geogob
Koohii o nomimasu ka?
No difference. Friction with water is higher, but floats are designed to come out of the water like a speed boat does as speed relative to the water builds up. But regardeless of the friction which is higher, the water is still free flowing under and around the floats and the plane does not depend on the water flow to accelerate relatively to the air. If you have a strong current in the opposite direction of the plan, you'll need more power to go against the force of the water, but once you start moving against the water and relative speed builds up, the floats move out of the water and the effect of the frictions becomes less important. At take off speed, whether the water has a strong current or is not moving at all is close to negligable.
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You really have to get the car image out of your mind. On a car if the base on which the wheels are moves in the opposite direction, the car won't move relatively to a fixed reference point. This is because it's the wheels that push the car forward. With an airplane it's the propeller or the jet engines that push air behind the airplane, creating thrust. This thrust pushes the airplane forward.
Technically, you could put wings on a car and accelerate the car (with the wheels) fast enough to take off. But once in the air, there won't be any more accelaration (wheels obviously not touching the ground) and the flying car would slow down and land (or crash, how ever you call it). Actually this wouldn't go well as the with the increasing lift as speed builds up, the pressure on the wheels would be reduced as well as frinction between the wheels and the ground, making them less efficient. With that theoretical flying car, if your car starts to accelerate on a moving runway, as described in the original question, the flying car would never move relative to a fixed reference point and never get any airspeed. No takeoff (and, thank god, no crash).
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You really have to get the car image out of your mind. On a car if the base on which the wheels are moves in the opposite direction, the car won't move relatively to a fixed reference point. This is because it's the wheels that push the car forward. With an airplane it's the propeller or the jet engines that push air behind the airplane, creating thrust. This thrust pushes the airplane forward.
Technically, you could put wings on a car and accelerate the car (with the wheels) fast enough to take off. But once in the air, there won't be any more accelaration (wheels obviously not touching the ground) and the flying car would slow down and land (or crash, how ever you call it). Actually this wouldn't go well as the with the increasing lift as speed builds up, the pressure on the wheels would be reduced as well as frinction between the wheels and the ground, making them less efficient. With that theoretical flying car, if your car starts to accelerate on a moving runway, as described in the original question, the flying car would never move relative to a fixed reference point and never get any airspeed. No takeoff (and, thank god, no crash).
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