# The Naked Scientists Forum

### Author Topic: How does a Gauss Rifle work?  (Read 9281 times)

#### johnson039

• Jr. Member
• Posts: 28
##### How does a Gauss Rifle work?
« on: 26/12/2008 14:44:03 »
as you all know, with a set of identical metal balls, lining them up, when i use one to strike them, by the conservation of momentum, the last one in the queue will move on with the same velocity as the first ball(that was pushed by me) (assume friction is neglegible and the experiment is done in vacuum.)
O -----> OOOOOO                 OOOOOO -----> O

so now, my question is,
if I put a magnet on the second ball like that:
O -----> "OOOOOO                 (" = magnet)
i use the same force to push the first ball, wif the same initial velocity, but when it approaches the set, the magnet will attract the ball and the ball will be accelerated instantaneously. So the 'cannon' shot out will have much larger momentum than the one before.
O"OOOOO ----------------> O

i want to ask that, the 'cannon' shot out in this situation, if compared to a metal ball only repelled by a strong magnet, will it have a higher momentum and kinetic energy?
« Last Edit: 01/01/2009 04:06:23 by chris »

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Re: How does a Gauss Rifle work?
« Reply #1 on: 27/12/2008 23:53:26 »
This question is not worded in a way that allows it to be answered as it contains several non sequeteurs and some imoportant details missing.  Johnson please rewrite it to make it very clear prcisely what you would like to know.

#### lightarrow

• Neilep Level Member
• Posts: 4586
• Thanked: 7 times
##### Re: How does a Gauss Rifle work?
« Reply #2 on: 28/12/2008 12:49:37 »
as you all know, with a set of identical metal balls, lining them up, when i use one to strike them, by the conservation of momentum, the last one in the queue will move on with the same velocity as the first ball(that was pushed by me) (assume friction is neglegible and the experiment is done in vacuum.)
O -----> OOOOOO                 OOOOOO -----> O

so now, my question is,
if I put a magnet on the second ball like that:
O -----> "OOOOOO                 (" = magnet)
i use the same force to push the first ball, wif the same initial velocity, but when it approaches the set, the magnet will attract the ball and the ball will be accelerated instantaneously. So the 'cannon' shot out will have much larger momentum than the one before.
O"OOOOO ----------------> O

i want to ask that, the 'cannon' shot out in this situation, if compared to a metal ball only repelled by a strong magnet, will it have a higher momentum and kinetic energy?
Of course the ball of your cannon will be faster than that repelled by a magnet and starting from no speed: your bullet doesn't start from no speed: it has an initial non zero speed, so this initial speed will be summed to the one get only from the magnet repulsion.

Note that the magnet should have the same mass (and, possibly, made of the same material) of all the other balls, to transfer momentum in the way you intend.

Since you talked about it, now make a "mental leap" and think instead to this situation: what happens if (magnet or not magnet) the first ball has 2 times the mass of the second, which has 2 times the mass of the third...and so on to the last, let's say to the 10th? If the ball n.1 has a speed v, which is the speed of the ball n.10?
If you find the solution you find an interesting thing...
(In case you want to patent this last gun system, remember that I was the one who gave you the idea  ).
« Last Edit: 28/12/2008 13:01:18 by lightarrow »

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Re: How does a Gauss Rifle work?
« Reply #3 on: 28/12/2008 22:52:23 »
Light arrow I agree that explains things in the first three paragraphs but not the main question.

Quote "i want to ask that, the 'cannon' shot out in this situation, if compared to a metal ball only repelled by a strong magnet, will it have a higher momentum and kinetic energy?"

There are also other potential problems because if one of the bals was magnetised and they were all of the same sort of material and therefore ferromagnetic the balls would be stuck together with induced magnetic fields.

PS interesting suggestion about the set of decreasing sized balls and impusive forces.

#### johnson039

• Jr. Member
• Posts: 28
##### Re: How does a Gauss Rifle work?
« Reply #4 on: 31/12/2008 01:48:01 »
ha, light arrow, i m not trying to get the patent of this system, it's just a little experiment carried by me and a few fds of mine at school as a science demonstration.

that's an interesting suggestion about the halving size of balls

#### lightarrow

• Neilep Level Member
• Posts: 4586
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##### Re: How does a Gauss Rifle work?
« Reply #5 on: 31/12/2008 12:15:13 »
ha, light arrow, i m not trying to get the patent of this system, it's just a little experiment carried by me and a few fds of mine at school as a science demonstration.

that's an interesting suggestion about the halving size of balls