You are trapped on a frictionless sheet of ice. If you trued to escape by blowing, you would have to inhale eventually, which would counteract the force you gained by blowing. However, if you were to turn your head and inhale facing the east, you would gain some force moving east. If you then turned your head and exhaled towards the west, you would gain more force towards the east. You could use this to build your speed eastward.

Is this correct, or am I missing something?


2 Answers 2


When you inhale you create an area of low pressure immediately in front of your mouth, like the Venturi of a carburetor. You would be drawn toward the low pressure area as the incoming stream of air accelerates down your throat, maintaining the low pressure in front of your mouth. Until your lungs are full.

When you turn 180 degrees and exhale, you reverse the Venturi effect, creating an area of low pressure inside your mouth, and expel a jet of heated, pressurized, more energetic air. The air jet propels you across the ice, just as the incoming area of low pressure drew you across the ice.

Heat is exchanged from your body to the environment, and work is done. Jet airplanes use such work to fly. Yes, you could use this work to escape the ice, but it would be a slow process and you might burn up all your energy before getting anywhere because human lungs just aren't powerful enough to move the human body like a jet engine.

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    $\begingroup$ Not necessarily so slow a process... every breath just keeps adding more speed (no loss from friction), so you could get going quite fast eventually. And once you build up some speed you can just breathe normally, since the surface is frictionless you'll just keep going (with a small speed modulation in phase with your breathing). $\endgroup$
    – Kyle Oman
    Apr 30, 2015 at 21:30
  • $\begingroup$ Kyle Oman: I think you're right. It's wonderful what can be accomplished on a frictionless surface! $\endgroup$
    – Ernie
    Apr 30, 2015 at 21:33
  • $\begingroup$ One could also use a snorkel, in the appropiate direction, so one need not have to turn the head. $\endgroup$
    – anna v
    May 1, 2015 at 5:08
  • $\begingroup$ It should be noted that turning your head will also turn yourself / the sheet you're on a tiny bit, which you might need to account for to stay on course; your turn is not exactly 180 degrees. $\endgroup$
    – Arc
    May 1, 2015 at 23:16

One more option is there. First lay down on your back. Then do the knee stretch and bend in a horizontal position. How powerfully you throw your let, that much powerfully you will move head on. Another option spit strongly with all the possible fluid and power you've. You'll move in the opposite direction but facing backwards. Beware not to hit anywhere!!!!


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