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Current question is related to some of answers given to this question.

The answer given by hapa that has been confirmed by some other users in their answers, is as below:

If there is no friction, you can still move by conservation of momentum. Take some stuff with you that you don't need. Throw it away in the opposite of the direction you want to go!

My question is:

Can we throw some stuff in a perfectly friction-less (thought) world at all (if there is no support around us)?

I think we can't. Because for throwing, we primarily need to move some part of our body (for example our arm). And I think we cannot (or maybe we shouldn't) move some part of our body in a perfectly friction-less world. Because according to the first law of Newton ("A body maintains its state of motion unless unbalanced external force acts up on it"), for make our arm to move, we must exert force on it. According the third law of Newton ("When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.") the arm will exert a force on rest of our body. As there is no friction (there is no support), arm will move in a direction and rest of the body will move in the opposite direction. Thus, I think if we move some part of our body, we will be exploded finally.

I think for exerting any contact force, we need a supporting force exerted on us.

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lucas
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    You are wrong. Put two fingers trough the hole in the donut and close them... voila... perfectly captured donut. Even in a perfectly frictionless world non-trivial topological shapes can hold together. Friction, by the way, only implies forces parallel to a surface, it says nothing about forces perpendicular to it, and these forces may very well be attractive. – CuriousOne Jul 15 '16 at 06:27
  • @CuriousOne Thank you because of your attention! But I mean any kind of supporting force. And in the question, I assumed that there is no support. For example, in the space (out of the Earth atmosphere). – lucas Jul 15 '16 at 06:31
  • @CuriousOne In addition, we want to throw some stuff parallel to the surface if there was a surface. – lucas Jul 15 '16 at 06:33
  • Astronauts do it all the time while in the orbit. It would require some practice to do it right, but there is nothing that makes it impossible. – kpv Jul 15 '16 at 06:55
  • @kpv Thank you! But I think they have some kind of supports, for example cables that connect them to the spacecraft. – lucas Jul 15 '16 at 06:59
  • @lucas: Not necessarily, they can be floating inside the station and can through stuff around, which would not only make them move, but would also make them rotate some. For example, two floating astronauts inside the station can push each other, which is like they are throwing one another. – kpv Jul 15 '16 at 07:02
  • @kpv I am not sure. But I think there is air pressure inside the station that violates the question thought conditions. – lucas Jul 15 '16 at 07:06
  • @lucas: Even on earth, we are throwing earth in a way, but due to its mass, we never realize doing that. The support you are talking about is nothing but something we throw, but does not seem to be moving. Basically, friction is providing us a means to throw something, nothing else in this context. – kpv Jul 15 '16 at 07:09
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    @lucas: One more way to look at it is - suppose you are on a friction less surface on earth. You probably will not be able to move horrizontal, but nothing stops you from jumping vertically up. When you jumping up, you are trying to throw earth with your feet. Due to earth's mass, you get thrown. Same way, if you throw anything heavy in any direction, you move in opposite direction. – kpv Jul 15 '16 at 07:20

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