Actually, that was some pretty deep powder on a 45 degree slope with no major oncoming obstacles. If you're going to hit something at Mach 6 and survive, it would be powder snow.

Several videos out there of people skydiving and surviving hitting the ground at terminal velocity with only a drag chute deployed. Granted, they are major puckered units, but that is a situation more akin to "almost died".

I guess what I mean is, I don't classify near misses as "almost dying". It's like saying she's "almost pregnant" after pulling away before coitus.

I had always thought speed = velocity, but I was thinking of instantaneous, not average.
http://www.physicsclassroom.com/class/1dkin/u1l1d.cfm

....got so booglerized from reading the back 'n forth between newt 'n trance that I slipped into a newttransmittance er summpthin'...I now side with your particular take on your own delusional ramblings Velocity, carry-on please

Actually I'm about as English as they come but crucially I spent my advanced academic career studying Philosophy and rhetoric (lamentably only to Hons. due to laziness) and consequently have an ingrained habit of arguing around a problem rather than relying on established parameters (not always entirely helpful when discussing more day to day matters as I'm sure you've by now gathered but it is essential to working with advanced epistemological problems and so serves me well none the less). I'm also prone to poor punctuation and odd patterns of grammar when I'm not going back over everything I write with a fine tooth comb which has likely not helped. (A consequence of learning to describe tangent after tangent when trying to thoroughly encapsulate some conceptual problems with language alone)

That said, while I may have gone around the houses so to speak I think my conclusion is entirely compatible with what I now understand your own to be.

I didn't want to describe my original counter-point by simply working with the idea that weight is lower on the moon relative to the earth (though I did not try to refute this either) because that would not illustrate why a 2-300kg man in a space suit still takes some shifting (relatively speaking) even if there were no gravity at all. (Would have been faster to just crunch some numbers but that's not what I specialise in)

Sure you could move anything with any force in 0G (which I do understand is technically relative as every object in the universe with mass exerts gravitational forces proportionately (and inversely proportional to the distance between)) but the resulting velocity is directly proportional to mass vs force applied. Weight here then, can be seen as another competing force in the equation rather than the whole thing which it can be convenient to treat it as for a simple calculation (which is what I think you are doing).

To put that another way I was applying a different/deeper linguistic/descriptive paradigm to the same objective facts because that's what we philosophers do. Single paradigm approaches to any subject have a dangerous habit of making one believe one possess such a thing as truly objective facts rather than interpretations only (which are all that truly exist).


In other terms weight alone isn't the whole story (as I assume you well know). Overcoming inertia due to mass scales up all by itself, then gravity comes along and complicates matters. This is why rocket scientists measure potential thrust in DeltaV rather than Watts, Joules etc. right? The mass of the object dictates how much velocity a given input/output of energy would equal.

Gravity and thus the force in newtons it induces (weight) in these terms is an additional force which depending upon the direction in which it is acting multiplies the required DeltaV to achieve the same effect. Moreover when concerning a force of inconstant nature (such as pushing up/jumping or a brief burn of an engine) brings duration into play also. (the foundations of why rocket science gets its fearsome reputation for complexity in its calculations)


Man on the moon lies on the ground and pushes off to try and stand back up.
This push must impart enough DeltaV to his body to produce a sufficient velocity and duration to travel the 2 meters or so needed to get upright so he can then balance the downward gravitational force with his legs&back and successfully convert the chemical/kinetic energy from his arms into potential energy as weight (the energy he uses to stand up is the same energy that would drag him down again right?).

One could practically speaking reduce this to a simple calculation of weight and thrust if all one wanted was a number. Weight would be the only number we need here as it incorporates the mass in it's own calculation (weight = mass x gravity)

But where's the fun in that? My way let's one go round all the houses see how the other bits of the paradigm that support this basic isolated equation function and inter-relate.

Plus (and probably more accurately) I've been playing loads of Kerbal Space Programme lately and have ended up conditioning myself to think in terms of rocketry and thus massively overcomplicated everything here for basically my own amusement/fascination.


Basically few things are more verbose and self indulgent than a bored Philosopher, sorry .


Re: Your challenge. (And I'm just guessing here) something to do with your leg muscles not being able to deliver the energy fast/efficiently enough? (as your feet would leave the ground faster/at a lower level of force?). This is the only thing I can think of as it's easier to push away from things underwater and it certainly looks difficult to push away hard from things when people are floating in 0g.

So lower resistance from gravity = less force to push against the floor with?

Warm? Even in the Ballpark? (Regardless I'm really pleased to discover you weren't the nut I originally thought you to be! (though I imagine you now have some idea what a nut I am))


If I got any of that wrong I'd be happy for you to explain to me why and where (assuming you can keep up with my slightly mad approach to syntax in the 1st place). I'm an armchair physicist (not that I haven't studied it in my time but I'm far from PHD) I'm always happy to learn and improve.

That's not what I was saying at all though perhaps I explained poorly.

So imagine you are in a 0 gravity environment. You have 2 balls (lol) one has a mass of 1 kg the other a mass of 100kg. You throw both equally hard. What happens?

One ball travels away from you at 100x less the velocity of the other. This is intertia, it is an effect of mass not gravity. Gravity is an additional force but it's absence would not change the fact that a big heavy space suit requires a significant force to move at a usefully velocity in the 1st place.

It was perhaps misleading to use the example of a fulcrum (lever) but in this context it's quite illustrative. If it was 0 gravity you could apply a tiny force to a massive object and just wait however long it takes to get it where you want (like an infinitely long lever). When gravity becomes a factor duration becomes more and more of a concern (like the fulcrum of the lever gets shorter and shorter).

Concequence: the lower the gravity the easier (less work/deltaV) it is to move an object. However a massive object still requires a proportional large force to move in a useful way (in this case fast enough to overcome 0.16g for long enough to get upright).

I'm not saying gravity has no effect (quite the opposite) I'm saying big heavy thing requires big heavy force to shift even in reduced gravity environments.


As for bases on the moon, mars, stargates, ueo's, void whales, phobos being hollow (phobos is some crazy shit), hexagon on Saturn etc. Etc. I'm not outright dismissive, but to treat it as anything but food for thought/entertainment is a little worrying to say the least. What do you have to go on there other than the testimony of other people who claim to have been involved or whatever?

There's no hard data avaliable to the likes of you and I on such things. Many of these ideas cannot be entirely refuted, but nor can they be confirmed either. That puts us squarely in the realm of superstition and religion.

I'm a part time discordian/khaos magus/git wizard so I do have more time than most for superstition and flights of fantasy but I steer well clear of treating any of that kind of think as objective fact.

The realms of materialism and idealism should stay entirely separate except when they converge and compliment each other e.g. If I can imagine a black swan and then go out and find one (after performing the necessary experiments to disprove any other possible explanations for why it might seem black) then I can tell others that black swans are definitely a real thing. The same cannot be said for say the flying spaghetti monster or the chocolate tea pot orbiting the sun even though believing in such things makes my life more interesting under certain circumstances (and such liberated thought processes can eventually lead to as yet undiscovered ideas which may indeed prove to be "true" or helpful).

"Given all theories of the universe are absurd, it is better to speak in the language of one which Is patently absurd so as to mortify the metaphysical man." -Alaistair Crowley

Translation: if your going to indulge stuff like this don't take it or yourself too seriously or you will go mental!

Praise be to pope Bob!
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While I agree with your sentiment, I think there's also the issue that what's "perceived" as barely over etc. I've done filming like this for PSA's where we can't actually portray anyone committing an infraction.

But the point the video is making is pretty clear: if someone else makes a mistake, you better be prepared. You may not be at fault, but you're now involved, so do something that'll help minimize the casualties.

Additionally, perceived speed and actual speed can vary greatly. If driver A is used to driving that road at X speed, but driver B drives X+Y, then driver A will overestimate the amount of time they have.

Lastly, 10 MPH in speed makes a huge difference in impact velocities. Used to be pretty standard to say you'll walk away from 50, but carried away at 60.

Well, technically speaking, I think the faster human free fall was around 800mph, unaided by propulsion. It was a matter of being in the right angle and wearing the right fabrics…. and the right altitude. So realistically speaking, they *could* parachute insert a lot faster than terminal velocity . . . If they tried hard enough.

If we're going to criticize the realism of it: How about the fact that the paratroopers were obviously falling several times faster than terminal velocity?

And also the fact that it's another American Godzilla (cause what could go wrong?)

Just an educated guess but I suspect it's a tiny correction for wind drift which has been exaggerated by the camera angle.

The effects I think your referring to are called the "Coriolis" effect and "Gyro drift" and while they would have a similar effect this is seems like far too short of a range for them to come into play even at the relatively low velocity of that shell. That said its possible that with such a big round like that sabot "gyro drift" and maybe some sort of torque effect from leaving the barrel might be at work...

Gyro drift is due to the fact that the spinning bullet/shell starts to be pulled out of line by gravity causing the originally stable oscillation to slowly get knocked out of whack dragging the nose of the round out of line causing the round to pull slightly towards the direction it's spinning (though with a stable modern round this is very very subtle and only really comes into play at at least 1-2mile plus ranges).

The Coriolis effect is due to the fact that the earth itself is spinning. Over very long ranges the earth itself moves relative to the path of the round and so for 1-2mile plus shots one may need to compensate depending on the velocity and ballistic properties of the round. (this is why snipers tend to operate as a team because the maths and reference material necessary to account for all this plus standard bullet drop, variable wind conditions, atmospherics etc. etc. as well as maintaining situational awareness is a big ask for one person.)

Like I said though it seems unlikely they would have such a pronounced effect at such a relatively short range, the camera angle is definitely exaggerating what ever is going on there.


EDIT: I just watched it again, pretty sure it's just the camera angle (camera is slightly off to the left) I think the shell looks like it's actually travelling dead straight.

Or a ping pong ball... propelled at speed to crushing velocity.

They are flung in the air with high velocity and they exhibit impressive control over their posture.

Essentially my guess is that the bullet can only transfer so much kinetic energy to accelerate the block upwards. Above that threshold it finds other ways of disposing of this energy. Why this threshold/diminishing return might exist idk.

So yeah, I think there must be some change in the efficiency of the transfer of energy in the two examples. Does smacking the bullet right in the centre create more sound? Does the bullet deform/heat up more in the first example because the block simple can't get out of the way fast enough? You'd think that spinning a block would take comparitively little energy compared to all those other inefficiencies. Perhaps if you were to increase the velocity of the bullet you might not see that large of a difference in the height it rises - rather the block would sustain more damage, the slug would pancake more etc etc.

It does seem raher counter-intuitive though. I'd like to know the explanation.

I thought you might be overestimating the force of a thrown baseball as compared to the steel ball bearing, so I tried to do some research and run numbers to compare.

Some googling says a baseball should weigh 5-5.25 ounces (about 1/3 of a pound).

Another page and some quick calculations that I might have screwed up[ (4*pi*.5*.5*.5)/3*.283 ] say that the ball bearing might weigh about .15 pounds -- a bit under half of the baseball.

On the other hand, the fastest pitch ever recorded in MLB (by Nolan Ryan) was 108.1 MPH or 158.5 feet per second. Harder to find data on "muzzle" velocity of a slingshot, but this page suggests that some people claim some slingshot projectiles can travel at 300 feet per second, but he argues that 180 to 200 fps is probably a more realistic high end for a .50 caliber lead ball (which would probably/possibly? be heavier than the 1" steel ball since lead is more dense). Anyway, there is at the very least a slight advantage to the slingshot here as compared to the fastest pitch ever recorded in MLB. Considering the draw length and pull strength of the slingshot in the video, I'd say it is probably actually much faster than the conservative 180-200 fps number from that page.

So then you've got @cosmovitelli 's formula (mass times velocity squared). The mass of the baseball is probably double that of the steel ball, but the velocity is probably 25-90% faster (or even more) and then squared. That probably overcomes the disadvantage in mass and then some.

Then again, this is all fairly academic as you suggested because the lethality of the bullets/projectiles is dependent on them being small enough to puncture, tear flesh, break/shatter bones, etc. Apply that kinetic energy to a very small impact site. However, in spite of its large size, I bet that steel ball could do a lot of damage given its kinetic energy -- which is what I would take away from their claims of it "hitting harder". I wouldn't want to stand in front of a Nolan Ryan fastball either, but given the choice between that and the slung steel ball... I'd take the plunk and have somebody take my base for me.

The slingshot does "hit harder" i.e. impart more momentum into the target and thus more likely to knock you down.
Intuitively this seems like it would therefore cause the most damage and for several 100 years this was the prevailing logic with muskets and cannonballs.

So much so in fact that when Charles Whitworth first introduced his rifle it was dismissed by the British army partly for having too small of a bullet. Whitworth used a smaller more stable round for its increased range and accuracy/stability (though there were also concerns about "muzzle fouling" and slower reload time).
It was believed at the time that the larger (slower) much less accurate bullets from the Enfield were more effective at actually injuring enemy soldiers, but history later demonstrated that speed and penetration can have just as much (if not more) effect on soft bodies than sheer mass and momentum.

Simply put, that large slingshot round would likely knock you to the floor in the same was as an MMA fighter landing a roundhouse square in your guts would. It might even penetrate the skin a bit and embed itself in you. What it won't do however is travel through your soft tissues at high velocity and create a large "temporary cavity" which is how most firearms do their real damage.

The 9mm etc. don't carry as much overall energy as the slingshot, but they do deliver it to a soft target much more effectively (that is to say lethally). A much more informative test would have been to fire them into ballistic clay, this would have highlighted the differences between speed, momentum and penetration much more clearly. The slingshot would leave a massive dint, the bullets would leave tunnels.

That said, the point they are making does stand to some extent. If you used that slingshot on someone that was trying to shoot you there is a good chance you'd knock them down (or at least stop them taking an aimed shot back for a few seconds). Hell you might even hospitalise them with a good shot!

It's not fair to say that the slingshot is a more "powerful" weapon but I think they did clearly demonstrate that it's a viable alternative under some circumstances. In fact for defending yourself in your own home etc. it might even be better!

Little/no risk of collateral damage (unless you miss really badly)
Very cheap
Would put most people on the floor with one good hit
No firearms licence or background checks needed
More difficult for a child to misuse (Most kids would lack the strength)
Enemy wouldn't expect it
Much less likely to kill
etc. etc.

Hell I'd get one myself if UK law wouldn't fk me over for using it.
It's illegal here to use a weapon specifically intended or kept for defense. i.e. if you grab a random object like a chair and beat up an intruder that's ok, if you have a baseball bat etc. by your bedside for expressly this purpose then it's not.
Handy then that one of my broken computer chairs happens to contain a loose 1ft long iron bar. Naturally I'd never even consider using such a thing violently, but who knows what might come to hand when faced with an intruder

(Seriously though, as broken furniture its a viable means of defence, if I kept it by my bedside as a "weapon" I'd be breaking the letter of the law by using it. Fucking stupid!)