The movie wanted defies physic.

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Discussion Overview

The discussion revolves around the portrayal of bullet trajectories in the movie "Wanted," specifically the concept of curving bullets. Participants explore the physical principles that govern projectile motion, including the effects of forces like gravity and air resistance, as well as the implications of the Magnus Effect. The conversation touches on theoretical and conceptual aspects of motion and centripetal force.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that a bullet cannot curve due to the laws of motion, comparing it to a sling where the trajectory is always a straight line without external forces.
  • Another participant questions the forces acting on the bullet after it leaves the gun, identifying gravity and air resistance as primary factors.
  • It is noted that inertia plays a role, as there are no external forces acting on the bullet once it exits the barrel, supporting the idea that the trajectory remains straight.
  • A participant mentions that while air resistance slows the bullet and gravity pulls it down, the bullet cannot curve unless external forces act upon it.
  • Some participants discuss the potential for a bullet to curve if the axis of its spin is misaligned with its direction of flight, suggesting that this could complicate the trajectory.
  • One participant introduces the Magnus Effect, indicating that it could influence the flight of spinning projectiles, though it does not allow for shooting around corners.
  • Another participant reiterates the idea that the bullet is unlikely to tumble within the first 50 meters due to rifling, but questions the movie's depiction of immediate curving after firing.
  • A later reply references the Magnus Effect in relation to missiles, suggesting that the movie may exaggerate its impact on bullets.

Areas of Agreement / Disagreement

Participants generally agree on the fundamental principles of projectile motion and the role of forces like gravity and air resistance. However, there is no consensus on the extent to which the Magnus Effect could allow for curving trajectories, and the discussion remains unresolved regarding the feasibility of curving bullets as depicted in the movie.

Contextual Notes

Some limitations include the need for quantitative analysis of the Magnus Effect and the conditions under which a bullet might tumble in flight, which are not fully explored in the discussion.

David Yu
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In the movie wanted, the characters inside the movie can curve bullets by swinging the pistol, it is obvious it defies the law of physics. I know that a bullet cannot curve due to the law of motion, it is the same a sling (the thing that throw rocks) where the trajectory will always be a straight line, without Earth's gravity.
Can someone tell me exactly why it is impossible, using motion and centripetal force.
 
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What are the forces on the bullet after it's left the gun?
 
Gravity down, (some air resistance)
 
So the bullet trajectory doesn't curve because...
 
inertia, where there is no external force acting on it after it leaves the barrel.
 
Yes. Newton's First Law, in short.

The bullet slows because of air resistance and falls because of gravity, but there are no other forces. Other than "up and over" artillery fire (curve due to gravity), you can't hit anything you don't have a straight line shot at.

I suppose by flicking the barrel sideways you could make the bullet come out ever so slightly on the diagonal, but it would be easier to just point the gun at the target. There is also a subtle interaction between a spinning sphere or cylinder and the air called the Magnus Effect (which I only learned about just now myself), which affects bullet flight. It still doesn't let you shoot round corners by turning your gun barrel.
 
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David Yu said:
Gravity down, (some air resistance)

If the shooter can manage to send the bullet on a trajectory where the axis of the spinning bullet isn't aligned with the direction of flight, there could be curving effect. So to have an "air tight" argument against a trajectory curving sideways you'd have to consider that effect quantitatively. If the bullet begins to tumble in flight, the trajectory could get very complicated.
 
Stephen Tashi said:
If the shooter can manage to send the bullet on a trajectory where the axis of the spinning bullet isn't aligned with the direction of flight, there could be curving effect. So to have an "air tight" argument against a trajectory curving sideways you'd have to consider that effect quantitatively. If the bullet begins to tumble in flight, the trajectory could get very complicated.
the bullet most likely will not tumble in the first 50 m at least, thanks to the rifling, the movie has shown that it begun to curve right after it has fired.
 

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