Firing a bullet from a gun in a gravity well.

1. Jul 5, 2011

yuiop

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?

Last edited: Jul 5, 2011
2. Jul 5, 2011

bcrowell

Staff Emeritus
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.

3. Jul 5, 2011

PAllen

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