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Thread: Pull?

  1. #1 Pull? 
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    All things that move need a pressure to make them move, all pressure requires a pushing force, so therefore "pull" is not force in its self?


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  3. #2  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by GazLee View Post
    All things that move need a pressure to make them move
    No. Force is required not pressure.
    all pressure requires a pushing force
    That's a sloppy way of expressing it. Pressure is force per unit area: no force, no pressure.
    so therefore "pull" is not force in its self?
    Wrong.


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  4. #3  
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    There has to be a pressure (push) to start anything to move, so "pull" is not a force.
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  5. #4  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by GazLee View Post
    There has to be a pressure (push) to start anything to move
    No.
    There has to be an applied force. It needn't be a push.
    , so "pull" is not a force.
    This is incorrect.
    Where is the "push" applied when a trailer is towed?
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  6. #5  
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    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by GazLee View Post
    There has to be a pressure (push) to start anything to move
    No.
    There has to be an applied force. It needn't be a push.
    , so "pull" is not a force.
    This is incorrect.
    Where is the "push" applied when a trailer is towed?
    The push comes from the tower. Like if you want to pull something like a rope, you're hand needs to push down on the rope creating pressure.
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  7. #6  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by GazLee View Post
    The push comes from the tower.
    I get it. You can push something from in front.
    Like if you want to pull something like a rope, you're hand needs to push down on the rope creating pressure.
    And that only applies a "push" to the rope.
    The rope then pulls on the towed object.
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  8. #7  
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    Quote Originally Posted by GazLee View Post
    Quote Originally Posted by Dywyddyr View Post
    Quote Originally Posted by GazLee View Post
    There has to be a pressure (push) to start anything to move
    No.
    There has to be an applied force. It needn't be a push.
    , so "pull" is not a force.
    This is incorrect.
    Where is the "push" applied when a trailer is towed?
    The push comes from the tower. Like if you want to pull something like a rope, you're hand needs to push down on the rope creating pressure.
    If you have a loop in the end of the rope you just link your hand through it and then you don't need to push on anything. A rope is actually a perfect example of something that exerts a force by pulling. Something pulls the rope and it goes tight due to the force of tension in it, as it pulls whatever the object is. The tension in the cables is what enables a suspension bridge to hold up the roadway.

    Where you have a point is, going back to your pressure idea, that when vacuum cleaner "sucks" up dust, it does not pull on it. It just takes away the atmospheric pressure that is normally exerted from all sides on objects, and that pressure imbalance is what causes the dust to move into the suction tube.
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  9. #8  
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    Try moving anything without a pushing pressure, "pulling" is a description of the action. You need to add pressure inside the loop, in order for the "pull" to take place.
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  10. #9  
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    Quote Originally Posted by GazLee View Post
    Try moving anything without a pushing pressure, "pulling" is a description of the action. You need to add pressure inside the loop, in order for the "pull" to take place.
    If all you mean is that any pull involves a push (part of the rope is pushing against part of the loop when the cart is being pulled) then that’s another topic for debate. In physics “a force is any interaction that, when unopposed, will change the motion of an object”.1 And “pulling the cart” simply means that the vector of the applied force of “that small portion of rope against that small portion of the loop” is aimed away from the cart as opposed to being aimed towards it.


    1 https://en.wikipedia.org/wiki/Force [my emphasis]
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  11. #10  
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    "Pull" is the result of a pushing force, "pull" itself is not a force.
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  12. #11  
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    Quote Originally Posted by GazLee View Post
    "Pull" is the result of a pushing force, "pull" itself is not a force.
    Repeating an incorrect (and unsupported) claim does not make that claim valid.

    Moved to Pseudo.
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  13. #12  
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    I don't see what is hard to understand here, something has to push against whatever is being "pulled" at the very source, nothing moves without pressure and you cannot have pressure without a pushing motion. Try it yourself.
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  14. #13  
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    Quote Originally Posted by GazLee View Post
    I don't see what is hard to understand here
    Me neither, but you're having quite a bit of difficulty anyway, aren't you?
    something has to push against whatever is being "pulled" at the very source
    Wrong. As has been pointed out.
    nothing moves without pressure
    Wrong. As has been pointed out.
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  15. #14  
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    Quote Originally Posted by GazLee View Post
    "Pull" is the result of a pushing force, "pull" itself is not a force.
    Or, “pull” is just a series of contact forces in which the final one has an applied vector away from the object moved, and the particle of speech “‘pull’ itself” is meaningless.
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  16. #15  
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    I've had the same idea that pulls do not exist as forces, that they are really pushes in disguise (for example, pulling on a door is really pushing the handle/knob towards you).
    If we define "push" as exerting a force in the opposite direction from yourself and "pull" as exerting a force in the direction of yourself, then gravity is always a pull, as well as electric forces between opposite charged objects.
    In the case of a trailer, the net force on the trailer from the rope is in the direction of the rope, so is a pull. But the end of the rope is pushing on the hook of the trailer.
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  17. #16  
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    Quote Originally Posted by GazLee View Post
    I don't see what is hard to understand here, something has to push against whatever is being "pulled" at the very source, nothing moves without pressure and you cannot have pressure without a pushing motion. Try it yourself.
    Newton's Third tells us that every "push" is matched by a "pull".

    Or, to put it another way, you are just playing with words. This has nothing to do with science.
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