If the earth really rotates
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wad will happen if u float in the sky..say 100 feet above..does it mean that the land below u will move? so if this really happen y do we need to take plane and go to other country? juz float in the sky can liao rite?
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can u float in the air for so long?
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assumeOriginally posted by ctstalin:can u float in the air for so long? -
u're held in place and still moving together with earth as a system due to gravity acting on that system.Originally posted by Classyfied:wad will happen if u float in the sky..say 100 feet above..does it mean that the land below u will move? so if this really happen y do we need to take plane and go to other country? juz float in the sky can liao rite? -
I concur.Originally posted by ^tamago^:u're held in place and still moving together with earth as a system due to gravity acting on that system. -
subject to earth's centripetal gravitational fieldOriginally posted by ^tamago^:u're held in place and still moving together with earth as a system due to gravity acting on that system. -
using conservation of momentum law, when u're on the ground u're already travelling on the same speed as the rotation of earth. assuming no external forces act on u other than u being lifted up to above the ground, u're still travelling at the same speed as the earth is rotating.
the same reason why when u jump up and down, u land on the same spot. gravity and rotation of earth are forces on different dimensions/axis. -
please also take note of the coriolis effect
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yup. gravity is a result of centripetal acceleration.Originally posted by poon cho tang:subject to earth's centripetal gravitational field
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nice.Originally posted by poon cho tang:please also take note of the coriolis effect
http://en.wikipedia.org/wiki/Coriolis_effect -
there's an article on wat will happen if earth stops rotating suddenly, then we'll be flung away from our positions since we'll still be travelling at the speed the earth was rotating (but not fall out of earth as the speed calculated is still less than the escape velocity of earth), and how buildings will collapse under the great force, and a great atmosphere wind will be created, and a fireball will consume us all.
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yeOriginally posted by ^tamago^:using conservation of momentum law, when u're on the ground u're already travelling on the same speed as the rotation of earth. assuming no external forces act on u other than u being lifted up to above the ground, u're still travelling at the same speed as the earth is rotating.
the same reason why when u jump up and down, u land on the same spot. gravity and rotation of earth are forces on different dimensions/axis.
always relative to the earth's gravity -
assuming what you say is true, what happens if i wanna go north or southOriginally posted by Classyfied:wad will happen if u float in the sky..say 100 feet above..does it mean that the land below u will move? so if this really happen y do we need to take plane and go to other country? juz float in the sky can liao rite? -
Have u ever notice, when travelling in a car at night, and u see that the moon in the sky seem to be following you??
Ok, lets put it this way: try driving, and chase a sunset. You will lose ... because earth's rotation is extremely fast and it takes an aircraft flying at around 500Km/h to catch a setting sun.
So even if you float or hover a helicopter, you still need to be moving roughly at the speed of an aircraft.
Also, do not discount the fact that Earth is also orbiting the sun. This adds more speed.