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baloon static in air
udit wrote:
i have another question suppose a hot air ballon is made still in mid air. then the earth will rotate under it so will the baloon reach from one one place to another standing at one place? answer required. No. A balloon is always (mostly) stationary with respect to the airmass that it is in. With respect to the ground it goes whereever the wind goes. The only time it's not stationary in the airmass is when something is dragging on the ground (as at launch or landing) or when it is passing through a windshear. |
#2
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baloon static in air
Keith Harwood wrote:
udit wrote: i have another question suppose a hot air ballon is made still in mid air. then the earth will rotate under it so will the baloon reach from one one place to another standing at one place? answer required. No. A balloon is always (mostly) stationary with respect to the airmass that it is in. With respect to the ground it goes whereever the wind goes. The only time it's not stationary in the airmass is when something is dragging on the ground (as at launch or landing) or when it is passing through a windshear. Or when wind direction changes. |
#3
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baloon static in air
Keith Harwood wrote:
udit wrote: i have another question suppose a hot air ballon is made still in mid air. then the earth will rotate under it so will the baloon reach from one one place to another standing at one place? answer required. No. A balloon is always (mostly) stationary with respect to the airmass that it is in. With respect to the ground it goes whereever the wind goes. The only time it's not stationary in the airmass is when something is dragging on the ground (as at launch or landing) or when it is passing through a windshear. So on moon, if we do same stunt and get up to 10m in space the land will move below -- -Gk |
#4
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baloon static in air
Ian Stirling wrote:
Keith Harwood wrote: The only time it's not stationary in the airmass is when something is dragging on the ground (as at launch or landing) or when it is passing through a windshear. Or when wind direction changes. Yup, but it's only momentary. The force arising from the wind change is applied over the whole crosssection of the ballon and is enormous compared to the mass of the balloon. From F=ma, the acceleration a must be very large. If the change in velocity of the wind is v then the time t to change the velocity of the balloon is given by v=at. v is small, a is enormous, t is terribly small. But the rate of change of the wind isn't all that crash hot, so if t is terribly small then v must be terribly small. If you do this properly using the rate of change of wind velocity to calculate F you'll find that to all intents and purposes the balloon is embedded in the air mass regardless of changes in the wind. |
#5
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baloon static in air
Dave wrote:
"George Kinley" wrote in message ... So on moon, if we do same stunt and get up to 10m in space the land will move below -- -Gk Aaah, but there's the rub...with no atmosphere, there's no medium in which a balloon can be buoyant, so you can't remain aloft. And with no air there's no wind, so the land won't move. It's the wind which makes the balloon move with respect to the ground. |
#6
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baloon static in air
Ian Stirling wrote:
Keith Harwood wrote: Dave wrote: "George Kinley" wrote in message ... So on moon, if we do same stunt and get up to 10m in space the land will move below Aaah, but there's the rub...with no atmosphere, there's no medium in which a balloon can be buoyant, so you can't remain aloft. And with no air there's no wind, so the land won't move. It's the wind which makes the balloon move with respect to the ground. Well, with no air, the coefficient of friction to the ground is significantly higher. Ah, very true. But getting back to the original premise, it seems from a few discussions around here that there are people who think that if you are attached to a moving body and suddenly become unattached, that you stop moving. This idea was debunked three and a half centuries ago. Why does it still persist? |
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udit wrote:
i have another question suppose a hot air ballon is made still in mid air. then the earth will rotate under it so will the baloon reach from one one place to another standing at one place? answer required. Before I read the other responses I have one question: How coupled to the rotating planet is the atmosphere the balloon is floating in? Seems the rotating planet isn't as much a concern as how fast the wind is blowing. TBerk |
#8
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But if the coefficient of friction to the ground is significantly
higher then... uhh... I dunno. |
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