- #1
Nantes
- 54
- 5
Sorry for the vague title, I really wish the title character limit was longer.
Suppose you are floating in space without gravity, but instead of a vacuum, there is air all around you. You turn on a powerful vacuum cleaner with the nozzle pointed directly ahead of you. Ignore torque/rotational effects. To which direction are you propelled, and why?
This is easy to imagine with something like a leaf-blower: the device thrusts air forward, the air will react with an equal and opposite force, and the person using the blower will be thrust backwards. But I'm having a really hard time justifying that because a vacuum cleaner does the reverse (suck air in), the person would develop forward momentum. It just doesn't seem right.
Assuming that's what happens, I'm having a hard time because I can't picture at what part of the process the air molecules would be able to react with an opposite force in a way that would propel the astronaut forwards. In fact, as I imagine it, as the air molecules hit the back of the vacuum cleaner after being sucked in, they would exert a force to the backwards direction, thus propelling the astronaut that way.
Is it that both ejecting and sucking in air propel you backwards?
Suppose you are floating in space without gravity, but instead of a vacuum, there is air all around you. You turn on a powerful vacuum cleaner with the nozzle pointed directly ahead of you. Ignore torque/rotational effects. To which direction are you propelled, and why?
This is easy to imagine with something like a leaf-blower: the device thrusts air forward, the air will react with an equal and opposite force, and the person using the blower will be thrust backwards. But I'm having a really hard time justifying that because a vacuum cleaner does the reverse (suck air in), the person would develop forward momentum. It just doesn't seem right.
Assuming that's what happens, I'm having a hard time because I can't picture at what part of the process the air molecules would be able to react with an opposite force in a way that would propel the astronaut forwards. In fact, as I imagine it, as the air molecules hit the back of the vacuum cleaner after being sucked in, they would exert a force to the backwards direction, thus propelling the astronaut that way.
Is it that both ejecting and sucking in air propel you backwards?