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Can A Fly Stop A Train?! (more Technical)


boon racoon

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I watched this video once of a ground breaking experiment about a fly stopping a train, the fly stopped on the front panels of the trains window!

Then the train stopped at the next platform to pick up the passengers then moved onto its next destination! pretty ground breaking stuff.

But the fly didnt stop the train in your "ground breaking experiment".. the guy driving stopped the train.

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Yes in theory no in reality

but only on one condition

the fly must be traveling at half the speed of the train in the oppisite direction, Both the fly and the train have momentum. if the fly fully sticks to the train the train could possibly stop, if the momentum of the fly and the train were equal the fly would have to be 2 times the size of the train. so if the momentum of the fly was many times greater than the momentum of the train the fly could possibly stop the train. (copied from google)

so if the train had a mass of 5kg (toy Train) and the fly had a mass of 2.5kg but the fly was travleling at 5mps and the train at 2.5mps then the train would stop. Right? but there have beed no flies discovered that are half the size of a train so no

gav

Edited by Gavyn L
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Yes

but only on one condition

the fly must be traveling at half the speed of the train in the oppisite direction, Both the fly and the train have momentum. if the fly fully sticks to the train the train could possibly stop, if the momentum of the fly and the train were equal the fly would have to be 2 times the size of the train. so if the momentum of the fly was many times greater than the momentum of the train the fly could possibly stop the train. (copied from google)

so if the train had a mass of 5cm3 (toy Train) and the fly had a mass of 2.5cm3 but the fly was travleling at 5mps and the train at 2.5mps then the train would stop. Right?

gav

I can see no flaws in that whatsoever.

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Yes

but only on one condition

the fly must be traveling at half the speed of the train in the oppisite direction, Both the fly and the train have momentum. if the fly fully sticks to the train the train could possibly stop, if the momentum of the fly and the train were equal the fly would have to be 2 times the size of the train. so if the momentum of the fly was many times greater than the momentum of the train the fly could possibly stop the train. (copied from google)

so if the train had a mass of 5cm3 (toy Train) and the fly had a mass of 2.5cm3 but the fly was travleling at 5mps and the train at 2.5mps then the train would stop. Right?

gav

You've used volume (cm3) instead of mass (kg) but you'v pretty much got the essence of it.

As many other people have already said, then answer is no.

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Is this where the plane is on a long conveyor belt? the plane is still, but on a moving belt?

I think if the belt was going fast enough, the plane will take off? :blink::S

Yeah, I don't know what that guy's laughing at every time he hears that it would take off.

You can laugh at physics once you understand it :P

The conveyor would just make the wheels spin faster as the plane acellerated in a normal way!

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At Dans Point:

How can it?

For a plane to take off it has to force air downwards, if no air is coming towards it (thanks to the conveyor belt) then it can force anything down.

Much like a F1 car wouldnt create downforce in the same situation.

Edited by Has anyone seen my shoe?
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At Dans Point:

How can it?

For a plane to take off it has to force air downwards, if no air is coming towards it (thanks to the conveyor belt) then it can force anything down.

Much like a F1 car wouldnt create downforce in the same situation.

Err, read

'The conveyor would just make the wheels spin faster as the plane acellerated in a normal way!'

Therefore air is travelling past the wings.

The reason it still moves is because the planes engines move the air. The engines are unaffected by the conveyor belt, which just affects the wheels (which are like your front bike wheel and just spin!)

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They're a set of laws that explain the way the world work. You'll learn about it by the time you finish school, probably.

Ohhh you mean the laws that cant explain dark matter, gravity during eclipses, cold fusion, ESP, mind over matter, ghosts?

Physics is flawed because it was written by humans.

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Ohhh you mean the laws that cant explain dark matter,

That's a type of matter, discovered through use of the laws of physics. No problem there.

gravity during eclipses

We have laws for gravity, and they work perfectly (many verified during) eclipses :S

, cold fusion

Thats an invention, again trying to put into practice the laws of physics. i really dont know what you're trying to say here...

, ESP,

What's that?

mind over matter, ghosts?

Are you having a laugh? :lol:

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It wouldn't, ill explain better.

The plane is still ok? It's rolling along but it counter acted by the conveyor.

Now, to lift a plane you have to create lift commonly created by the wings and the aerofoil shape and not the engines. (notice the engines are pointed forwards not upwards)

As the plane moves through the air it is split by the wing, below the wing air is forced to move down, lifting the plane (rather then moving the floor down).

In this situation no air is flowing towards the plane as it is not moving through it, thus no air can be force down and no lift.

P.S. This isnt bullshit, ive got qualifications in airmanship etc :)

EDIT: ESP is extra sensory perception (how you can feel things like people looking at you etc)

Edited by Has anyone seen my shoe?
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It wouldn't, ill explain better.

The plane is still ok? It's rolling along but it counter acted by the conveyor.

Now, to lift a plane you have to create lift commonly created by the wings and the aerofoil shape and not the engines. (notice the engines are pointed forwards not upwards)

As the plane moves through the air it is split by the wing, below the wing air is forced to move down, lifting the plane (rather then moving the floor down).

In this situation no air is flowing towards the plane as it is not moving through it, thus no air can be force down and no lift.

P.S. This isnt bullshit, ive got qualifications in airmanship etc :)

EDIT: ESP is extra sensory perception (how you can feel things like people looking at you etc)

True, it is. The wing forces no air down, it creates a low-preassure area of air above the wing, so the wing is forced upwards. This is because the air travelling over the wing has to travel further than the air going under the wing, therefore spreading it out over a longer distance, lowering the pressure.

Besides that, ther IS air going over the wing!

The conveyor belt does shit all to stop the plane moving!

Would a treadmill placed under your front wheel while you are track-standing do anything to move you (if you didn't have you brake on)??

NO! :P

Plane wheels are free to move too, and as such the conveyor has no effect!

Edited by Extreme_biker0
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