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Why does the atmosphere stay round the earth?

The power of a vacuum is very obvious. Suction pads can defeat the earths gravity and lift a person up off the ground. So why does the vacuum of space not suck the air molecules away from earth, when the vacuum force is far greater than the earths gravitational pull? Am i overlooking something?

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Categories: Our universe.

Tags: Earth, gravity, Space, atmosphere, vaccum, Air.

 

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0urob0ross_ says:

 

There is no 'vacuum force'.  You're confusing pressure and vacuum.  The vacuum of space exerts no force on the atmospher.  Rather, the pressure of the atmosphere is a gradient.  The pressure is highest at the bottom of the atmosphere, where there is most mass above it.  The pressure reduces with height until it  there is no more atmosphere.  The pressure doesn't blast the atmosphere away because gravity holds the atmosphere to the Earth.  This gravity also gives the atmosphere weight, and the pressure is a result of this weight.  To be blown out into space, the atmospheric molecules would need to travel at escape velocity unti they escaped the pull of gravity from the Earth.  That's about 11 km/s.  The speed of sound is the fastest air can travel, about 0.33 km/s.  So the atmosphere isn't going to blow away into space.

Suction pads actually work because of the force of the atmosphere pressure compared to the low pressure inside the suction cup.  Gravity hasn't been defeated, it's just that the suction is strong enough to hold the weight of a man.

 

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Tags: Earth, gravity, Space, atmosphere, vaccum, Air.

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posted on 2009-09-22 21:11:17 | Report abuse

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Bjorn says:

Gravity!!

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Tags: Earth, gravity, Space, atmosphere, vaccum, Air, speed, molecules, staying.

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posted on 2011-12-10 20:57:19 | Report abuse


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hermawan says:

I think it's because atmosphere (gasses) are particles. According to Newton's law, there is a force between two particles F=G m*M/r*r where:

  •  
    • F is the magnitude of the gravitational force between the two point masses,
    • G is the gravitational constant
    • m is the mass of the first point mass,
    • M is the mass of the second point mass, and
    • r is the distance between the two point masses.

 So, the atmosphere stay the earth. If sometimes I think why air doesn't flow from the earth to the space because of the space air pressure is 0(nearly or exactly), I think the gasses do so, but if they reach the toppest high and when the force to outside plus centripetal force is equal or smaller than gravitational force, they will stay around the earth. Because of that, the air pressure at the toppest high is the smallest.

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Tags: physics, Earth, gravity, Space, atmosphere, vaccum, Air.

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posted on 2009-09-25 02:32:51 | Report abuse

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0urob0ross_ says:

No.  The gravitation force between two atmospheric particles is tiny.  Truely miniscule.  It is easily overcome by electrostatic charging of particles - so we would lose the atmosphere during sunlight hours and rain and snow and lightning and aurora etc.  Clearly, we still have an atmosphere, so we can ignore the tiny force between atmospheric particles.

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Tags: physics, Earth, gravity, Space, atmosphere, vaccum, Air.

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posted on 2009-09-25 04:20:33 | Report abuse


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hermawan says:

I think it's because atmosphere (gasses) are particles. According to Newton's law, there is a force between two particles F=G m*M/r*r. So, the atmosphere stay the earth. If sometimes I think why air doesn't flow from the earth to the space because of the space air pressure is 0(nearly or exactly), I think the gasses do so, but if they reach the toppest high and when the force to outside plus centripetal force is equal or smaller than gravity force, they will stay around the earth. Because of it, the air pressure at the toppest high is the smallest.

sssss
 (no votes)

Tags: Earth, gravity, Space, atmosphere, vaccum, Air.

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posted on 2009-09-25 02:32:55 | Report abuse


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hermawan says:

I think it's because atmosphere (gasses) are particles. According to Newton's law, there is a force between two particles F=G m*M/r*r. So, the atmosphere stay the earth. If sometimes I think why air doesn't flow from the earth to the space because of the space air pressure is 0(nearly or exactly), I think the gasses do so, but if they reach the toppest high and when the force to outside plus centripetal force is equal or smaller than gravity force, they will stay around the earth. Because of it, the air pressure at the toppest high is the smallest.

sssss
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Tags: Earth, gravity, Space, atmosphere, vaccum, Air.

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posted on 2009-09-25 02:32:57 | Report abuse


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eamonchee says:

Gravity dude. Gravity.

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Tags: Earth, gravity, Space, atmosphere, vaccum, Air.

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posted on 2009-09-28 07:14:09 | Report abuse


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