Tricky question

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A man flies a small light aircraft straight and level. Inside the cockpit is a fly flying. Does the fly’s weight contribute to the aircraft’s weight at all?
 

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yes .
 
dextercioby
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Of course not, unless the fly is attached to the walls of the plane (probably dead in the process)
 
daniel_i_l
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Of course not, unless the fly is attached to the walls of the plane (probably dead in the process)
actually, even if the fly is flying, it still contributes to the weight of the plane - because inorder to stay in the air it has to push down with it's wings which in the end exerts a downwards pressure to the floor. saying that the fly doesn't matter is like saying that a small boat floating in a bathtub doesn't increase the weight of the tub.
 
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My friend alex refutes this and asks: But what if the fly is flying directly above the air conditioning vent?
 
ZapperZ
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My friend alex refutes this and asks: But what if the fly is flying directly above the air conditioning vent?
Your "friend" alex should stop making you into his patsy and ask the question himself.

Zz.
 
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*making you into his patsy*:rofl: But I like frilly things :cry:
He cant be flucked to register so I'm just copy'n'pastin his replies from our e-mails at work... I think it would still add to the weight of the plane becasue it's still flying...

Now if the fly was dead and being suspended in midair by the updraft from the air conditioning vent would it add to the weight then?
 
ZapperZ
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*making you into his patsy*:rofl: But I like frilly things :cry:
He cant be flucked to register so I'm just copy'n'pastin his replies from our e-mails at work... I think it would still add to the weight of the plane becasue it's still flying...

Now if the fly was dead and being suspended in midair by the updraft from the air conditioning vent would it add to the weight then?
It is bad enough trying to explain things on here to someone directly. It will be worse, as far as communication is concerned, to try and carry a discussion via a 3rd party. I certainly have no patience to carry such a thing.

Zz.
 
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Fair enough but this question *If the fly was dead and being suspended in midair by the updraft from the air conditioning vent would it add to the weight then?* was mine :D Unless your stumped...:biggrin:
 
ZapperZ
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Fair enough but this question *If the fly was dead and being suspended in midair by the updraft from the air conditioning vent would it add to the weight then?* was mine :D Unless your stumped...:biggrin:
1. You will first note that your ORIGINAL question was already answered.

2. This is now a different question and when you add complexity to the problem, you also must make the question clearer by specifying if you make any assumption about the time of air flow - laminar or turbulent. You also need to specify if you assume that the air flow couples to the rest of the air in the room, i.e. is it a continuous flow, or simply a one-way flow?

You will notice that in physics, as soon as you try to go beyond the simplest scenario, then the QUESTION itself needs to be clearly presented if you expect any kind of unambiguous answer.

It is strange that you claim now that this question is "yours", when you said this earlier:

My friend alex refutes this and asks: But what if the fly is flying directly above the air conditioning vent?
Zz.
 
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Yeeeeea cos he said it was flying... and im saying if it were dead....:uhh:

OK, heres the evolved form of the question...

A man flies a small light aircraft straight and level. Inside the cockpit is a dead fly being suspend in midair by the updraft from the aircrafts AC. Does the fly’s weight contribute to the aircraft’s weight at all????
 
ZapperZ
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Yeeeeea cos he said it was flying... and im saying if it were dead....:uhh:

OK, heres the evolved form of the question...

A man flies a small light aircraft straight and level. Inside the cockpit is a dead fly being suspend in midair by the updraft from the aircrafts AC. Does the fly’s weight contribute to the aircraft’s weight at all????
It doesn't matter if it is suspended by the aircraft AC or by a string. If it is a closed system, then the answer is the same. If it is suspended by the draft coming from OUTSIDE the plane (windows open), then this is different. One can already see that if one removes the airplane - the bird will still be suspended. That is why I asked about how the air was "coupled" to the system, etc.

NOW do you see what I was getting at? If you only want to reveal only bits and pieces of the question rather than the whole question (something we REQUIRE if this is a homework or schoolwork-type question), then you will get the vague answer commensurate with your vague question.

Zz.
 
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:rofl: It's a stupid question that we made up at work to pass time! You really shouldn't be gettin so worked up over something so trivial, it's bad for your heart :uhh:
 
ZapperZ
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:rofl: It's a stupid question that we made up at work to pass time! You really shouldn't be gettin so worked up over something so trivial, it's bad for your heart :uhh:
We (or I) can't tell when a question is "serious" or "stupid". We treat all questions the same way. Besides, you were trying to ruffle my feathers by insinuating that I was 'stumped', which forced me to point out how ambiguous your question was for a clear answer.

If you wish to continue participating in this forum, keep that in mind.

Zz.
 
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Unless you're stumped... :rofl: It was a joke dude! Are you gonna stop me posting on the forum for having a sense of humor?

Anyway back to the question... In light of your answer some aspects need to be cleared up...

Where did you get the ridiculous notion of a bird being suspended when we were talking about a fly? Is it possible on a metaphysical level for a fly to spontaneously transform into a bird? If so could its weight be supported by the air conditioning system?
 
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ZapperZ
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Unless your stumped... :rofl: It was a joke dude! Are you gonna stop me posting on the forum for having a sense of humor?

Anyway back to the question... In light of your answer some aspects need to be cleared up...

Where did you get the ridiculous notion of a bird being suspended when we were talking about a fly? Is it possible on a metaphysical level for a fly to spontaneously transform into a bird? If so could it's weight could be supported by the air conditioning system?
Does it really matter if it is a fly, a bird, a bowling ball, etc, and if it is suspended via floating in air, by a string, or by an air balloon?

All we care about is (i) if the object is suspended in air (i) by what mechanism and (iii) if this mechanism is part of the system under consideration or not?

You'll notice that I spent considerable effort whereby I didn't just TELL you the answer, but I spent time trying to explain why it is so.

And note the POINT I was making when I brought up your statement about me being stumped. It wasn't about your posting, but rather in response to YOUR assertion that I shouldn't be "so worked up". I made no connection between your "joke" and your ability to post on here.

Zz.
 
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Oh ok...:yuck:...
As long as we are both on the same page that this is a TRIVIAL question, I'm not out to make air travel safer or create the next type of fuel...

Do you feel that you are doing a public service by answering an immensely banal question with the utmost authority and seriousness? It tests me to respect you as an "intellectual" if you cant see the funny side of this...you have a mother!:surprised
 
ZapperZ
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Oh ok...:yuck:...
As long as we are both on the same page that this is a TRIVIAL question, I'm not out to make air travel safer or create the next type of fuel...

Do you feel that you are doing a public service by answering an immensely banal question with the utmost authority and seriousness? It tests me to respect you as an "intellectual" if you cant see the funny side of this...you have a mother!:surprised
Some of the most profound insights into physics came out of trivial observations! I can give you tons of examples. You'd think that the "http://www.aip.org/isns/reports/2007/006.html" [Broken]" that you'd find in gift packages is utterly trivial. Yet, the physics could have an impact in manufacturing and nanotechnology! So no, any physics question in this forum is not taken to be trivial, unless it is obtuse, vague, and plain silly.

Furthermore, this IS a physics forum, and you asked a physics question in the physics section of the forum. If you had intended this to be nothing more than a joke, I would have suggested that you post this in the General Discussion forum, not in here, where the posts are more heavily moderated to stick closer to the topic.

Zz.
 
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DaveC426913
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Oh ok...:yuck:...
As long as we are both on the same page that this is a TRIVIAL question, I'm not out to make air travel safer or create the next type of fuel...

Do you feel that you are doing a public service by answering an immensely banal question with the utmost authority and seriousness? It tests me to respect you as an "intellectual" if you cant see the funny side of this...you have a mother!:surprised
Zapper, he's got you there. You are obviously out-of-touch with the spirit and intent of the Physics Forum - what with your mere 6000+ posts and four year+ attendance. mrcore64 clearly has his hand on the pulse of the PF forum, having been here for several days now. Clearly, he knows why PF members come here every day. :biggrin:



mrcore64: Seriously dude, you've virtually stepped off the elevator into the office on your first day of work, and by 9:02 you're telling people that you know how the place runs and insulting people.
 
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DaveC426913
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Where did you get the ridiculous notion of a bird being suspended when we were talking about a fly? Is it possible on a metaphysical level for a fly to spontaneously transform into a bird? If so could its weight be supported by the air conditioning system?
Your question is answered by the well-known logic puzzle that he refers to - birds flying inside a container truck.

If your puzszle can't be abstracted to this level and you can't see the principles involved, then you're not trying.

Now did you want an answer, or did you want to keep mocking him?
 
ZapperZ
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Zapper, he's got you there. You are obviously out-of-touch with the spirit and intent of the Physics Forum - what with your mere 6000+ posts and four year+ attendance. mrcore64 clearly has his hand on the pulse of the PF forum, having been here for several days now. Clearly, he knows why PF members come here every day. :biggrin:
You are so right!!

<sobbing hysterically>

Zz.
 
DaveC426913
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P.S. If the fly were dead and suspended above an AC unit, yes it wouold still add to the weight. The fly's weight pushes down on the air, which pushes on the AC unit, which pushes on the plane.

Consider scaling it up to an elephant over a very powerful AC unit in a 747. It becomes pretty intuitive that a plane with an elephant in it is heavier than a plane sans elephant. In fact, you don't even need the plane to fly. It weighs more on the ground. In fact, you don't even need the plane...
 
disregardthat
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If the fly suddenly dies in mid air, and then fall to the ground, then the weight would not contribute to the plane before it hit the ground.

The potential energy that contributes to the weight of the plane transform into kinetic energy on the way down, and then transforms into potential energy on impact. Isn't that right?

In an air conditioner, the air molecules constantly have to push the fly UP, pushing them DOWN, making the fly contributing to the weight of the plane. On a free fall, the fly's weight is not supported, so the weight should not be contributing to the total weight.
 
If the fly suddenly dies in mid air, and then fall to the ground, then the weight would not contribute to the plane before it hit the ground.

The potential energy that contributes to the weight of the plane transform into kinetic energy on the way down, and then transforms into potential energy on impact. Isn't that right?

In an air conditioner, the air molecules constantly have to push the fly UP, pushing them DOWN, making the fly contributing to the weight of the plane. On a free fall, the fly's weight is not supported, so the weight should not be contributing to the total weight.
As the fly falls to the ground, it is pushing air downwards, this air pushes on the plane's floor. There is no escaping the fact that the fly contributes to the plane's weight. Try as you may, but like a fly in a jar, there is no escape.
 

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