Looking for ideas for a Mechanical Engineering problem 21

[Lisa_247]

We are looking to take on an Aerospace Mechanical Engineering apprentice and I would like to give the candidates a problem to solve during the interview. I dont want anything too technical, just something that will give us an insight into how they approach problem solving, we are looking for someone who thinks logically but also thinks outside the box. Does anyone have anything I can use, or does anyone have any ideas please? Many thanks

 

[enginesrus]

Its a cube with a 45 degree cut surface and a small cube projecting off the center of that surface.

 

[JohnRBaker]

Actually there are TWO correct answers, and I would expect a candidate to see BOTH of them.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[3DDave]

There are likely many more than 2, like whole families. It could also be an curved surface.

 

[SuperSalad]

This was my first thought. Am I missing something?

Andrew H.

http://www.mototribology.com

 

[JohnRBaker]

All visible and hidden edges are properly represented in BOTH the Top and Front Views of the sample Drawing.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[SuperSalad]

In that case:

Spoiler

A diagonal 2-dimensional line

Andrew H.

http://www.mototribology.com

 

[JohnRBaker]

Here are the two solutions which have been traditionally offered when confronted with this 'test':

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[FACS]

Just ask them to explain engineering Stress and strain. Great question to see if they remember something so simple.

BTW: Mintjulip was not correct in his reasoning to put the pump down below. The correct answer was the 32-foot vacuum limit of a pump.

 

[FACS]

Well, If John R. Baker is using 3rd angle projection, I would say that the views are wrong.

The front view is below the top view. The right side view is to the right of the front view.

 

[GregLocock]

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[CWB1]

If they have worked in a technical position prior I would ask them to describe their work. If not, I would ask that they describe their technical background, hobbies, or why they are going into engineering. Engineering is easy, communication is difficult and these questions should provide plenty of opportunity to chase the conversation down technical rabbit holes to give you an idea of their abilities and thought-process. Personally, I would NOT ask them to solve a textbook style question like those shared above as most technically-competent folks will find them insulting and often show poor preparation or knowledge on the part of the person asking.

Over half of the graduate engineers I've asked get the answer wrong.

I'd argue that there is no incorrect answer based on the limited info given as I'm sure there are many ways to make a pump work in any given location.

 

[handleman]

I'm sure there are many ways to make a pump work in any given location.

I'd be curious to hear a method for making the pump work from the roof.

 

[3DDave]

Easy - put a hose from an air pump to a fitting on the drum and a second hose to a second fitting that has a dip tube. It costs a little more but the guy on the roof has control over the pump and can watch the destination. It also means the pump can be used on corrosive materials without using a corrosion resistant pump.

 

[3DDave]

Spoiler

 

[GregLocock]

Yup

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[Artisi]

MintJulep: just for clarification and correctness, irrespective of NPSHr at ground level doesn't necessarily mean a pump will be self-priming - this is entirely dependent on pump design.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[chicopee]

The question posed by Compositpro has a lot to do with the Net Positive Suction Head requirement. If the pump is too far up the line than there is a chance that water will turn into a vapor state ( i.e.,bubble up), so to be fair with the applicants perhaps flow rate, water temperature, friction loss thru piping should be stated. Static head of water in drum to pump inlet should also be highly considered due to the choice of the pump placement.

 

[btrueblood]

Low cost method: No pump. Build a fire (using trash from the dumpster) under the bottom barrel and pipe the steam to the upper barrel. Some of the water will condense in the upper barrel. Refill lower barrel as required until you achieve desired water level in upper barrel.

...just "thinking outside the box", and have been having discussions about distilling with some colleagues recently. Our local winery/brewery scene has had a plethora of startup distilleries come and go, and we think the problem is these guys don't understand what barrel aging does for fine liquors.

 

[IRstuff]

Steam could take a while; a slight modification would be to have the pipe at the BOTTOM of the boiler and use the trapped steam as the pressure for pumping the liquid water upwards. That's how your cheapo coffemakers operates, but I'm not clear whether you could generate sufficient steam pressure to push the water column up 5 stories; now, that's a lot of coffee!

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[CWB1]

I'd be curious to hear a method for making the pump work from the roof.

Me too. Therein lies the problem, with limited info we cant positively deem a task impossible or an answer incorrect. The pump could be assisted with positive pressure in the lower tank or negative in the upper. We don't know anything about the pump nor the volume of water in the system much less each tank, whether the tanks are closed vessels or open to atmosphere, whether/not there is flow into the lower tank or out of the upper, nor do we know if we need to pump continuously or if we can use an intermittent cycle. Even gravity could totally hinder or be a great help. Not to be terribly facetious but many careers have been made by accomplishing tasks deemed impossible by others who didnt consider every detail, hence my hesitancy to pose general questions bc the best answer is usually "it depends."

To get back to something more useful for the OP, another personal favorite "test" for all engineering candidates of mine is simply to give them a tour of the shop to see what questions they ask and what relevant knowledge or experience they might have. In most cases its usually pretty easy to tell those looking for a paycheck from those looking for a career.