Neat mechanical aptitude test

[SVRACER01]

its wrong.

[OreoGaborio]

its wrong.

You're wrong... the worm gear is turning towards you... the threads are going right to left. the gear is turning counterclockwise.

[R1]

The one with the switch that goes parallel to the light - I answered that all three lights would go on. The current would still flow through both legs.

The path of least resistence.



No matter how you look at it electricity will travel this way. you could have 10 feet of wire between the bulb and the switch, but wire resistence is negligable. it has no effect to the high amounts of resistence the bulb would have before energizing.

This is assuming that the resistence stated in the diagram is a light bulb!

[R1]

so who else didnt pass?

[978chris]

The path of least resistance.



No matter how you look at it electricity will travel this way. you could have 10 feet of wire between the bulb and the switch, but wire resistance is negligible. it has no effect to the high amounts of resistance the bulb would have before energizing.

This is assuming that the resistance stated in the diagram is a light bulb!

fixed.

i was reading it and something kept bugging me but i wasn't sure what it was.

[R1]

fixed.

i was reading it and something kept bugging me but i wasn't sure what it was.

???????????

[Dangerz0ne]

damn. 78 and I work on mechanical equipment for a living. that's sad.

[Steve]

I got a 98 on my first try! :banana:

And the one I got wrong I actually got right, the test makers are wrong!!

Question: Rapidly compressing air and increasing its pressure does what to the temperature?

They say it increases temperature. That is wrong!

Compressing, ie decreasing volume along with increasing pressure.

According to the ideal gas law: PV=nRT

Thus increasing pressure while decreasing volume will have no effect on temperature (assumption: pressure increase and volume decrease are proportional, which I would think is a logical assumption).

Im writing an email. And that is your science geek lesson for the day

If you got that one wrong and said no effect, add 2 points to your score.

If you are compressing as in an air compressor, by pumping more air into a holding tank--volume stays the same. But if you were compressing it by applying external pressure to something like a balloon--volume would decrease. Some of the questions are too vague--especially that lever question which one would be easier to lift.

[KB]

I made it to question 10 and said fuck this!!!

KB

[SSearchVT]

The path of least resistence.



No matter how you look at it electricity will travel this way. you could have 10 feet of wire between the bulb and the switch, but wire resistence is negligable. it has no effect to the high amounts of resistence the bulb would have before energizing.

This is assuming that the resistence stated in the diagram is a light bulb!

The diagram they have is a parallel circuit:

1/R(resultant) = 1/R(switch leg)+1/R(light leg)

When the switch is closed the majority of current should flow through the switch leg (assuming small resistance in the wire and switch), but current will still flow through the light leg as well. The light won't be as bright as the others, but it will be lit.

[ZX-12R]

I don't care about you're perfect little law, try grabbing the output of a compressor & tell me how quickly you will remove your hand as it sizzles!

The ideal gas law is not the correct equation for this scenario:

http://www.nestreetriders.com/forum/425573-post28.html

[978chris]

The light won't be as bright as the others, but it will be lit.

Ok I always get confused between amperage/voltage (strength vs. capacity?) so maybe I'm using the wrong one here, but:

Doesn't the bulb lighting to any degree depend on amperage? If there isn't enough, it won't light?

No?

The drawing doesn't specify, so how do you know there is enough to light the bulb? I think this test question is correct for all intents and purposes, unless they include these other values.

[Crash Dummy Denno]

ok I'll see if i can explain this...

bulbs are purely resistave loads. the switch is assumed to be a short circuit when closed, but yes in reality there is a small amount of resistance.

the actual resistance of the bulb is temperature dependant. when current first passes through the cold filament, the resistance is much less than when the filament is hot. The time it takes to heat up can be disregarded for this because it's amost instant to the human eye.

take any bulb and you can figure the hot-resistance from the power consumed and the voltage across it. A 100 watt, 120 volt lamp has a resistance of 144 ohms when lit, from the basic equations below:

power=voltage*current
resistance= voltage/current

you've got a 144ohm resistor in parallel with a switch. the switch is assumed a short. you can throw in whatever practical switch resistance in there that you want & you wont see light. Yes a very small current will flow through the bulb and you can go back & calculate the power being consumed. Considering halogens are only about 7% efficient, whatever miniscule amount of power you have, roughly 93% of it is turned into heat rather than visible light.

you can go and make whatever assumptions you want to get the bulb to light, but the values arent given in the test probably to see whether or not people will make practical ones.

[978chris]

nerds make shit harder for themselves and never get shit accomplished.

engineers know the right assumptions to make, and are damn sexy too.

hmm i guess i'm half and half then.

i make shit harder for myself, but only in the interest of quality, and i DO get shit accomplished.

i dislike making assumptions, but I AM damn sexy.

[Crash Dummy Denno]

lol. i hide my geekiness by drinking dark beers and rocking the goatee

and dancing before each one of your day time talk shows

[978chris]

hahaha, owned.

[Kurlon]

nerds make shit harder for themselves and never get shit accomplished.

engineers know the right assumptions to make, and are damn sexy too.

http://www.x386.net/TTR/tech/cgi-bin/motorsim.cgi

Crap, guess I know which side I fall on.

[Kurlon]

and dancing before each one of your day time talk shows

Sorry to hear about the dog Buddha, can you kindly stop crying so the rest of the media can move on?

[SVRACER01]

96. only because i confused the battery answers. series = multiply voltage.

[mmracer37]

I must be stupid, only 92%. Maybe I should read the questions a little slower.

[FireFly]

gotta 70.
I should of went with my gut. I new the right answer to maybe 60% of the questions I Fudged, I just thought about it too much.

[OreoGaborio]

I just thought about it too much.

WHAT????? YOU???? nooooooo

Sup bro?