1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Using e=mc^2 to calculate electrical properties

  1. Oct 10, 2009 #1
    from rearranging e=mc^2 i got time equivalent to (kg m^2/(A V) (kilogram meter squared per ampere volt))^(1/3)

    so if i have a material that is 1kg, 1m long, has 1amp, and 1volt, what does the time attribute mean? is that the amount of time it takes an electron to travel from one end of the object to the other?
     
  2. jcsd
  3. Oct 10, 2009 #2

    Pengwuino

    User Avatar
    Gold Member

    Rearranging units randomly in this fashion is meaningless. Where do you even get the 't' from? the speed of light?
     
    Last edited: Oct 10, 2009
  4. Oct 10, 2009 #3

    russ_watters

    User Avatar

    Staff: Mentor

    That's not re-arranging equations, it is rearranging units! You can rearrange equations - you can't rearrange units.
     
  5. Oct 10, 2009 #4

    Pengwuino

    User Avatar
    Gold Member

    But Russ, I did say units..... *whistles innocently*
     
  6. Oct 11, 2009 #5
    _why_ can't you do that though? Obviously that cluster of units together has some sort of significance. For some reason 1 (kg m^2/(A V) (kilogram meter squared per ampere volt))^(1/3) is equal to 1 second. All I am wondering is why?
     
  7. Oct 11, 2009 #6

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    Because this is physics, not mathematics.

    Each of those quantities have a physical significance. You can't simply manipulate those symbols without understanding the physics behind those manipulation. If you do that, you'll get absurd results.

    For example, look at the units for torque, and for work done. If you simply put blinders on and forget about the physical meaning of each of those, and pay attention only to their dimensions, you'll think that they are the same thing. They are not.

    Zz.
     
  8. Oct 11, 2009 #7
    Who said those were absurd results? that seems like its a perfectly normal result. I guess my question is, what _are_ the physics behind that equation?
     
  9. Oct 11, 2009 #8

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    The "time" factor in your original question is the "result".

    Maybe you should have asked that first, and then, after understanding that, go on to the next step. Without that first step, you risk doing something based on either faulty or incomplete knowledge.

    E=mc^2 has been discussed ad nauseum on here (look in either the Quantum Physics or the Relativity forums), and in many reputable websites. Try starting there first and see if there is anything you do not understand that we can try to clarify on here. That's the best way to learn something new, which is to try and understand it yourself first and then get some help in figuring out what you find puzzling or confusing.

    Zz.
     
  10. Oct 11, 2009 #9

    russ_watters

    User Avatar

    Staff: Mentor

    Everyone who has responded so far!
    If it were a normal result, then the question would not need to be asked.
    I'm sorry, but as already said, there are none.
     
  11. Oct 11, 2009 #10

    Pengwuino

    User Avatar
    Gold Member

    Yes, you have to know what the equation means. Think about a blind treatment in this fashion. The energy an object has is [tex]E = \frac{mv^2}{2}[/tex]. Oh but the energy is also [tex]E = mc^2[/tex]. So does [tex] c^2 = \frac{v^2}{2}[/tex] mean anything?
     
  12. Oct 12, 2009 #11
    does it? I mean they have to have _some_ sort of significance together otherwise we would never end up in that combination.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Using e=mc^2 to calculate electrical properties
  1. Meaning of E=mc^2 (Replies: 5)

  2. Playing with E=MC^2 (Replies: 3)

  3. E=MC^2 Question (Replies: 2)

Loading...