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What is the deal with kinetic and potential energy, electricity and magnetism

  1. Sep 19, 2012 #1
    Hello,
    Firstly i am new here ( not offering an excuse) and an on and off lurker to this awesome forum. I am trying my best to fit into the established rules ,sorry if i broke any inadvertently.

    If kinetic and potential energy represent the same things why are there entities representing the same thing and the same with electric and magnetic forces.

    Is there any explicit reason other than " conservation of energy" and/or "depends on which one you end up using by virtue of your point of view/interest" to use what looks like redundant quantities for representing the same entity.

    Also last question: what exactly does kinetic and potential energy as a whole try to represent analogously what does electric and magnetic forces as a whole try to represent ??
     
  2. jcsd
  3. Sep 20, 2012 #2
    Do you really think that we would make such progress in physics if we didn't distinguish between P. and K. energy, and between electric and magnetic force? Don't you think our analytic powers would be significantly reduced?
    As for your last question, kinetic and potential energy as a whole represent mechanical energy, and electric and magnetic forces as a whole represent electromagnetic force.
     
  4. Sep 21, 2012 #3
    Hi!

    Obviously there are reasons why they are separated as different entities. Take this for an example, an object that is high in the ground, has high potential energy and when it goes down, kinetic energy increases while the other decreases. This highly contributes to the application of vast industries. Roller coasters? Check. Land development? Check. Rocket launching? Check! All have to be referred to this concept (and others too of course) to ensure safe and smooth operation.

    As for electricity and magnetism, well, electricity induction is one primary subject to be focused on. Electricity can be produced just by using the Earth's North-South polarity. More applications to come.

    As you can see, these diversions let scientists and engineers to work much easier than compiling them into one. It's just logic. 2 different things. Duality must exist.

    Cheers!
     
  5. Sep 25, 2012 #4
    Hello thanks to both for the answers.
    So the main point here being analysys and duality ??

    So induction is how energy transfer occurs ( even in static electric fields ??) so if induction helps in energy transfer then why the need for both electric and magnetic fields ( all this time i had thought magnetic field is the one that transfers energy and hence there is no transfer of energy in static electric fields, also because i have read that magnetic field is caused by flowing electric charges this point was reinforced albeit skewedly.

    Thanks
    ~
     
  6. Sep 25, 2012 #5
    I don't understand the question. I don't actually think many of your premises are correct... kinetic and potential energy aren't the same, nor are the electric and magnetic forces.

    Is there a way you can rephrase the question without using ambiguous terms like "entity"?
     
  7. Sep 25, 2012 #6
    Instead of saying a body has X amount of mechanical energy why do people say it has nx Potential energy and (1-nx) Kinetic energy or viceversa.

    Arent electric and magnetic forces the same ( i remember reading that they are like 2 sides of the same coin).

    Regards,
    ~
     
  8. Sep 25, 2012 #7
    1st q: Because the mechanical energy is defined as the sum of kinetic and potential energy. That's a useful definition because the sum will remain constant under certain assumptions.

    2nd q: They are linked, in a way that they cannot be separated into two different and unrelated forces, but they are certainly not the same.
     
  9. Oct 6, 2012 #8
    @ Mikey thanks for the reply, i have some more questions.
    But both are quantified by photons ??

    What are the practical implication of "there cant be magnetic monopoles" on both electric and magnetic fields existing in a manner in which they cant be separated.
     
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