View Full Version : question about velocity
Impala
Sep 28th, 2006, 09:08 PM
Question
Let’s say a bullet fired from this rifle shots at speed X.
Now let’s say you are traveling on a train in one direction also traveling at X.
What would happen if you were to shot this rifle in the opposite direction of travel?
What would happen to the bullet?
Would it stop relative to the ground?
Hard to believe
Also is the train was traveling faster than X and the rifle was shot in the opposite direction would the bullet travel in the same direction as the train relative to the ground at the rate of the difference between X and the speed of the faster moving train?
again hard to believe
this question has been on y mind since I was like 12 never really got a solid annswer
nazarbayev1129
Sep 28th, 2006, 09:10 PM
http://www.redflagdeals.com/forums/showthread.php?t=346082
http://www.redflagdeals.com/forums/showthread.php?t=345924
What's with everyones fascination with physics...especially today :| BTW, I had a lesson on relative velocity today...is this some sort of sign?
Quan
Sep 28th, 2006, 09:17 PM
http://www.redflagdeals.com/forums/showthread.php?t=346082
http://www.redflagdeals.com/forums/showthread.php?t=345924
What's with everyones fascination with physics...especially today :| BTW, I had a lesson on relative velocity today...is this some sort of sign?
Sounds alot like my gr 11 homework, maybe people need help?
nazarbayev1129
Sep 28th, 2006, 09:21 PM
Sounds alot like my gr 11 homework, maybe people need help?
Yeah, motion was the hardest unit for me...but easy for my friends. Then the following units were easy for me, but hard for my friends.
:|
Impala
Sep 28th, 2006, 09:32 PM
http://www.redflagdeals.com/forums/showthread.php?t=346082
http://www.redflagdeals.com/forums/showthread.php?t=345924
What's with everyones fascination with physics...especially today :| BTW, I had a lesson on relative velocity today...is this some sort of sign?
Actually it was the thread about the plane and the treadmill that made me ask. BTW even I, with no background in physics, can tell the plane won't fly without lift from air traveling over the wings
m85d1
Sep 28th, 2006, 09:43 PM
It is hard to believe because the speed of bullet might be too fast for the train.
Things might a bit believable if you use the example of throwing a ball on a train instead.
Imagine you are standing on the ground, watching someone throwing a ball on a passing train. If the speed of the train and the speed of the ball are both x, but in different direction, then you should be able to see a ball that is motionless.
Impala
Sep 28th, 2006, 09:46 PM
that's why i am asking. that's the only conclusion i have been able come to But I feel as if i am missing something it's hard to believe
NiMSo
Sep 28th, 2006, 09:48 PM
The bullet should still travel at X speed relative to the ground, but at 2X speed in the opposite direction relative to the shooter on the train.
deep
Sep 28th, 2006, 10:03 PM
The bullet should still travel at X speed relative to the ground, but at 2X speed in the opposite direction relative to the shooter on the train.
A very nice, solid, authoritative answer. Also, completely wrong.
UrbanPoet
Sep 28th, 2006, 10:13 PM
yah.. but the guy will still come into contact with the bullet and DIE.
plus it simpossible.. the slowest crappiest moddern bullet i can think of would be a 45ACP going around 800fps....
unless ur talking about old school cartridges via black powder
NiMSo
Sep 28th, 2006, 10:16 PM
A very nice, solid, authoritative answer. Also, completely wrong.
Hey, ignorance is bliss :D. As long as something sounds sound (that was punintentional), you will believe it and be happy. Seems to work with politicians and lawyers. :lol:
deep
Sep 28th, 2006, 10:20 PM
yah.. but the guy will still come into contact with the bullet and DIE.
plus it simpossible.. the slowest crappiest moddern bullet i can think of would be a 45ACP going around 800fps....
unless ur talking about old school cartridges via black powder
You clearly missed the point of the Q...and besides, unless the target were also on the train, he wouldn't die.
If the target were standing beside the tracks and immediately after passing him, the shooter fired with the same velocity of the train (the magical maglev fusion powered super train, if you like) the bullet would just drop to the ground beside the target.
Get on a slow train and jump off with the exact same speed in the opposite direction, and you will nail the landing easily.
Rembrandt100
Sep 28th, 2006, 10:48 PM
You clearly missed the point of the Q...and besides, unless the target were also on the train, he wouldn't die.
If the target were standing beside the tracks and immediately after passing him, the shooter fired with the same velocity of the train (the magical maglev fusion powered super train, if you like) the bullet would just drop to the ground beside the target.
You are kidding right!
Once the gun has been fired it does not matter what direction or speed the train is travelling. As soon as the gun is fired the bullit will travel in the aimed direction at the velocity it was intended to move.
In the case above the target would be it instantly. Once the gun is fired any connection to the speed or direction of the train is severed. To accept your theory, it would also follow that if the train were moving in the opposite direction that the gun was aimed and at twice the speed of the bullit, then the bullit would not leave the gun when the trigger was pulled.
Dave
deep
Sep 28th, 2006, 10:54 PM
You are kidding right!
Once the gun has been fired it does not matter what direction or speed the train is travelling. As soon as the gun is fired the bullit will travel in the aimed direction at the velocity it was intended to move.
In the case above the target would be it instantly. Once the gun is fired any connection to the speed or direction of the train is severed. To accept your theory, it would also follow that if the train were moving in the opposite direction that the gun was aimed and at twice the speed of the bullit, then the bullit would not leave the gun when the trigger was pulled.
Dave
I have to quote this, so you won't delete it from embarassment after thinking it through. If you don't believe little old me, maybe:
http://science.howstuffworks.com/question456.htm
...will sort you out.
corrupt123
Sep 28th, 2006, 11:06 PM
ahahahah Deep's right. Rembrandt100 you just got owned.
Impala
Sep 28th, 2006, 11:25 PM
thanks for the link
guess that solves that one
Rembrandt100
Sep 28th, 2006, 11:31 PM
You did not really have to quote it little old you. I would not have deleted it anyway. I see no reason for you to be so consicending and a smarta$$. I did go to the link and read it. As far as I see it if the gun fires at 1000' fps, that is the speed the ammo will be at as it leaves the end of the barrel. If you would like to test it I am sure that I could find a straight streach of track if you can get the gun.
BTW you can play the part of the target.
Dave
deep
Sep 28th, 2006, 11:40 PM
You're the one who said "You are kidding right!"....and no, I was not kidding. When you correct someone, you should BE correct. When you're not, expect a jibe or two
We can simplify the experiment...you drive in a car away from me and throw a baseball at me, and then I'll drive towards you and return the favour. I doubt you'll like the way it turns out.