm not sure what you mean exactly by "The solution was that since the movement of air at atmospheric pressure was too slow", as air that is at atmospheric pressure won't move at all! It won't move unless there is a pressure difference, such as the one set up by the low pressure volume created by a dropping piston.

In the real world, when you are talking about moving gasses, it isn't a matter of opinion--there is no such thing as suction or vacuum. These are both laymans terms to describe the observed effects of a pressure differential. When speaking scientifically, forces from pressure differences are always a push, never a pull. (and yes, dirty jokes about the fact that therefore nothing can ever be sucked abound...luckily they can still be blown :thumbsup: )

Our two (real) choices were:
In a NA engine, air enters the cylinder...
From suction caused by the piston going down
From atmospheric pressure pushing it in

Since suction doesn't exist, then the answer becomes obvious. The expanded volume of the cylinder created by the descending piston temporarily creates a low pressure volume inside the cylinder, and atmospheric pressure pushes new air in. If you still don't agree, think about how the situation would change if you changed atmospheric pressure. Bring it to the top of a mountain where there's less air pressure? Guess what, less air gets pushed into the motor, and you have less power.

I have a feeling that you and I are just using different words to describe what's happening, however in this specific case, the question was one of definition, so which definition is more accurate is what it has to come down to. My gas dynamics prof would be horrified if I ever put "suction caused by the piston pulls air through the valve" on any of my tests.

OK, lets see if I can clairify my opinion:

What I am saying is that in a NA engine, where no movement of the piston is present, and the intake valve is open, we have a ballance of pressure on both sides(14.7 psi at sea level). when the piston moves downward, it creates a "negative pressure" or vacuum in laymans terms. This difference in pressure causes the outside air to be drawn in. So in MY opinion, it is the creation of "negative pressure" that causes the air to move, not just the static pressure of atmospheric pressure that moves itself. This leads me to the hypothosis that it is the VACUUM that is the action, and the air movement is the reaction.

As far as our experiment, we were using an absolute pressure gauge, and slow motion video of the needle. of course we never reached lower that 7 psi of "negative pressure", as those who know much about science, it is near impossible to actually attain 0 psi in most scientific experiments that are done in a classroom lab. the lowest we ever did using a pump was 4 psi before the cylinder cracked.(we were using a glass cylinder with a small amount of mercury in the bottom to see if we could detect any "movement")

The reason you have less power in a NA engine as nothing to do DIRECTLY with the atmospheric pressure, but the DENSITY of the air that is draw into the engine. Yes A.P. is lower in denver, but the REASON it is lower is that the air in Denver is less dense. DENSITY of the air is what makes the difference in engine power, that is why in racing, colder weather is prefered, because colder air is more dense, and this gives the engines more power.

If you were getting a negative reading, you weren't measuring absolute pressure. If you had been, there wouldn't be any negative pressure (there's no such thing), there would have just been some positive pressure lower than atmospheric. This isn't an action/reaction situation, it's a definition of terms. The piston creates a low pressure area that the atmospheric pressure fills. I'm not trying to tell you you don't undnerstand an engine--For most applications, your understanding is close enough to correct as to not matter. What I'm saying is that if it gets down to the brass tacks of the definition, like it did on this test, it's the pressure that does it.

I guess you still werent quite understanding what I am trying to say. I am using the term "negative pressure" as any pressure below standard atmospheric pressure...i.e. anything below 14.7 psi at sea level. I still just personally disagree with you. Just to make sure, I called my old instructor and asked him about it. and he said TECHNICALLY both explanations are correct, it just depends on how you look at it. after we talked he took the test (i sent him the link) and he got a 100% (go figure) but he DID agree that in the scientific word, either answer would be correct, so really you and I are BOTH right! Thanx for the interesting conversation.

My middle school and high school science teachers spent seven years hammering into my head the fact that "suction" does not exist, only areas of higher and lower pressure. Suction is a layman's term, not a scientific term and therefore not an acceptable answer on a test that measures scientific aptitude.

OK I will just stop here. i guess i can't get ANYONE to understand my point. I am NOT SAYING suction exists. i DO understand that it is merely a difference in pressures. but still, the question CAN and obviously HAS been in the way this test was set up, misunderstood. I think the question is a manner of interpretation. either way, the test is interesting, and I am happy that I only missed one question.

..

no surprise, i failed with a 68%

actually, i'm surprised i got a 68%

all i really know is "lefty loosy, righty tighty"

cool test, thanks for posting that

62%

Not surprised. I did get the electrical stuff right. My dad is an electrical engineer.

I was always under the impression that suction fit this definition:
So i'm perplexed when i hear that suction doesn't really exist because what's really going on is that fluids flow down pressure differential. To me it sounds similar to making a claim that frictional forces don't exist because what's really going on is shear stress due to the breaking of the microwelds that form at asperities between two materials in contact. We generalize it and call it friction because its convenient. How is suction different? Going a step further, you could claim that the "pressure gradient" explanation is wrong too, because pressure doesn't actually exist- it's just a macroscopic approximation for interactions between different particles.

The test was poorly worded, it happens.

92% The test could use a re-writing for clarity.

370 points for a 74%.
Considering I dropped out in 10th grade and never took a math or science class in my life, I can live with that.