OK, the aerofoil principle I understand. Air flowing across the curved surface travels further than the air travelling across the flat surface means air pressure is less over the curved surface - and the airoplane rises. BUT!! what about when the airplane turns upside down???? How come the plane isn't "pulled/pushed" into the ground???
ive always wondered, right......... if you have a plane full of budgies, say 1 ton of budgies and the plane takes off- and all the budgies at the same time fly and hover in the air- does the plane become 1 ton lighter? mmmmmmmmmmm ive pondered it for sometime
Your bullets cannot harm me! My bingo wings are like a shield of steel!
The secondmemberoftheFantabulousTartanveggie fanclub
Originally posted by PeterCS: Ponder no longer, natty.
Budgies are light, it would take a world record to get a ton of them all in one plane, wing crammed up stiffly against wing like a giant tin of sardines with feathers.
I don't see that this ton of Joeys and Joannas would be able, let alone agree, to all getting airborne at the same time.
Otherwise, at normal parakeet avoirdupois, the weight would be small against that of the plane.
Also, all the budgies would poo more than their collective ton on the plane floor and (their favourite) deep in all the lady passengers' hair, having clawed their way in there to go to the toilet, so the plane might even end up heavier in the end.
I'd say the plane would crash, with all the flight attendants trying desperately to swat at the infestation of 1000 budgies clustered on their desperate sweating bodies and knocking eachother and the flight controls out, Air Control becoming inaudible above all the squawking, preening, pecking and crapping, the captain in despair of life having to abandon ship and eject him/herself through the nearest window, the autopilot going on the blink under the megatons of bird droppings piled up in the ladies' hairdos, etc.
If you were going along at 200mph in a train and fired a rocket that normally flies with a groundspeed of 200mph, in the opposite direction to you are travelling, would it appear to a person standing still beside the train, that the missile was stationary in the air in the position it was fired?
No, because the thrust of a rocket is actually conferred by the expanding gasses at the point in the engine furthest away from the exhaust nozzle. This is the rocket principle.
And what about that bullet? A completely different story.
Let's say that somebody on the train going 200 mph (approx 90 m/s) is firing from the back of the train and trying to hit his landlord standing by the track at a point that the train has already passed. All that matters to the landlord is the relative velocity of the bullet by the time it reaches him. Let's use a typical assault rifle round as an example, which leaves the gun at around 380 m/s. We would have to subtract the speed of the train to find the velocity of the bullet relative to the landlord when it reaches him. Subtracting the 90 m/s speed of the train still leaves 290 m/s as a relative velocity re: bullet/landlord, which is still enough to do a lot of damage.
However, to be true to the original question, if the bullet were traveling the same speed/velocity as the train it would never reach the landlord, and would appear to him to just drop down onto the track at the point at which it was fired, while the shooter would see it speeding away from him at 90 m/s, until it fell to Earth.
This is because by the time the bullet exits the gun barrel, the only energy it has is kinetic, and no energy is being added. Compare the rocket, which, assuming it has fuel, is being assisted by chemical energy converting to heat converting to kinetic energy to ADD speed/velocity to it.
This is the very problem, almost exactly, that inspired Einstein to create his Theory of Special Relativity. By the time he got around to General Relativity, it became a lot more complex, and likely beyond my understanding.
So the moral of the story is, if you have a very slow-firing gun, to shoot at your landlord as the train is approaching him. Then you get to ADD the speed/velocity of the train to that of the bullet relative to the shooter, and, alas, relative to the landlord.
- grrrrrrrr 
