# Question why: slingshot only 300 fps yet BB rifle 785 fps

• posted
Some pellet airguns boast of breaking the sound speed with 1,200 fps.
Now I have a question that only a real scientific mind can answer and
not
these jimmycrackloudmouths on the Internet. The question I am going
to ask is that the question is probably more profound than what the
is. So please do not dive into this question.
Question: I notice that my BB airguns have but a small cylinder that
holds
the pumped compressed air. Just a small cylinder that shoots a BB at
close to 800 fps. The maximum a slingshot can do is 300 fps. So I look
at
these two reservoirs of energy of a small cylinder with compressed air
and a slingshot of its large elastic. And I wonder, why is compressed
air
in such a small cylinder have so much more force than this large
elastic.
So the question is Elastic X factor = Air. What is the physical
underpinning
as to why elastic always falls short of compressed air?
Can we equate compressed air to EM elastic and is the answer have
something to do with the fact that EM elastic has cancelling energy
whereas the compressed air has little to none cancelling energy
and can focus the energy on the BB.
Archimedes Plutonium, a snipped-for-privacy@hotmail.com
whole entire Universe is just one big atom where dots
of the electron-dot-cloud are galaxies
• posted
it's a conspiracy fronted by the black helicopter people. they dont want joe citizen to realize how awsome a weapon a slingshot may be.... their mind control waves make their victoms view a slingshot's projectile apear to travel in 'bullet time', ie having the apearance of very slow motion. if you don a tin foil hat you will block out the mind rays and see the true potential of your average of this devistating weapon. your average slingshot is capible of accelerating a projectile to superluminal speeds causing great devistation to it's target..
• posted
If that is the case, the slingshot could be improved by having a two-stage action, in which a slow, heavy primary projectile strikes a target that holds a small, light (but dense) secondary projectile. That secondary projectile would then come whizzing out at supersonic speed. (There may be more stages of energy transfer needed here to get good overall efficiency.)
• posted
There's a limit to how fast an elastic band can revert to its original size. Nothing, no matter how light, can travel faster than this limiting speed. Likewise, there's a limit to how fast air molecules travel also, but I think its a few orders of magnitude faster than the elastic band's limit.
• posted
You could do better if you replaced the rubber with steel and were able to use the elastic properties of steel. I expect you would reinvent the cross bow. But an even simpler weapon than the improperly named sling shot the simple sling delivers much more energy buy using larger ammo and comparable or higher speeds. A sling shot is very unlikely to kill a man a sling and the proper stone will do so quite efficiently.
Gordon
• posted
Isn't the energy delivered by both almost equal? That is a heavy item at slow speed can have as much energy as a small item at high speed. After all Ft=mv. If Ft ( or impulse ) is constant then as mass goes up, velocity can decrease for the same impulse. A big, slow slug is good for stopping power, whereas a small fast slug is good for penetration.
Al
• posted
Never heard of that before. If it does what I think it does, its clever, but it doesn't change what I said above.
• posted
Thats true with respect to the slingshot (or ground in the case of the cannon), but not with respect to the last object hit. Its a great way to get around the limitation, but the limit applies to the interaction of the two objects (two balls/band and shot), not to a more complex system, as-a-whole.
BTW, I don't see how having a 3rd object in the slingshot would help. The Minski cannon is the result of several elastic collisions where each ball ends up bouncing UP against the ball above it, adding to the collision-speed of the higher ball. I don't see how that interaction would happen with the slingshot. You could get max momentum from the large object interacting with the band, and than pass the energy to the lighter object, but I don't see where you gain anything from having a third since there's no extra kinetic energy involved in their interaction, just a difference in mass.
• posted
Not quit, Al. F =mvv or velocity squared. The faster smaller projectile has more energy. When comes to damage the energy dissipated in the victim that counts. A high velocity bullet that shoots a clean hole and miss anything vital doesn't do much damage But a slower less emetic one that expends all it energy bouncing around inside the body can do a lot more damage.
Gordon
• posted
You're both wrong. Consider two bullets of equal energy. One is small and fast, and the other is large and slower.
Energy is (mv^2)/2, so a little increase in velocity increases energy a whole bunch. Momentum is mv, so increasing velocity only increases momentum linearly.
The small, fast bullet has lots of energy, but not much momentum, so it dumps its energy very easily when it hits something. The large, slower bullet with the same amount of energy has lots of momentum, so it goes right through whatever it hits, without dumping much energy.
That's why a high-velocity rifle bullet can just touch a deer or something, and it's like an explosion.
• posted
I think you meant to say that the fast bullet goes right through and the large momentum slower bullet dumps its momentum onto the target and bowls it over.
further confusion.. for it is more like an acupuncture and explosion has nothing to do with it.
What I am interested in is why the sound barrier is easily exceeded by energy reservoirs of IdealGasLaws such as BB rifles but EM reservoirs such as slingshot or archery seem never able to reach the sound barrier.
But from reading your above I sense that IdealGasLaws favor velocity in 1/2.mv^2 whereas Maxwell theory of EM has only a linear increase in momentum.
So the bifurcation of energy reservoirs is split into whether it favors energy or momentum. The IdealGasLaws favor energy, and Maxwell theory favors momentum.
So we end up with a favoring whose difference is that of v^2 to just simply v. Mark, question, since 1997, I pegged the Fusion Barrier at 2/3 breakeven. Question, can we get 2/3 number out of a difference of v^2 to that of v??????
I think the difference between v^2 and v (or energy versus momentum) is a dimensional difference because exponents have a tendency of shifting physical reality from say 1 dimension into 2nd dimension.
Fission obeys the IdealGasLaws and fission exceeds breakeven with its chainreaction neutrons. So is fission the v^2 energy reservoir but that Fusion is forever stuck with momentum and linear v and never v^2????
Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
• posted
If you assume a spheres - a small sphere has more momentum/ (unit cross sectional area) than a large sphere - more penetrating power a large sphere has more total momentum - more knock down power. I know from my youth that woodchucks explode when hit with a small caliber high velocity round because the bullet is designed to tumble once it hits flesh. This efficiently transfers the KE of the projectile to the target.
• posted
If they both have the same mass, then duh -- the large, low-density bullet has more efficiency transferring its energy to the target than the small, high-density bullet.
But that's not what I was talking about. I was talking about low-mass, fast bullets vs. high-mass slow bullets. If two such bullets have EQUAL energy, the low-mass bullet has much LESS momentum than the high-mass bullet. When the low-momentum bullet hits the target, it transfers its energy very efficiently. When the high-mass bullet hits the target, it would tend not to transfer its energy very efficiently -- it would tend to plow right through the target.
Your observation with regard to exploding woodchucks is correct, but your theory is faulty. Tumbling certainly helps transfer energy, but the woodchucks would explode even if the bullets did not tumble at all. It's all due to the low momentum and high energy of high-velocity rifle bullets.
• posted
Mark, how is commonsense and common observation wrong. When a fast small BB hits a rabbit it goes straight throw and leaves a perforation and holes at both ends. That is because as you say, the v^2 in energy whereas the slingshot of a pebble with its large mass and slower speed is mostly momentum. So when the pebble hits the rabbit it dumps its energy. When the small fast speed BB hits the rabbit, it does not explode nor does it dump its energy but rather goes right through since it is so fast and small mass.
I hunt almost daily because the rabbit population this year exploded, but I doubt that you ever get a chance to hunt Mark from the descriptions you are making.
Perhaps my choice of terms of acupuncture were a poor choice. Instead I should have chosen "perforation" or "penetration". Because a very fast small mass will just go sailing through the medium it hits such as a supersonic BB hitting a rabbit but then a pebble from a slingshot at 300 fps will not penetrate or perforate the rabbit but its momentum may stun and daze the rabbit.
Your physics is all correct Mark, but your translation back into the real world experiences are wrong.
Archimedes Plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
• posted
Do a calculation of momentum/ (unit cross sectional area) using speheres of the same density and same energy but differnt diameter. this should be indicative of transfer effieciency.
After the America took control of the Philippines, The US issued small caliber high velocity side arms to US troops - the problem was that the small caliber ammo passed right through the adversary with out stopping them - The US military then adopted the .45 which could stop an attacker with one shot. The US went back to small caliber ammo when it learned how to make the bullet deflect when it hit flesh - with the M-16 you can shoot a man in the leg and the bullet may come out the arm.
At close range a .223 rifle will tend to go right through a wood chuck - at 100 yrds the animal explodes
• posted
Obviously - a non-tumbling bullet even with more energy just passes through - that was was point I didn't express clearly
Yes - the soft jacket deforms and helps transfer energy to the target - it stays intact and can glance around depending on what it hits
If the bullet passes through the target - it didn't transfer the all of it's energy to the target - the original point of the post A larger cross section will help transfer the energy to a soft target.
The object for many military small arms is to wound not kill - it takes two men an hour to bury a corpse and a lot of care and resources to nurse a badly wounded soilder.
• posted
huh? where on Earth did you come up with that completely false supposition?
you have made yet another idiotic statement?
yes and 1/3 of my money goes to the government.... ooo... another conspiracy.
Raz

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