[geeks] Diesel test revisted

[Shannon Hendrix]

Nuts, I messed up my reply to the diesel aptitude test.

I said I got them all right, but I actually scored 82 percent.   
However, I reviewed the question and checked them against my physics  
book, and my score should have been almost perfect.

Several of the questions are either plain wrong, or worded badly.

No test is perfect, but I like the mental work in reviewing ones like  
this, so:

Question 7: I think they have this wrong.  They say that D is reverse  
and A is reduction.

I disagree, depending on the overall design of a transmission.  The  
problem with this question is that it really can't be answered.  Gear  
A reverses direction and does reduction.  Whether or not it results  
in reverse travel depends on the rest of the system.

I'm not sure how they expected those questions to be answered without  
more information.

Question 8: They claim answer two, but I submit answer three is  
correct.  They use the terms turn and rotate as if they meant  
different things, but they don't.  I assumed rotate referred to the  
set of planet gears, and turn referred to the individual gears.  I  
actually thought about which way they meant, and there really isn't  
enough information to determine that, so I just picked one.

They should have clarified the question so it was obvious which  
direction referred to individual gears and which referred to the set  
of them.

Question 38: They say the fan will rotate in the same direction.  You  
could answer either way, depending on how you visualize the fans when  
answering the question.  The question didn't specify if the answer  
should be relative to their positions, or relative to the fans  
themselves.  I answered thinking of the latter because of how other  
questions in the test were worded.

Question 48: They say the air enters the cylinder due to atmospheric  
pressure.

Incorrect.  Pressure is a factor, not a cause.  Try putting a  
pressure neutral cylinder in an engine and see how well it runs.

In just about any modern engine, back pressure is far greater than  
atmospheric pressure, and the engine would simply not run at all if  
you only relied on the cylinder matching air pressure, effectively  
just "getting out of the way".

Now, I'll carefully avoid talking about the ones that I really did  
screw up on... :)

Oh, what the hell: two pulley questions, and the pipe pressure question.

And, um... the balloon one.  Yeah, really.  I missed the easiest one  
on the whole test.

What sucks about missing those is I knew the answer to them, I just  
didn't pay enough attention to the question.

Definitely don't get in a hurry taking this test.

Anyway, despite what I said above, this is a pretty good test.  I  
think it needs some refinement as I mention above, but it is one of  
the better ones I've seen.  Effectively presented too.

-- 
"Where some they sell their dreams for small desires."