Mechanical Aptitude Test - Page 4

redranga · 04-10-2007, 10:21 PM

Does anyone disagree with the answer that they give for question 41?

Given that force = pressure X area

wouldnt the pressure be one seventh of the 50psi applied?

They have multiplied it by seven when it shouldve been divided.

I think the correct answer would be 7.14 psi

fmc351 · 04-10-2007, 10:50 PM

Quote:

Originally Posted by police

Does anyone disagree with the answer that they give for question 41?

Given that force = pressure X area

wouldnt the pressure be one seventh of the 50psi applied?

They have multiplied it by seven when it shouldve been divided.

I think the correct answer would be 7.14 psi

If thats the question I think it was,

Did you read it as spreading the force from the small area to the larger area, because it was the other way round.

redranga · 04-10-2007, 10:56 PM

The 50 psi of force was applied to the larger area and it wanted to know what if was at the smaller area.

Its the same as the brakes on your car. You master cylinder will be about 3/4 of an inch and the piston in the caliper is about 2 inches. This multiplies the force. Im sure theyve got it all eyed.

xbgs351 · 05-10-2007, 08:16 AM

Quote:

Originally Posted by BadMac

100% agree with you.
Q26 As I stated before
Q31 is 1/5 of 300KG = 60 (not an option), weight is centred 1 segment to the left and other is centred 5 to the right. If both were at the end of their respective sides 50KG would be correct.
Q38, I had to think about it when I did it for the same reason. Had to think about what answer they would want as you can't prove them wrong.
Q48 pedantic and I can show a few definitions which would assert this is wrong (I can also show some which say its right), so badily worded question. 2 equally right answers.

Q41 is also wrong. The applied force should be in pounds not pounds per square inch as psi is a measure of pressure.

Q19 Should ask what the mechanical advantage is or what the force would be neglecting friction, as there is a lot of friction in a block and tackle.

xbgs351 · 05-10-2007, 08:24 AM

Quote:

Originally Posted by Van D

What was the answer to that? I didn't check it. I guessed A as the pressure build up from the pipe getting smaller/narrower wouldn't allow enough flow and it'd need to escape somewhere. First thought was B because the pipe was narrower and thought there'd be more pressure/speed.. But went with A... Wow i'm tired that probably didn't make sense.

The pressure drops when the pipe constricts, just like a venturi in a carby.

http://en.wikipedia.org/wiki/Venturi_effect which is derived from:http://en.wikipedia.org/wiki/Bernoulli%27s_principle which is basically just a conservation of energy equation. So basically as water passes through the venturi it has an increased velocity and the amount of energy is kept constant by a pressure drop.

Homer1 · 05-10-2007, 01:23 PM

Quote:

Originally Posted by police

Does anyone disagree with the answer that they give for question 41?

Given that force = pressure X area

wouldnt the pressure be one seventh of the 50psi applied?

They have multiplied it by seven when it shouldve been divided.

I think the correct answer would be 7.14 psi

No, a smaller surface area will exert more pressure with the same force. The simplest way to explain that would be sharp blade vs a blunt blade...which is easier to cut with using equal force with your hand?

FrogInASock · 05-10-2007, 02:07 PM

94%. Associate Diplomas in Engineering rock. What did I get wrong?
Q28 Parallel batteries, typo!
Q38 Two fans facing each other, yair, I got it wrong.
Q39 Mechanical principle used in brakes. It's friction, stoopid!

So without the typo, would have been 96%.

redranga · 05-10-2007, 06:59 PM

I went back through the test and can agree that Q41 is right.

Ill have to disagree with on your example also Homer. A knife doesnt use hydraulic multiplication to cut. It uses friction. The sharper knife has less friction than the blunt one so it cuts easier.

Have a look here: http://science.howstuffworks.com/hydraulic1.htm to understand about hydraulic multiplication.

Blue Oval Mopar Man · 05-10-2007, 07:48 PM

I got 88% so I think I got 6 wrong ! I hate wiring and electrical !

mrxy8 · 05-10-2007, 09:04 PM

98% got ha retarded #2 wrong

:

kremmen · 05-10-2007, 09:04 PM

Quote:

Originally Posted by GreenMachine

79%... But I'm a lawyer, not an engineer.

92% and probably couldn't put much of it into practice....

I'm surprised you didn't argue that 21% of the questions were incorrect then...

:

Van D · 05-10-2007, 09:11 PM

Quote:

Originally Posted by xbgs351

The pressure drops when the pipe constricts, just like a venturi in a carby.

http://en.wikipedia.org/wiki/Venturi_effect which is derived from:http://en.wikipedia.org/wiki/Bernoulli%27s_principle which is basically just a conservation of energy equation. So basically as water passes through the venturi it has an increased velocity and the amount of energy is kept constant by a pressure drop.

...

So it was A? :P

I think i've got my head around it.

BOOSTDEF · 05-10-2007, 09:44 PM

I got 80%.. Stuffed a few ratios and the suction cylinder Q.. plus a few here and there..

Im a structural engineer so Im not used to things moving ;P

XR6Dan · 05-10-2007, 10:28 PM

90% Yeh baby

Nostalgia · 05-10-2007, 10:57 PM

New apptitude test. HOW MANY OF YOU ARE LYING ABOUT YOUR SCORES ?

tapeworm · 05-10-2007, 11:11 PM

56% from my corner. Am I semi retarded

: ? lol.

blk_frmnt · 05-10-2007, 11:50 PM

80%

Haven't seen any of this since high school physics, and I was feeling pretty good about my result until I saw this:

Quote:

Originally Posted by Fantome

My 13 year old daughter did the test and got 84%. Smart girl!

EX-Y494 · 06-10-2007, 12:53 AM

88% I'm happy with that.

DDXR6T · 06-10-2007, 01:30 AM

90%, nobbad for no special education ...

prof-rabbit · 06-10-2007, 02:24 AM

I got 76% but still didn't pass, bummer.

T3man · 06-10-2007, 01:43 PM

heheheh ... 92%, I can live with that BUT, there is a trick question or two in there that are ambiguous.

Gammaboy · 06-10-2007, 01:52 PM

Did this the other day when GreenMachine emailed it to me... 100%.
Sweet. I'm smart enough to become a diesel mechanic.

blackers10 · 07-10-2007, 03:39 PM

74 percent
didnt take too much time on it

id say i got most of the ratio ones wrong(ie how much weight does B require to be moved etc

Debzilla_108 · 07-10-2007, 04:01 PM

i got 54%
im proud of my self lol i got more then half...

Perun · 07-10-2007, 05:56 PM

Quote:

Originally Posted by Yellow_Festiva

80%... yay.

Not bad for a person who dropped out of physics after 2 weeks in yr 11.

Ok, but I also taught "Simple Machines" term 2, and electronics term 3 lol.

Same score, similar situation. I bludged at the back of the classroom until the end of year 11. hehe

blownba · 07-10-2007, 05:59 PM

Quote:

Originally Posted by EX-Y494

88% I'm happy with that.

Hey EX-y494. have you noticed that the little guy in your avatar is standing infront of a clutch pressure plate????
Or did you notice and did it for a reason???

JBomb3000 · 07-10-2007, 06:00 PM

78%, I failed