Velocity is a vector quantity.


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zahc
September 28, 2004, 12:12 AM
Does it bother anyone else that projectile speed in the gun world is called velocity even though the only thing of interest is the speed?

Who's gonna start calling it 'muzzle speed' or 'high speed .22s' instead of high velocity?

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Mal H
September 28, 2004, 12:18 AM
"Does it bother anyone ...?"

Not me. :)

Bullets generally go in one direction only, so we might as well call that a positive direction (vector).

JohnBT
September 28, 2004, 07:29 AM
The first definition in this dictionary says: 1. Rapidity or speed.

The second one says: 2. Physics. A vector...

John...I was a physics major once upon a time

mete
September 28, 2004, 09:49 AM
When the bullet richochets off the rock and hits you the velocity[since it returned to it's original point] is zero but it does have speed .

trapperjohn
September 28, 2004, 10:04 AM
i teach mechanical engineering, and have taught physics so I know what vectors are.

Does it bother me? Not at all, not worth getting upset about in the least.

GD
September 28, 2004, 12:01 PM
I figure mine to be velocities. Outgoing is positive, incoming is negative!:rolleyes:

S Roper
September 28, 2004, 12:17 PM
Mass and force confusion bothers me a lot more.

mondocomputerman
September 28, 2004, 12:55 PM
The components of velocity are speed and direction. And yes I have thought of it before. And no, it doesn't bother me, unless the direction is towards me!

45crittergitter
September 28, 2004, 01:40 PM
When the bullet richochets off the rock and hits you the velocity[since it returned to it's original point] is zero but it does have speed .

Wrong. If it is still moving, it has speed and direction; therefore it has velocity.

The first definition in this dictionary says: 1. Rapidity or speed.

Also wrong. Dictionaries are notorious for getting technical definitions wrong. Basically anything moving has velocity, since velocity is a vector whose value or magnitude is speed and whose other component is direction.

JohnBT
September 28, 2004, 02:16 PM
But it's not a technical dictionary, it's an English dictionary. :neener:

John

boing
September 28, 2004, 05:46 PM
You know, we're still fighting an uphill battle with clips and magazines, and bullets and cartridges. One step at a time, okay, guys? ;)

Bwana John
September 28, 2004, 09:37 PM
Yes, you are correct. It turns out that velocities have more that just a size. They also have a direction. For example, a statement correctly stateing a velocity would say, "The velocity equals 25 meters per second North ." Notice that two things are necessary to state a velocity, as magnatude, that is, 25 meters per second, and a direction, North. This is how you talk about velocities when you are studying physics. The size of the velocity is called the speed. So, we would say that velocity is made up of a speed and a direction. Quantities like this, that have magnatudes and directions, are called vectors.

Red Tornado
September 28, 2004, 09:48 PM
While we're picking nits, how about 'bullet speed', since the muzzle's not really moving that fast? :evil:
RT

Can'thavenuthingood
September 28, 2004, 10:14 PM
Kick this around long enough and there'll be a discussional malfunction.

Velocity indicates the speed of a projectile in flight.

Velocity is measured in feet per second

A direction isn't needed for velocity other than to measure between 2 points.

Or the direction is indicated as the projectile is moving away from point of origin.

Roger, vector Victor

Vick

trapperjohn
September 28, 2004, 10:57 PM
Velocity indicates the speed of a projectile in flight.
.A direction isn't needed for velocity other than to measure between 2 points.

technicaly that is incorrect

speed= distance traveled divided by the time it takes to travel it

velocity= speed AND direction

speed is a scalar value, it has only magnitude NOT direction

Velocity is a vector value, it has magnitude AND direction


that being said, that is the definition used by scientist and engineers to differentiate the two.

for the average person velocity and speed are the same in their minds

Andrew Rothman
September 29, 2004, 12:15 AM
In ENGLISH, velocity=speed.

The question is, are we speaking English or Physicist when we talk about ballistics?

And, jeez, this is a lame quibble. Can't even believe I'm writing this!

M1911Owner
September 29, 2004, 01:23 AM
Mass and force confusion bothers me a lot more. Yah, especially when the confusion ends up giving you specific impulse in seconds. :barf:

More seriously, to those of us who've spent years working with vector quantities, it's self-evident that speed and velocity are completely different animals. But, that's just because physics has made a specific definition for a word that has a different meaning in the rest of the English language. To everyone else out there, "velecity" is a synonym for "speed."

This is rather like certain groups who have decided that they don't like having the word "he" be a generic that can mean "he or she," and get all bent out of shape when people say "he" instead of "he or she."

Obiwan
September 29, 2004, 08:10 AM
What always got me was that;

Because velocity is a vector quantity

And because accelleration is a "change in velocity"

That ricochet was (by definition) a form of acceleration...even if the spped remained constant.

zahc
September 29, 2004, 08:16 AM
Not only that, but the change it bullet speed as the bullet travels downrange is an acceleration, even though the bullet is slowing down.

WEPS
September 29, 2004, 08:41 AM
velocity and speed are two diferent things. if a car was driving in a big cricle it's speed might stay the same but it's velocity would be changing. i don't remember the technical terms for it but velocity is the rate of travel in one given direction.

RJ357
September 29, 2004, 10:27 PM
You might as well include the gravitational field too, as an acceleration. Einstein showed them to be equivalent (general relativity).

Deavis
September 29, 2004, 11:02 PM
if a car was driving in a big cricle ... i don't remember the technical terms for it but velocity is the rate of travel in one given direction

Are you trying to lead us into a discussion of centripetal motion? Constant acceleration in a direction other than the velocity? Not on my watch! :neener:

Vectors and scalars and derivatives, oh my!

hso
September 30, 2004, 12:11 AM
If you expressed your turning car's motion in polar coordinates then your velocity would be constant (jeeeeeeeeez, I'm a physics NERD )

chevrofreak
September 30, 2004, 11:04 AM
my head just exploded

Nippy
September 30, 2004, 03:31 PM
This post just went south after trapperjohn lmao

Reno
September 30, 2004, 03:49 PM
I would have a real problem if the velocity was in any direction other than co-axial to the barrel.

iapetus
October 1, 2004, 10:47 AM
zahc
Senior Member

Registered: Mar 2003
Location: Salesville, OH
Posts: 1065
Not only that, but the change it bullet speed as the bullet travels downrange is an acceleration, even though the bullet is slowing down.


You could reasonably call it "negative acceleration" (assuming downrange was the positive direction).

But then you'd sound like a manager...

Black Snowman
October 1, 2004, 12:08 PM
I used to get my panties in a bunch over symantics but I'm getting to old and lazy to be elitest anymore ;)

Nippy
October 1, 2004, 12:27 PM
Old habits die hard;)

WEPS
October 1, 2004, 08:38 PM
Deavis
is that suppose to be Beavis cause you sure sound like one.you know what the problem is with some of you guys? you look for the most ridiculous things to blast someone on. everybody wants to be the expert an everybody wants to through stones instead of kindly expressing there views. most of what is said here on the highroad is sound for the most part. but some people will sit there and assume, disect, twist around and missunderstand what is said just so they can argue. you people know who you are and it makes me sick. i know what i was trying to say about velocity and i know i am right. i just don't have the a vast enough vocabulary to express it , and im not going to search the web for hours just so i can look smart and prove some poor bastard wrong.

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