If..

[Sensei Kiisu]

I've just come off an 8 hour flight from Florida heh, but was thinking about the speed the air-craft was going...

let's say you have an object that you suspend in mid air inside the aeroplane without it being connected to it directly, while it is in motion, will the object be hit by the plane from inside or will it travel at the same speed as it..? I couldn't think of a reasonable object that'd make any sense for this scenario, but!

If you had a fly in a jar (who knows why.. XD) - and released it, which of the above would happen? A fly, flying at 672mph would be pretty impressive (':

[Zhangir]

I think (I am not a scientist though) if you had a fly in an airplane it wouldn't hit stuff, but go on flying, because there is no wind, etc. inside the airplane.
Basically if an object flies around inside an airplane it is pretty much the same as if it would fly on earth (of course if the airplane is fully covered, not one of those World War I types)
I mean it wouldn't be flying because of its wings (the fly), but because of the airplane's engines, same as people inside it.

[Sensei Kiisu]

I think (I am not a scientist though) if you had a fly in an airplane it wouldn't hit stuff, but go on flying, because there is no wind, etc. inside the airplane.
Basically if an object flies around inside an airplane it is pretty much the same as if it would fly on earth (of course if the airplane is fully covered, not one of those World War I types)
I mean it wouldn't be flying because of its wings (the fly), but because of the airplane's engines, same as people inside it.

I thought maybe that - however if it is not touching anything in the aircraft, then there is no force upon it which 'forces' it to travel at the same speed as the craft, unlike when we travel, the force of us being pushed back against our seat is enough to keep us with it... if that makes sense? (':

[Juvenal]

I thought maybe that - however if it is not touching anything in the aircraft, then there is no force upon it which 'forces' it to travel at the same speed as the craft, unlike when we travel, the force of us being pushed back against our seat is enough to keep us with it... if that makes sense? (':

There is no force required to keep something moving at its current speed. Newton's 1st Law of Motion confirms this.

Assuming the aircraft is flying in a straight line and at constant speed, then an object dropped within the plane will simply fall to the floor in the normal way, as if both object and aircraft were stationary.

If the plane is under acceleration, then the object would appear to accelerate in the opposite direction as well as falling. But an observer in the plane can easily tell that it is the aircraft and not the object accelerating, because they will feel the plane's acceleration themselves.

Haven't you noticed that you only feel a force pushing you back into your seat during take-off and the climb to cruising altitude? Once the seat-belt lights go out, there is no longer any acceleration that you can feel (although the aircraft has to continue to thrust in order to overcome air-resistence). I suppose you might be confused by the fact the the aircraft is tipped up at the front during level flight (i.e. the flight is level, but the aircraft iself isn't).

[Elfdude]

If on the other hand your vehicle is moving at 60 MPH and you throw an object forward at 30mph the object will be traveling (relative to the ground) 90 mph. However if you drop the same object inside the momentum of it moving forward is preserved and since the air isn't pushing backwards on it (as it would be outside the vehicle) the momentum would be preserved perfectly. If (for sake of argument) we pretend there was no gravity and it was just a car moving at 60 MPH if you let the object go inside of the car the object would continue to move 60 mph relative to the surface that the vehicle is driving on but it would appear to float from the perspective of the person in the car. From outside both objects would appear to move at the same speed.

[vlach]

First of all to be in that situation the plane would accelerate the object to its speed so the object is already travelling at the planes speed just as you are there would have to be additional forces, as previously said the plane accelerating or otherwise for the object to have non-zero velocity with respect to the planes frame of reference

[MrMofo]

When you got up to go to the bathroom were you smushed flat against the rear of the plane?

[Vizsla]

Frame of reference:
The earth rotates at roughly 1000 mph at the equator (although not at the Poles). The earth rotates round the sun at 66,000 mph. The solar system is moving towards the star Vega in the constellation of Lyra at 43,000 mph. The solar system is rotating around the centre of the galaxy at 483,000 mph. The galaxy itself is moving at 1.3 million mph (relative to the CBR).
http://www.astrosociety.org/educatio...1/howfast.html
So depending how you look it at every fly on earth is always moving at 1.3 million mph.

[Rolanbek]

The above posters are correct, the object falls to the floor of the plane in a straight line (to an observer in the plane), describes a parabola to an observer of on the ground (with the ability to look a small objects at great distances with metal sheets in between) and an infinitesimal arc section of a spiral for a solar-static extraterristrial. etc etc.

A fly released in plane just buzzes about as normal, the added spped is no more apparent than it is on you the observer.

The plain (or plane?) fact is a fly released from a plane travelliing at 672mph would be transferred into a subzero wind-chill and from its frame of reference would hit wind resistance very hard. Terminal velocity is very low for a fly based on it's low mass a comparatively high surface area say no more than 50mph, so based on that the fly would begin breaking hard immediately.

Physiologically he fly would disintegrate as it was ripped apart by 600mph winds. and the fragments would freeze in the low air temperature and high wind chill enviroment

If you double the speed the friction would incinerate the fragments before the chill could freeze them.

R

[Tacitursa]

Isnt it to do with pressure of the cabin more than anything else?

[Rolanbek]

Isnt it to do with pressure of the cabin more than anything else?

isn't what?

If you mean what will happen, suppose we have all rather assumed that the cabin is pressurized so that you could observe.

If the cabin is at local pressure for a jet aircraft in middle of is flight (crusing I suppose?) then the fly would probably struggle to create downforce to fly and drop to the deck, before suffocating in the low pressure atmosphere.

probably better if we could all breathe in the plane without masks, including the fly.

R

[Tacitursa]

isn't what?

If you mean what will happen, suppose we have all rather assumed that the cabin is pressurized so that you could observe.

If the cabin is at local pressure for a jet aircraft in middle of is flight (crusing I suppose?) then the fly would probably struggle to create downforce to fly and drop to the deck, before suffocating in the low pressure atmosphere.

probably better if we could all breathe in the plane without masks, including the fly.

No i mean if the windows/door is missing and you drop something it wont just fall to the ground it will fly out of the windows/door at high speed.

[cpdwane]

No i mean if the windows/door is missing and you drop something it wont just fall to the ground it will fly out of the windows/door at high speed.

Well, if it's a plane the doors and windows shouldn't be open during the flight because then the pressurisation would be comprimised.

But if, say, you are in a car and the window is open then that won't chnge anything, the objec will still appear to simply be fallling (unless it happens to fal out of the window, in which case it would appear to fly backwards due to air resistance.)

[removeduser_4536284751384]

I actually managed to test this out in real life, believe it or not. I got the wrapper from a small packet of crackers, road at the back of a 25 year old bus and threw the packet into the air. It floated because of the way air was rushing in to the bus. It only fell after about 20 seconds.

[Sensei Kiisu]

Hmmm... I can kind of understand what you're all saying, I just can't seem to get my head around this conundrum, ...

Let's try a different scenario here, it may help me understand more..

Scenario 2:

for the sake of the argument, we have a Remote Controlled Helicopter... NOW - we go on a TRAIN, which eliminates 'the cabin is pressurised' argument etc... so, you're sat there, going around 70 MPH, and then you make the helicopter hover. Now, does the RCH go smoosh into the back of the train? Since there is no force making it go forward... :/

[Vizsla]

The helicopter is already going forward at 70mph before it takes off.

[Sensei Kiisu]

The helicopter is already going forward at 70mph before it takes off.

Yes, but if it is hovering, with no forward force being applied after a while surely it'd decelerate and then...

SMOOSH? O.o

[Vizsla]

Before take-off it is sitting in the train going forwards at 70 mph. After take-off it is hovering in the train and going forward at 70 mph.
It doesn’t appear to be going forward at 70 mph because you are also in the train and going at 70 mph.
If the train driver suddenly applied the brakes very hard then you and the helicopter would attempt to continue moving forwards at 70 mph. This why we have seatbelts in cars.


You're just taking the piss, aren't you.

[Sensei Kiisu]

Before take-off it is sitting in the train going forwards at 70 mph. After take-off it is hovering in the train and going forward at 70 mph.
It doesn’t appear to be going forward at 70 mph because you are also in the train and going at 70 mph.
If the train driver suddenly applied the brakes very hard then you and the helicopter would attempt to continue moving forwards at 70 mph. This why we have seatbelts in cars.


You're just taking the piss, aren't you.

I am, really, REALLY not... I just can't get my head around how something which has no FORCE applied to it, when it is not moving, can continue to travel at the same speed...

IF you jump from a moving car, and SOMEHOW remain airbourne, (let's say we turned off gravity a second here), you would NOT continue to travel at say 60mph, because there is no car to keep you traveling at that speed, and thus you would decelerate and come to a stop, still hovering in the air at 0mph.

Now if we apply this same principle to the train scenario, but we have replaced the floating human - with a floating RC helicopter, which still has no moving force... then...?

[Vizsla]

Don’t try this at home kids.
When I was a school kid a few London buses still had an open platform at the back. The following story is one reason they got rid of Routemaster busses.
Sometimes we’d jump off the back while the bus was still moving and the bus conductor was looking the other way. Usually we’d wait until the bus was almost stationary because of traffic or whatever. After a while it became a game to see who could make a successful jump while the bus was moving. The faster the bus was going the more Kudos and the greater the risk of serious injury.
So believe me when I say that when you’re travelling at a speed of 30 mph and you jump into the air you do not slow down. You continue to move at 30 mph until something decelerates you. Often something hard and pavement or lamppost shaped.
Conservation of linear momentum – that’s just how the world works. If you don’t like it you’ll have to find a different universe to live in.
http://en.wikipedia.org/wiki/Momentum