Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Bullet Trajectories
Name: Riad S.
Status: other
Age: 20s
Location: N/A
Country: N/A
Date: 2001-2002


Question:
My coworkers and I are disputing the trajectory of a bullet. If I was to shoot a bullet with the gun barrel horizontal, when the bullet comes to rest, will it land directly in line with the barrel or would it be slightly to the left or slightly to the right of the barrel? To make sure there is no confusion, we are assuming there is no wind at all. From my knowledge, the bullet rotates clockwise out of the barrel and my assumption is that it will land to the left.


Replies:
Hi, Riad !!

I cannot see a reason why the bullet should land to the left or right. The friction forces will act in all directions alongside the circumference of the bullet. The aerodinamyc design allows penetration in the air and friction forces will tend to slow down the speed. Due to differences in pressure between the upper and lower areas, there will be a small force acting upwards, but vertical, and have no influence on the trajectory. Then comes into action the gravity acceleration with vertical direction. So, if there is no wind, there will not occur a change of trajectory outside the vertical plane.

Why is that you believe that the bullet will land to the left ??

Best regards

Alcir Grohmann


It is my opinion that the spiraling action caused by the riflings in the barrel will cause EQUAL amounts of friction from all points of contact with the barrel as it traverses the length of the barrel. So as the slug rotates down the length of the barrel there will be no preferential slowing to either side.

-Darin


The speed of the bullet (assuming perfect symmetry, smoothness, etc.) is so fast and the viscosity of air so small that the bullet's spin would have little effect on its trajectory. That is there is very little drag due to the air. What may be surprising is that the bullet you fired will hit the ground at the same instant as a bullet you dropped from your hand at the moment of firing -- again with all the simplifying assumptions.

Vince Calder



Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory