Can a Vacuum in Space Create Drag on Moving Objects?

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Discussion Overview

The discussion revolves around the concept of drag in a vacuum, particularly whether a vacuum in space can create drag on moving objects. Participants explore the mechanics of force application in a vacuum, the principles of rocket propulsion, and the interactions between objects in space.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question whether a vacuum can create drag on objects moving through it, suggesting that space cannot be mechanically interacted with like a gas.
  • Others argue that while a vacuum does not provide drag, forces can still be applied in space, as demonstrated by rocket propulsion.
  • One participant claims that throwing an object in a vacuum would not result in the object moving away due to the equal and opposite reaction, which is challenged by others who assert that the forces do not cancel out as they act on different bodies.
  • There is a discussion about the mechanics of rockets, with some participants asserting that the mass flow of exhaust gases is what propels the rocket, while others question how this can occur without resistance in a vacuum.
  • Some participants introduce the concept of effort and resistance forces, debating their relevance in the context of rocket propulsion and motion in a vacuum.
  • One participant compares the operation of a rocket to that of a gun, questioning how the rocket can function without a second body to push against, while others clarify that the exhaust itself provides the necessary interaction.
  • Concerns are raised about the necessity of resistance for forces to do work, with some participants asserting that forces can still act in a vacuum without traditional resistance.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of drag in a vacuum or the mechanics of force application in space. Multiple competing views remain regarding the role of resistance and the functioning of rockets in a vacuum.

Contextual Notes

Participants express uncertainty about the definitions and implications of resistance and effort forces in the context of motion in a vacuum. The discussion includes various assumptions about the mechanics of force interactions that are not fully resolved.

  • #61
im not talking about here on Earth I am talking about in a perfect weightless vacuum...

: If there were no gravity, and if the air did not impede the motion of bodies, then anybody will continue its given motion with uniform velocity in a straight line.
: Every body under the sole action of its innate force moves uniformly in a straight line indefinitely unless something extraneous hinders it.
: Every body perseveres in its state of being at rest or of moving uniformly straight forward except insofar as it is compelled to change its state by forces impressed.

what is an impressed force...This force consists in the action only, and remains no longer in the body when the action is over. For a body maintains every new state it acquires by its inertia only. But impressed forces are of different origins, as from percussion, from pressure, from centripetal force.

impressed forces are of different origins, as from percussion, from pressure, from centripetal force.

so me throwing anything in space vacuum would result in the impressed forces from pressure of my arm and equal and opposite force applied to the object and both the object and me will move away from each other and then back toward each other simultaneously...canceling each others impressed forces so no movement will occur
 
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  • #62
Newtonforce said:
so me throwing anything in space vacuum would result in the impressed forces from pressure of my arm and equal and opposite force applied to the object and both the object and me will move away from each other and then back toward each other simultaneously...canceling each others impressed forces so no movement will occur

So what is your response to my scenarios with the ball and the slingshot above?
 
  • #63
imstill finding my feet ...but its definatley probable that rockets cannot propell them selves in a space vacuum...by recoil alone...force impressed on rocket chamber are simultaneously moving against and away from rocket chamber... The reciprocal of 0 force is 0 force. The equal and opposite reaction to 0 would be 0.
 
  • #64
Newtonforce said:
im not talking about here on Earth I am talking about in a perfect weightless vacuum..
OK.

Newtonforce said:
: If there were no gravity, and if the air did not impede the motion of bodies, then anybody will continue its given motion with uniform velocity in a straight line.
: Every body under the sole action of its innate force moves uniformly in a straight line indefinitely unless something extraneous hinders it.
: Every body perseveres in its state of being at rest or of moving uniformly straight forward except insofar as it is compelled to change its state by forces impressed.
OK.

Newtonforce said:
what is an impressed force...This force consists in the action only, and remains no longer in the body when the action is over.
"impressed" force is just any external force acting on an object. And yes, as soon as you remove it, it no longer acts on the body.

Newtonforce said:
so me throwing anything in space vacuum would result in the impressed forces from pressure of my arm and equal and opposite force applied to the object and both the object and me will move away from each other
You throwing your shoe in space would have you exerting a force on the shoe and the shoe exerting a force on you. You both accelerate and move away from each other. As soon as you break contact you no longer exert forces on each other, you just keep on moving at constant velocity.

Newtonforce said:
and then back toward each other simultaneously.
Why is that?
 
  • #65
Newtonforce said:
The reciprocal of 0 force is 0 force. The equal and opposite reaction to 0 would be 0.
Why do you keep repeating this strange mantra?

I could just as easily say: The equal and opposite reaction to 10 N of force is 10 N of force. So?
 
  • #66
stored energy in the rubber will move the ball as far as the rubber band will recoil ...what has been impressed onto the ball that the ball did not impress back to the rubberband
The reciprocal of 0 force is 0 force. The equal and opposite reaction to 0 would be 0.
 
  • #67
Newtonforce said:
but its definatley probable that rockets cannot propell them selves in a space vacuum
Seriously?
 
  • #68
.force impressed on rocket chamber are simultaneously moving against and away from rocket chamber...
 
  • #69
Newtonforce said:
stored energy in the rubber will move the ball as far as the rubber band will recoil ...what has been impressed onto the ball that the ball did not impress back to the rubberband
The reciprocal of 0 force is 0 force. The equal and opposite reaction to 0 would be 0.

So you're pulling the rubber band back, the pebble along with it. You let go of the rubber band and it propels itself and the pebble forward. The rubber band eventually stretches forward to a point where it cannot go further forward. This is what happens on Earth and in space.

But now you say that things start to differ at this point. You're saying that now the pebble will stick to the rubber band in space and go no further than the rubber band while on Earth the pebble will detach itself form the rubber band and keep moving forward. Correct?

The reason I am doing this is to illustrate (hopefully to you!) that there are some seriously bizarre consequences that come from your model.
 
  • #70
how can motion be achieved by a balanced equation...there has to be a differential between the interior and the exterior...
 
  • #71
Again and again, you still don't understand Newton's 3rd law. There is nothing more to say.
 
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  • #73
I think this thread has run its course. @Newtonforce: Please read up on Newton's 3rd law.
 
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