Space Travel: How Do Spaceships Move?

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Discussion Overview

The discussion revolves around the mechanics of how spaceships move in the vacuum of space, focusing on the principles of motion and propulsion without the presence of friction. Participants explore concepts related to Newton's laws of motion and the conservation of momentum.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that all movement relies on friction or pushing off something, questioning how spaceships operate without these forces.
  • Another participant explains that a spaceship moves according to Newton's first law and changes direction or accelerates by expelling mass in the opposite direction, referencing the conservation of linear momentum.
  • A different participant elaborates that the propulsion of a spaceship is due to the expulsion of gases from its exhaust, invoking Newton's third law regarding equal and opposite reactions.
  • Some participants express confusion about the lack of a surface to push against in space, reiterating concerns about the role of friction in movement.
  • One participant uses the analogy of throwing a ball while on skates to illustrate conservation of momentum, emphasizing that the action of expelling gases propels the rocket.
  • Another participant reinforces the analogy by suggesting that similar principles apply when pushing off another person on roller skates, further explaining the concept of momentum transfer.
  • Additional analogies are introduced, such as the movement of speaker membranes, to illustrate motion without friction.

Areas of Agreement / Disagreement

Participants generally agree on the principles of Newton's laws and conservation of momentum but express differing levels of understanding regarding the implications of these principles in the context of space travel. Some confusion remains about the absence of a medium to push against, indicating unresolved conceptual challenges.

Contextual Notes

Some participants' statements reflect assumptions about the nature of friction and its role in movement, which may not be universally accepted. The discussion does not resolve the conceptual challenges related to the lack of a pushing surface in space.

Who May Find This Useful

This discussion may be of interest to individuals exploring the fundamentals of physics, particularly those curious about motion in space and the principles governing propulsion systems.

Tido611
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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 I am over looking somthing very obvious but I am just not sure what it is.
 
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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.
 
For example, the reason a spaceship would fly is basically its firing mass out of its exhaust and according to Newton's "Equal and opposite reaction" (forget the #... god I am 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.
 
ok i already understood what you guys are saying but i can't 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.
 
Tido611 said:
ok i already understood what you guys are saying but i can't 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.
 
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!
 
Tido611 said:
ok i already understood what you guys are saying but i can't 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 isn't "being pushed off of" something. Friction... well it gets in the way of things.
 
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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