Moving in space

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OK to my knowledge everything moves by using friction,or pushing off of something but how would say a spaceship move, i know that im over looking somthing very obvious but im just not sure what it is.
 

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  • #2
quasar987
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In space, a spaceship moves according to newton's first law (if it is at constant speed, it will continue to do so eternally, since no force is acting on it [don't nitpick!]), and it changes its direction or accelerate by making use of the law of conservation of linear momentum: it will propulse stuff in the direction opposite from where he wants to go.
 
  • #3
Pengwuino
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For example, the reason a space ship would fly is basically its firing mass out of its exaust and according to Newton's "Equal and opposite reaction" (forget the #.... god im horrible), an equal amount of momentum will be applied in the opposite direction thus propelling the rocket through space. Fricton has nothing to do with movement other then the fact that if there is friction, its speed will be reduced.
 
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ok i already understood what you guys are saying but i cant wrap my mind around the fact that it has nuttin to push off of or anyhitng like that, that is what i ment when i was mentioning friction.
 
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ZapperZ
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Tido611 said:
ok i already understood what you guys are saying but i cant wrap my mind around the fact that it has nuttin to push off of or anyhitng like that, that is what i ment when i was mentioning friction.
Hold a ball while standing on skates on ice. Now throw the ball in one direction. You will see that you will move in the opposite direction. This is conservation of linear momentum. The volume of gasses escaping from jet engines and rocket nozzles do just that.

Zz.
 
  • #6
Pengwuino
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ZapperZ said:
Hold a ball while standing on skates on ice. Now throw the ball in one direction. You will see that you will move in the opposite direction. This is conservation of linear momentum. The volume of gasses escaping from jet engines and rocket nozzles do just that.

Zz.
Or shoot a gun. much funner and safer!
 
  • #7
Pengwuino
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Tido611 said:
ok i already understood what you guys are saying but i cant wrap my mind around the fact that it has nuttin to push off of or anyhitng like that, that is what i ment when i was mentioning friction.
Friction isnt "being pushed off of" something. Friction... well it gets in the way of things.
 
  • #8
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ZapperZ said:
Hold a ball while standing on skates on ice. Now throw the ball in one direction. You will see that you will move in the opposite direction. This is conservation of linear momentum. The volume of gasses escaping from jet engines and rocket nozzles do just that.

Zz.
Or have you and your friend on roller skates, and push off him/her. You will find that you both move in opposite directions. It will not make much difference how far you travel if you coat your hands in vaseline or with sandpaper gloves.

You've probably seen speakers, when turned up loud enough, that the membrane moves back and forth considerably. On the inside, there is no friction going on to move that. It is moved by magnetism.
 

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