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.
