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    I've been taught that free fall is when something falls under the sole influence of gravity.

    But obviously you would get air resistance when falling (eg. out of a plane), so would that be classed as free fall or not? If not, then how can something ever be free falling (since there will always be drag forces)?

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    Depends if the planet you're falling on has an atmosphere.
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    (Original post by vector12)
    I've been taught that free fall is when something falls under the sole influence of gravity.

    But obviously you would get air resistance when falling (eg. out of a plane), so would that be classed as free fall or not? If not, then how can something ever be free falling (since there will always be drag forces)?

    Thanks
    If you define "free-fall" as an object falling under the sole influence of gravity then no, somebody falling out of a plane would not be in free-fall because as you say, they're under the influence of drag forces. The wikipedia article for free fall does state that "free fall" is usually used more loosely than the above definition though.
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    (Original post by Plagioclase)
    If you define "free-fall" as an object falling under the sole influence of gravity then no, somebody falling out of a plane would not be in free-fall because as you say, they're under the influence of drag forces. The wikipedia article for free fall does state that "free fall" is usually used more loosely than the above definition though.
    Ah okay, so if you use that strict definition then barely anything (if at all?) would ever be in free fall because it would always be facing some kind of drag force like air resistance? Nothing could ever fall without some kind of drag force, could it?
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    (Original post by vector12)
    Ah okay, so if you use that strict definition then barely anything (if at all?) would ever be in free fall because it would always be facing some kind of drag force like air resistance? Nothing could ever fall without some kind of drag force, could it?
    If you're going to be extremely pedantic then yes, true free-fall is impossible because there's probably always going to be some force apart from gravity acting on an object such as drag, or electric/magnetic fields, etc. In practice though it's perfectly possible to get situations where these other forces are negligible and for all practical intents and purposes it is free-fall, e.g. on a planet with no atmosphere or in a vacuum or in space.
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    (Original post by Plagioclase)
    If you're going to be extremely pedantic then yes, true free-fall is impossible because there's probably always going to be some force apart from gravity acting on an object such as drag, or electric/magnetic fields, etc. In practice though it's perfectly possible to get situations where these other forces are negligible and for all practical intents and purposes it is free-fall, e.g. on a planet with no atmosphere or in a vacuum or in space.
    Thank you! Bit of a silly question, but why would there be less air resistance/drag in space than on earth?
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    (Original post by vector12)
    Thank you! Bit of a silly question, but why would there be less air resistance/drag in space than on earth?
    Edit: Is there air in space?
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    (Original post by vector12)
    Thank you! Bit of a silly question, but why would there be less air resistance/drag in space than on earth?
    How much air is there is space?

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    (Original post by Plagioclase)
    xxx!
    Study help! No complete solutions...

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