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Firing a bullet from a gun in a gravity well.

  1. Jul 5, 2011 #1
    Let's say we have gun that fires a bullet at 1000 m/s horizontally when high up in a gravitational potential.

    Now we take the gun deeper into the gravitational well to a point where the gravitational redshift factor is higher by a factor of 4. Will the muzzle velocity be the same, faster or slower as measured by a local observer?

    THis is related to another thread (https://www.physicsforums.com/showthread.php?t=511699).
    Last edited: Jul 5, 2011
  2. jcsd
  3. Jul 5, 2011 #2


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    If the gun is free-falling, and the observer free-falling with it, then the muzzle velocity is the same. This is just the equivalence principle. Locally, space always has the same properties.

    If the gun isn't free-falling, then the answer could be different for trivial reasons. E.g., the gun might be instantly crushed by the gravitational field.
  4. Jul 5, 2011 #3


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    Or a little less extreme, the bullet would have substantial, asymmetric, friction against the barrel.
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