Size of Bullet Hole: Comparing 0.000001c & .9c

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Discussion Overview

The discussion revolves around the effects of relativistic speeds on the size of bullet holes created by two bullets traveling at different velocities (0.000001c and 0.9c) through a tin foil target. Participants explore the implications of special and general relativity on the dimensions of the bullet holes, considering assumptions about the motion and properties of the bullets and target.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant posits that both bullets will create holes of the same size, assuming they travel perpendicular to the target.
  • Another participant questions whether the diameter of the bullet changes due to relativistic effects, asserting that length contraction occurs only along the direction of movement.
  • A different viewpoint suggests that the requirement for the target to have no component of velocity perpendicular to that of the bullet may affect the size of the hole, potentially elongating it depending on the bullet's length in the rest frame of the foil.
  • One participant expresses confusion regarding the application of general relativity versus special relativity in this context, indicating a lack of clarity on the original question's intent.
  • Another participant notes that modeling the scenario with general relativity would require complex computations beyond the scope of the discussion.

Areas of Agreement / Disagreement

Participants generally agree that if the bullets are traveling perpendicular to the target, the holes should be the same size. However, there is disagreement regarding the implications of different frames of reference and whether the assumptions made about the motion and relativistic effects are correct.

Contextual Notes

There are limitations in the assumptions made regarding the interaction between the bullets and the target, particularly concerning the application of general relativity versus special relativity and the conditions under which the bullet holes are analyzed.

sqljunkey
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If I had two bullets one moving 0.000001 c and the other moving at .9 c for example, and they both went thru a tin foil square target, assuming they are traveling in vacuum, and that the tin foil square target will make a perfect aperture around the radius of the passing bullet, assuming the bullet is cylindrical in shape, which bullet hole would be the bigger one?

Here I'm assuming there are only two objects (with masses) in the spacetime, and I'm assuming that the principles of general relativity apply.
 
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sqljunkey said:
If I had two bullets one moving 0.000001 c and the other moving at .9 c for example, and they both went thru a tin foil square target, assuming they are traveling in vacuum, and that the tin foil square target will make a perfect aperture around the radius of the passing bullet, assuming the bullet is cylindrical in shape, which bullet hole would be the bigger one?

Here I'm assuming there are only two objects (with masses) in the spacetime, and I'm assuming that the principles of general relativity apply.
The holes would be the same size.
 
sqljunkey said:
If I had two bullets...
Are you trying to ask whether the diameter of the bullet changes? If so, the answer is no. Length contraction is along the direction of movement.
 
As long as the bullets are traveling perpendicular to the target, the holes should be the same size.
 
pervect said:
As long as the bullets are traveling perpendicular to the target,
Good point, but is this restriction the correct one? Isn't the requirement that the target have no component of velocity perpendicular to that of the bullet? If that is not the case then the bullet hole would be elongated slightly due to the lateral motion - and this would depend on the length of the bullet in the rest frame of the foil.

Or am I misreading you?
 
He says GR, not SR. As such, I have no idea what he's getting at.
 
sqljunkey said:
I'm assuming there are only two objects (with masses) in the spacetime, and I'm assuming that the principles of general relativity apply.

If you are trying to actually model this scenario as the bullet and the foil having enough stress-energy to curve spacetime, sorry, that's way beyond what we can do here. You need a supercomputer and a lot of time.

If you really meant special relativity, i.e., you are fine with spacetime being flat and you are just asking what the Lorentz transformation says about your question, you already have been given the answer in this thread.

In either case, it is time to close this thread.
 

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