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Geodesic and inertial frame

  1. Aug 17, 2009 #1

    I was wondering: i'm sitting at my desk and on my desk lies a pen. Does the pen describe a geodesic? And is the room i'm sitting in an inertial frame?

    I think the pen doesn't describe a geodesic because it's not in free fall and i think my room is a good approximation of an inertial frame for things that happen in my room.

    Am i right? Thanks!
  2. jcsd
  3. Aug 17, 2009 #2
    No. If the desk wasn't there, then for a few seconds the pen would describe a geodesic. Similarly, your room is no better inertial frame than an elevator.
  4. Aug 17, 2009 #3


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    Your room would be a good approximation for the frame of a room undergoing constant 1G acceleration through space in special relativity.
  5. Aug 18, 2009 #4
    So, in practice, only when an object is in free fall, we know it describes a geodesic.

    Thanks for the answers!
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