Notices
Results 1 to 12 of 12

Thread: Forces over distance

  1. #1 Forces over distance 
    New Member
    Join Date
    Oct 2008
    Posts
    4
    I have some trouble understanding how a force such as gravity can work over a distance - not even needing a medium, because it works just as well in a vacuum like space. Can somebody try explaining how gravitation is able to "reach out" the way it does?

    I know that Einstein's way of describing gravity involves the curvature of the entire space-time continuum. I guess he has in a way solved the force over distance mystery for gravity, but what about a magnetic force?


    I will question all your answers
    Reply With Quote  
     

  2.  
     

  3. #2  
    Forum Sophomore Tharghana's Avatar
    Join Date
    Oct 2008
    Location
    Canada
    Posts
    157
    I believe gravity's attraction, spreads out in a similar matter as light.

    The Gravity attracts things from every direction of the center of its soruce, the further away the hold becomes less.

    Its hard to explain how it moves through the Vacuum since we don't really know what Gravity is, just what its effects are.


    www.periodicvideos.com - A Great Site

    "Well, good chemists shouldn't lick their fingers, anyways." - Martyn Poliakoff

    "You have lived to die, and your running out of life."

    "Once and a while, I go out of my way... to kill you... a little"
    Reply With Quote  
     

  4. #3  
    Forum Bachelors Degree Demen Tolden's Avatar
    Join Date
    Sep 2007
    Location
    St. Paul, Minnesota, USA
    Posts
    475
    Quote Originally Posted by Waldheri
    I have some trouble understanding how a force such as gravity can work over a distance
    Your initial statement is confusing because the definition of work in physics is force applied over a distance. This equation represents work:

    where W is work, F is force, d is distance, and theta is the angle between the direction the force is applied and the direction the object travels.

    Quote Originally Posted by Waldheri
    not even needing a medium
    What do you mean by a medium? What is a medium?

    Work done by gravity can be represented with the equation:

    where is the work done by gravity, m is the mass of the object on which gravity is acting on, g is the acceleration of gravity (about 9.8 meters per second for us Earthlings), and d is the distance in which the object travels while gravity is acting on it. Theta is once again the angle between the direction the gravitational force is acting on the object and the direction the object actually travels.

    I know this is way off topic, but I think its funny how work and mgd can be associated together in more ways than physics.
    The most important thing I have learned about the internet is that it needs lot more kindness and patience.
    Reply With Quote  
     

  5. #4  
    New Member
    Join Date
    Oct 2008
    Posts
    4
    I'm sorry, I can understand why you're confused. I did not mean "work" as force applied over distance, but rather work as in "how can it be so".

    With a medium, I meant a substance through which something is achieved. Example: sound needs a medium. I know that a force and a sound are completely different things, but the fact remains that because of some mystery, a force can enact an acceleration on an object that is not mechanically connected to the object from which the force is exerted.
    I will question all your answers
    Reply With Quote  
     

  6. #5  
    Forum Sophomore Tharghana's Avatar
    Join Date
    Oct 2008
    Location
    Canada
    Posts
    157
    I would like to know how you can Quote things I never said :?, Walderi said those things
    www.periodicvideos.com - A Great Site

    "Well, good chemists shouldn't lick their fingers, anyways." - Martyn Poliakoff

    "You have lived to die, and your running out of life."

    "Once and a while, I go out of my way... to kill you... a little"
    Reply With Quote  
     

  7. #6  
    Forum Bachelors Degree Demen Tolden's Avatar
    Join Date
    Sep 2007
    Location
    St. Paul, Minnesota, USA
    Posts
    475
    Sound is created through energy in a collision which is not perfectly elastic. I had made another post just a few days ago talking the two different types of collisions, so I'll just summarize a bit and describe where energy fits in to it.

    In all collisions that occur between all objects, momentum is conserved. What this means is that the momentum before the collision equals the momentum after the collision. Momentum is the product of mass and velocity.

    In a perfectly elastic collision, kinetic energy is conserved. This means that the kinetic energy that occurs before a collision is equal to the kinetic energy after a collision. We could restate this by saying that no energy was lost in the collision of these objects. As previously stated, sound takes energy to create. Heat also takes energy to create. There may be other possible things that could happen during the collision that takes energy to occur. In a perfectly elastic collision, these things do not occur, because ALL the energy is conserved. In a perfectly elastic collision, there is no sound, no heat. Two objects collide and go their seperate ways.

    In a partially inelastic collision, kinetic energy is not conserved. This means that some of the energy that went into the collision is lost by the creation of sound or heat or whatever.

    So at this point we have established the link between sound and energy. Now we can establish the link between energy and force.

    Work is equal to the change of kinetic energy over a specified period of time. We can represent this relationship with the following formula:

    Using the formula I stated in my previous reply, we can subsitute for W and create the following formula:


    So yes indeed sound is related to force.

    (Sorry Tharghana for making that mistake. I fixed the quotes to make them less confusing.)

    So Waldheri, you are saying that it is interesting that gravity can perform work (I'm using the physics definition here) on an object while, at the same time, gravity is not a solid object?
    The most important thing I have learned about the internet is that it needs lot more kindness and patience.
    Reply With Quote  
     

  8. #7  
    Forum Sophomore
    Join Date
    May 2008
    Posts
    121
    It is unknown precisely how this happens, but the particle theorized to mediate the force is the graviton.

    For the electromagnetic force, it is the photon that is the boson.

    I apologise for the jargon on the link. I explained briefly the attraction between an electron and a positron already:
    Attraction is caused by the exchange of gauge bosons. The gauge boson for electromagnetism is the photon.

    The simplest example is an electron being attracted to a positron. As the electron approaches the positron, it emits a photon in the opposite direction to the positron. The momentum carried away by the photon causes the electron to move towards the positron.

    Now, at this scale Heisenbergs uncertainty principle comes into play. As the momentum is defined by some degree of accuracy, there is uncertainty as to where the perticle actually is. As a result of this, the same photon actually hits the positron from behind, and causes it also to move towards the electron.
    Reply With Quote  
     

  9. #8  
    New Member
    Join Date
    Oct 2008
    Posts
    4
    Edit: This post was intended for Demen Tolden. Stuart Thomson, who was quicker to respond, seems to have understood my question better.

    No, you have just wasted your time talking about energy and collisions. This is not what I'm talking about. Let's try to rephrase my question:

    How can a force (such as gravity) from object A bring about an acceleration on an object B that is not mechanically connected to object A?

    Similarly:

    How can an electromagnetic force repel or attract electrically charged particles A and B away from/to each other without these objects being connected?
    I will question all your answers
    Reply With Quote  
     

  10. #9  
    New Member
    Join Date
    Oct 2008
    Posts
    4
    Sorry for the double post, but for clarity's sake I thought I'd better reply in a separate message

    Stuart Thomson, are there also bosoms theorized for the other fundamental forces? Furthermore, how does the graviton fit in Einstein's curved space-time? Or is this actually one of the main questions physicists have been asking themselves in trying to tie together quantum theory and Einstein's relativity in a grand unification theory?
    I will question all your answers
    Reply With Quote  
     

  11. #10  
    Forum Bachelors Degree Demen Tolden's Avatar
    Join Date
    Sep 2007
    Location
    St. Paul, Minnesota, USA
    Posts
    475
    Quote Originally Posted by Waldheri
    How can a force (such as gravity) from object A bring about an acceleration on an object B that is not mechanically connected to object A?
    What you describe here is a collision whether the two objects are connected or not. This is still a collision if the objects never make contact.

    Quote Originally Posted by Waldheri
    How can an electromagnetic force repel or attract electrically charged particles A and B away from/to each other without these objects being connected?
    This is also a collision using physics terminology.
    The most important thing I have learned about the internet is that it needs lot more kindness and patience.
    Reply With Quote  
     

  12. #11  
    Forum Sophomore
    Join Date
    May 2008
    Posts
    121
    Quote Originally Posted by Waldheri
    Sorry for the double post, but for clarity's sake I thought I'd better reply in a separate message

    Stuart Thomson, are there also bosoms theorized for the other fundamental forces? Furthermore, how does the graviton fit in Einstein's curved space-time? Or is this actually one of the main questions physicists have been asking themselves in trying to tie together quantum theory and Einstein's relativity in a grand unification theory?
    Yes gauge bosons have been found for 3 of the four fundamental forces (The graviton has not been found). The weak force has the , and the Z, the electromagnetic force has the photon, and the strong force has gluons. Yes unifying general relativity and the standard model is one of the biggest problems facing modern physics. http://en.wikipedia.org/wiki/Quantum_gravity
    Reply With Quote  
     

  13. #12  
    Suspended
    Join Date
    Apr 2008
    Posts
    2,176
    Quote Originally Posted by Waldheri
    I'm sorry, I can understand why you're confused. I did not mean "work" as force applied over distance, but rather work as in "how can it be so".

    With a medium, I meant a substance through which something is achieved. Example: sound needs a medium. I know that a force and a sound are completely different things, but the fact remains that because of some mystery, a force can enact an acceleration on an object that is not mechanically connected to the object from which the force is exerted.

    All particles, any communication, needs a medium (A substance to travel through)by actual demonstration of the workings of the universe. Nothing anywhere at any time has ever been communicated by anything but atoms, matter. There is only 100 percent proof of this so far.

    The reason we cannot see anything beyond the edges of our universe was speculated by Universal Scientists, that the edges of the universe are not made of atoms of gas. But rather free electrons, that do not communicate, the velocity and information of electrons from outside the universe, if there is anything outside the universe.

    Light, radio, x-rays, Ultraviolet, sound all require matter to travel through. I don't believe anyone has ever disputed this with any experiment on record.

    Sincerely,


    William McCormick
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •