Force on a body through air pressure

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Discussion Overview

The discussion revolves around the feasibility of lifting a heavy object, specifically a block of steel with a weight of 1000N, using air pressure within a sealed container with a movable piston. Participants explore the principles of air pressure, its directional effects, and potential applications in lifting mechanisms.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that by pressurizing air in a sealed container with a movable piston, it may be possible to generate a force sufficient to lift a heavy object, as described by the formula pressure = force/area.
  • Others argue that air pressure acts in all directions and that without creating a vacuum on one side, the net effect would cancel out, making it ineffective for lifting.
  • A participant suggests that gas pressure does not transmit through solid surfaces, indicating that only the movable surface would experience a real effect from the pressure.
  • Some participants mention that this concept is similar to how airplanes generate lift, with differences in pressure above and below the wings due to airflow.
  • Another participant introduces the idea of pneumatic lifts as a more applicable example of using air pressure for lifting heavy objects.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of using air pressure to lift heavy objects, with some supporting the idea while others challenge its feasibility based on the principles of air pressure and its directional effects. No consensus is reached.

Contextual Notes

Participants reference various configurations of pressure systems, such as pistons and pneumatic lifts, but do not resolve the underlying assumptions about air pressure dynamics and their applications in lifting mechanisms.

Nythe
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If a body,let's say a big block of steel, has a net downward force of weight of 1000N, would it be possible to lift the block using air pressure? I mean, if you put air in a completely sealed container with a movable piston on top and you pressurized such air to an appropriate pressure, then by formula: pressure=force/area, wouldn't it be possible to achieve a force equal to or more than the weight of the body? And if this could be done and the entire container is attached to the underside of the body, would the body not constantly levitate a little because of the net upward force?
 
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Welcome to PF.

Air pressure acts on the top and the bottom of the deviece, so it cancells out. The only way to get air pressure to move something is to use a vacuum pump to remove air from one side.
 
Yes, its true that air pressure acts in all directions but if, in this container, let's say a cuboid for hypothetical purposes, 5 of the 6 sides are completely sealed and one side is a movable surface, the force would act on all sides but would only have a real effect on the movable surface. I don't think gas pressure will transmit through a solid, immovable surface.
 
Nythe said:
If a body,let's say a big block of steel, has a net downward force of weight of 1000N, would it be possible to lift the block using air pressure? I mean, if you put air in a completely sealed container with a movable piston on top and you pressurized such air to an appropriate pressure, then by formula: pressure=force/area, wouldn't it be possible to achieve a force equal to or more than the weight of the body? And if this could be done and the entire container is attached to the underside of the body, would the body not constantly levitate a little because of the net upward force?
Could you pressurize air within some container to lift a piston plus the added weight resting on it? Sure, why not.
 
Nythe said:
Yes, its true that air pressure acts in all directions but if, in this container, let's say a cuboid for hypothetical purposes, 5 of the 6 sides are completely sealed and one side is a movable surface, the force would act on all sides but would only have a real effect on the movable surface.
This arrangement is generally called a "piston". Although typically they are made cylindrical rather than cubic.

Nevermind, I see Doc Al already mentioned that.
 
Nythe said:
If a body,let's say a big block of steel, has a net downward force of weight of 1000N, would it be possible to lift the block using air pressure?

Yeah, isn't that how airplanes work?
 
Lsos said:
Yeah, isn't that how airplanes work?

Good example, the velocity at the top of the wings is faster so the pressure is more under the wings. And an airplane is heavy.

Air pressure is so strong on Earth that if you depressurized your house your lungs would burst and your blood would boil. and then your house would implode.
 
A better example would be a pneumatic lift.
 

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