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Ahh the heady joys of Newtonian physicsOriginally posted by Robbo
Not so fast young man, the time for smiley faces isn't yet upon you, isn't the surface area directly proportional to its volume ?
If there is such a relationship, then the mass / volume ratio is still in contention as a determinant for accuracy is it not ?
Robbo
Inertia is the determinant of whether or not a projectile continues upon its path. Inertia is dependent upon mass
Wind resistance/Windshear is dependent upon surface area. The larger the volume/surface area the greater the force acting upon the object
Increase the volume of the sphere (and therefore the surface area) increase the force exerted upon it by the air.
Meanwhile, increase the mass and you therefore increase the inertia which must be overcome by that force. The greater the differential between the forces the less the flightpath will be altered
Where problem? (Please remember I was dealing with masses of equally sized projectiles to start with)
I'm sure you could give me the equations Robbo. But it's been a long time since I studied Physics (nearly 10 years since A-Levels)
Just as long as you don't shoot them at me I don't mind...Originally posted by Buddha 3
Oh, sod it! I'll just design some paintballs that weigh a kilo!
Great idea But I bet Iwould be the first to lose the Tweezers and toothpickOriginally posted by FAMINE
Swiss army paintball gun
Would include a ciggy lighter, bottle opener and thing for getting stones out of horses hooves
Originally posted by Hotpoint
Ahh the heady joys of Newtonian physics
Inertia is the determinant of whether or not a projectile continues upon its path. Inertia is dependent upon mass
Wind resistance/Windshear is dependent upon surface area. The larger the volume/surface area the greater the force acting upon the object
Increase the volume of the sphere (and therefore the surface area) increase the force exerted upon it by the air.
Meanwhile, increase the mass and you therefore increase the inertia which must be overcome by that force. The greater the differential between the forces the less the flightpath will be altered
Where problem? (Please remember I was dealing with masses of equally sized projectiles to start with)
I'm sure you could give me the equations Robbo. But it's been a long time since I studied Physics (nearly 10 years since A-Levels)
The point on inertia is agreed !
The inertia / mass relationship is also agreed !
Wind-shear volume / surface area point once again agreed !
In fact I ain't got any problem.....well, I have a little one....
My original suggestion, one that you refuted was that the ratio between mass and volume was significant when it comes to accuracy.
Now I want you to imagine something (much like the thought experiments employed by Einstein) imagine a beach ball being thrown, is it accurate ? Nope, and what of the ratio between volume (surface area) and weight?
The differential is large when compared to say a cannon ball of equal size where the ratio must be less but the cannon ball is inherently more accurate.
So it would seem the ratio between mass/ volume (surface area) does hold some practical significance when it comes to assessing relative accuracies.
Now am I playing devil’s advocate or do I have a point ?
Hee, hee, all will soon be revealed !!!
Robbo
Re: It's worse than that, it's physics Jim...
When you fire a paintball, even in a level plane it has accelleration, this for a short period, (where the ball flies horizontally), negates gravity. once the accelleration diminishes and we move into stable velocity and then negative accelleration, (proper term for decelleration) then gravity has a greater affect and pulls the ball back to earth.
If that didn't work we'd never have orbiting satellites as IIRC the velocity acts against gravity and the curvature of the planet and puts the object into constant free fall.
Theoretically if we could fire a paintball at a high enough velocity with minimal drag it would orbit the planet until it hit something.
If a paintball fired from a marker hit the floor at the same time as one you dropped there'd be no point in playing as the ball wouldn't go very far.
Or at least that's how I remember it.
er, it's been a long time since I did my A level physics, but I'm almost sure this is incorrect.
When you fire a paintball, even in a level plane it has accelleration, this for a short period, (where the ball flies horizontally), negates gravity. once the accelleration diminishes and we move into stable velocity and then negative accelleration, (proper term for decelleration) then gravity has a greater affect and pulls the ball back to earth.
If that didn't work we'd never have orbiting satellites as IIRC the velocity acts against gravity and the curvature of the planet and puts the object into constant free fall.
Theoretically if we could fire a paintball at a high enough velocity with minimal drag it would orbit the planet until it hit something.
If a paintball fired from a marker hit the floor at the same time as one you dropped there'd be no point in playing as the ball wouldn't go very far.
Or at least that's how I remember it.
Not convinced by the inertia argument, that one I really am struggling to remember, (something to do with resistance to changes in motion rather than continuation of momentum), so if the next bit is immediately proved wrong by a physisict out there so be it, I'm originally a Chemist by trade.
the mass to volume ratio you are referring to Robbo makes perfect sense if you are referring to mass divided by volume which is the density of the object rather than simply concentrating on surface area which is governed by the square-cube ratio, (more later).
A beach ball of exactly the same size as a cannon ball has a lower mass when compared to it's volume and is therefore easier to affect in terms of wind etc, as I recall this is due to it being able to be accellerated to a velocity V with less force because it suffers from less inertia, (less mass/volume or density), the problem with this would be that it's lower mass for the surface area results in less density and hence less resistance, (inertia again) to decelleration and/or directional movement and thus diminished range/accuracy. It also will have other problems such as distortion of surface shape under accelleration etc occuring making it inherently less accurate.
A cannon ball generally being a solid object has a larger mass for it's surface area and therefore has a greater inertial resistance to accelleration, putting it simply it takes more effort to fire it, (try throwing a cannon ball vs a beach ball of the same size). The advantage of a more dense round is that once it is moving its greater inertia means that it is less affected by negative accelleration and directional movement meaning that it takes more effort to get it there, but at least it will get there. The range of the shot is governed by the density of the object and the force used to propell it. If the mass M is constant between rounds they should, all other things being equal arrive at the same point at exactly the same time. Gravity overcomes inertia at roughly the same point if M and V are the same for each round, at which point the ball will begin a downward trajectory as well as a horizontal one.
I think this means that in terms of paintballs there has to be a balance between the density of the ball for a fixed volume sphere and the force needed to accellerate them.
Too much mass and the inertial force becomes higher and it requires more force to propell the round at the same velocity, the shell has to be thicker to cope with the higher energy at firing but the round should be less affected other forces during flight.
Lighter round, less energy require to overcome inertial force which means it can have a thinner shell, but it is more affected by other forces during flight.
So you have to trade off a degree of accuracy for the ability to break the ball on the target if the impact is at an equivalent velocity/force.
I think the surface area to volume ratio is governed by the square-cube ratio.
What this means is that as the surface area of an object increases by the square (E+2), the volume of the object increases by the cube, (E+3).
This is a quote from a book I was reading the other day that illustrates the problem here
If you doubled the diameter of the planet and the height of a man on it's surface, his mass would multiply by a factor of eight and the planet by a similar amount so his weight would be sixty four times as much as before. The problem with this is that the cross section of his legs would be only four times as much which means that the burden on his feet would be about sixteen times the prior burden - without strengthening his flesh. It's why ants cannot grow to the size of elephants without changing form radically
though it's just something I read and I'm assuming it's accurate but take no responsibility if it's not. Me just a thick ex-chemist management trainery type bod
and how you could apply this to a paintball I'm not sure as it's now far too late and I've worn out my brain cell.Good discussion though
Re: Re: It's worse than that, it's physics Jim...
(with absolutely no help at all from my girlfriend, who's just finished her final year physics degree )
The ball that is dropped has acceleration in the vertical (towards the ground), but a "zero" acceleration in the horizontal plane.
The ball which is "fired" has acceleration in the horizontal plane (both positive and negative), but it also has acceleration in the vertical plane.
Initially, the acceleration and velocity in the vertical plane are slow, leading to the impression that there is no movement in that direction (ie, the ball is only travelling horizontaly).
If both balls are released from the same height, at the same time, and the ball which is fired is fired perfectly horizontaly, (ignoring any possible aerodynamic effects which may or may not cause lift on the fired ball), both balls will reach the ground at the same time.
The above paragraph does not work if you are shooting at the side of a hill.
Wow, an intelligent converstaion I can take part in
(with absolutely no help at all from my girlfriend, who's just finished her final year physics degree
)The ball that is dropped has acceleration in the vertical (towards the ground), but a "zero" acceleration in the horizontal plane.
The ball which is "fired" has acceleration in the horizontal plane (both positive and negative), but it also has acceleration in the vertical plane.
Initially, the acceleration and velocity in the vertical plane are slow, leading to the impression that there is no movement in that direction (ie, the ball is only travelling horizontaly).
If both balls are released from the same height, at the same time, and the ball which is fired is fired perfectly horizontaly, (ignoring any possible aerodynamic effects which may or may not cause lift on the fired ball), both balls will reach the ground at the same time.
The above paragraph does not work if you are shooting at the side of a hill.
Re: Re: It's worse than that, it's physics Jim...
The acceleration factor is academic as long as that acceleration is once again, starting in a horizontal direction.
Sorry mate, I like your style and all that but you need to resit your A level Physics
Laterz
Robbo
Hey Cube, as long as the ball is fired in a horizontal direction, the time taken to hit the ground is (and must be) exactly the same as a ball being dropped from the same height !!!!!
The acceleration factor is academic as long as that acceleration is once again, starting in a horizontal direction.
Sorry mate, I like your style and all that but you need to resit your A level Physics
Laterz
Robbo
Hey Cube, I think you have just made the point, in a roundabout way that I was originally suggesting....it just remains for Hotpoint to rebut or to enlighten.
I await Hotpoint's reply with baited breath
Robbo
I await Hotpoint's reply with baited breath
Robbo