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1/25/2018 7:38:29 AM
Posted: 3/30/2002 2:30:18 PM EST
I was talking to a physics professor. We were talking about bullet drop. He stated that if in a perfect vaccum and the rifle was perfectly level and the ground is also level the following will occur. If a bullet was held at the same height as the barrel end and dropped at the instant the weapon was fired both would hit the ground at the same time. Granted the one fired would be way down range. The bullet that is fired has no aerodynamic lift such as a wing. Thus with the physics of gravity both will hit the ground at the same time. Interesting. Comments?
Link Posted: 3/30/2002 2:53:37 PM EST
I read the same thing in "Understanding Firearm Ballistics" by Robert A. Rinker. If I remember correctly, he stated that tests had been done in "real life" (no vacuum), and that the moving projectile actually hit ~.0005 seconds later that the one that was just dropped.

Sparked a whole evenings conversation at hunting camp last fall.

The book is a pretty interesting read, if you want to get into some of the "nitty gritty"...

Link Posted: 3/30/2002 2:57:30 PM EST
Your professor friend is correct. A whole subcatagory of physics is dedicated to the study of projectile motion....ballistics.
Link Posted: 3/30/2002 2:58:40 PM EST
I asked him about not being in a vacuum. He said even then the difference would be negligible. Based on what you read I guess he was right.
Link Posted: 3/30/2002 3:08:49 PM EST
[Last Edit: 3/30/2002 3:10:34 PM EST by kid223]
Your professor is right, All you have to do is apply the equation of a uniformly accelerated motion along the Y axis!

0 = Yo + V*sin(k)*T -G/2*T^2

where Yo is the height of the muzzle of the barrel of the gun from the ground, V is the velocity of the bullet at the muzzle, K is the angle that the barrel forms with the horizontal, T is the laps of time ( that's what you want to know ), and G is the constant acceleration of gravity.

If you isolate T in that equation you get: T = (( ((sin(k))^2*v^2 + 2G*Yo))^1/2 ) + sin(k)*V )/ G

Physics are fun !!! Kid223, Mechanical engineer to be.......two more years
Link Posted: 3/30/2002 3:13:31 PM EST
Got into thermal dynamics yet??? I love physics but damn thermal dynamics....smile.
Tom Civil Engineer
Link Posted: 3/30/2002 3:55:22 PM EST
Tom, my final thermodynamics exam is on april 11th !!!

It's not hard but there are a lot of different concepts to learn and you have to know where and when to apply them! Other than that is'not that hard !

Link Posted: 3/30/2002 4:01:44 PM EST
Not hard says you!!!! ha ha
Man it gave me fits.
You damn mechanical engineers....smile.
Thank god I don't use it in Civil!!! Roads, bridges and sewers...that's me!
Have a good one and keep in touch.
Link Posted: 3/30/2002 4:08:03 PM EST
Honestly I just stumbled into this topic by accident.

Now I'm going to stumble back out !
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