Index  •  FAQ  •  Search  

It is currently Thu Mar 28, 2024 11:18 am

This is a static archive the Twin Cities Carry forum, maintained as a public service by the current forum of record, The Minnesota Carry Forum.

All times are UTC - 6 hours




Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 4 posts ] 
 Sectional Density 
Author Message
 Post subject: Sectional Density
PostPosted: Sat Jul 12, 2008 8:24 am 
Longtime Regular
User avatar

Joined: Thu Aug 31, 2006 12:17 pm
Posts: 908
Location: Meeker Co., MN
Why does the shooting industry/sport calculate sectional density different than classical physics?

Whereas the SD of a given object is generally calculated by dividing the mass of the object by the cross section area. Determined by the orientation of the view.

In bullets I often see it determined by dividing the weight of the bullet in pounds by the diameter^2 in inches.

The weight vs mass conflict I can accept. (Grudgingly) Since most bullets will be used on or near the surface of the Earth. But, why change from the cross sectional area (pi*r^2) to D^2.

TIA

_________________
1 of 55153
"The attitude of people associating guns with nothing but crime, that is what has to be changed. I grew up at a time when people were not afraid of people with firearms." —Supreme Court Justice Antonin Scalia
Sierra Trading - Firearms Sales, Service and Training


Offline
 Profile E-mail  
 
 Post subject:
PostPosted: Sat Jul 12, 2008 8:46 am 
Longtime Regular
User avatar

Joined: Thu Aug 31, 2006 12:17 pm
Posts: 908
Location: Meeker Co., MN
Follow-up note: A Wiki article will invariably come up while doing a search. This one is most curious. It uses a conventional physics formula in its body, but cites a Chuck Hawks article as it's source. Yet, Chuck Hawks uses the bullet type formula, unlike the formula in the text. :?:

I think the bullet formula was invented as a convenient way to compare calibers and masses of bullets. It really has nothing to do with the actual sectional density.

_________________
1 of 55153
"The attitude of people associating guns with nothing but crime, that is what has to be changed. I grew up at a time when people were not afraid of people with firearms." —Supreme Court Justice Antonin Scalia
Sierra Trading - Firearms Sales, Service and Training


Offline
 Profile E-mail  
 
 Post subject:
PostPosted: Sat Jul 12, 2008 4:11 pm 
Longtime Regular
User avatar

Joined: Sat Jun 10, 2006 9:53 am
Posts: 1263
Location: MN
I saw the title of this thread and perked up. "Hey!" I thought, "I'm not the only one in the group who knows about sectional density."

...Until Kona started reeling off formulas. Then it sort of changed to, "Erm. I thought I knew about sectional density, but really I just know that 1) it's generally good and 2) how to get more in a few circumstances." :lol:

Sorry, Kona. Can't help you there. Math makes my eyeballs spin and shuts down my brain.

_________________
Image
Image courtesy of Right Wing Swag


Offline
 Profile  
 
 Post subject:
PostPosted: Sat Jul 12, 2008 4:53 pm 
Longtime Regular
User avatar

Joined: Thu Aug 31, 2006 12:17 pm
Posts: 908
Location: Meeker Co., MN
:D That's okay!! It keeps me in a job teaching others. :D

_________________
1 of 55153
"The attitude of people associating guns with nothing but crime, that is what has to be changed. I grew up at a time when people were not afraid of people with firearms." —Supreme Court Justice Antonin Scalia
Sierra Trading - Firearms Sales, Service and Training


Offline
 Profile E-mail  
 
Display posts from previous:  Sort by  
Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 4 posts ] 

This is a static archive the Twin Cities Carry forum, maintained as a public service by the current forum of record, The Minnesota Carry Forum.

All times are UTC - 6 hours


 Who is online 

Users browsing this forum: No registered users and 18 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron


 
Index  |  FAQ  |  Search

phpBB © 2000, 2002, 2005, 2007 phpBB Group