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Karthas077
2011-10-07, 08:08 PM
10 foot goliath beetle would weigh just over 2 metric tons. (around 4685 lbs)

According to the size rules, a large beetle's top speed (with the feat "Run") is 37.5 feet/ second or 11.43 meters/ second.

A falling object falling for 10 feet has a velocity of 9.8 meters/second.

The falling object rule for 3.5 is 1d6 per 200 pounds and every 10 feet.

A 4000 pound creature charging at 11.43 m/s SHOULD do the 20d6 max of falling damage... but it doesn't.

So is the falling damage wrong? or is the damage you get for charging wrong?

Or are we just going to hand wave this as a result of the fact that it's an RPG and these damage values are "Abstractions" of real life concepts and therefore can't be compared like this?

Glimbur
2011-10-07, 08:18 PM
Do we want real physics or in-game rules?

In game, if every charge from large fast monsters did stupid big piles of damage then the name of the game would be "never get charged". It narrows the available options by making one choice so good. For a more balanced way to implement this, look at the Dungeoncrasher Fighter substitution levels in Dungeonscape.

For a physics approach, consider that when a beetle lands on you the ground prevents you from moving with it, while when a beetle charges you it can push you back which reduces the damage done.

Mastikator
2011-10-07, 08:20 PM
A falling object squishes you between the object and the ground, if the beetle falls on you I think it would do 20d6 damage though.

Edit: Ninja'd!

NMBLNG
2011-10-07, 08:46 PM
Also, were a charging creature to ram you into a wall or something, it would also deal damage to itself at that speed.

2011-10-07, 09:14 PM
10 foot goliath beetle would weigh just over 2 metric tons. (around 4685 lbs)

According to the size rules, a large beetle's top speed (with the feat "Run") is 37.5 feet/ second or 11.43 meters/ second.

A falling object falling for 10 feet has a velocity of 9.8 meters/second.

The falling object rule for 3.5 is 1d6 per 200 pounds and every 10 feet.

A 4000 pound creature charging at 11.43 m/s SHOULD do the 20d6 max of falling damage... but it doesn't.

So is the falling damage wrong? or is the damage you get for charging wrong?

Or are we just going to hand wave this as a result of the fact that it's an RPG and these damage values are "Abstractions" of real life concepts and therefore can't be compared like this?

Because an object falling for the distance you need for max falling damage has a MUCH higher velocity than 9.8 m/s. If it were just 9.8 m/s (the velocity you attain after 1 second of falling), then you're talking something like 30 feet, or only 3d6.

Seb Wiers
2011-10-07, 10:36 PM
A falling object falling for 10 feet has a velocity of 9.8 meters/second.

No, it does not. Falling 10 feet (3 meters for easy math) only gets you up to about 7.2 m/s.

Your 11.43 m/s rhino has effectively "fallen" only 6.7 m, or 22 feet.

Still enough for the 20d6 damage, except the problem is this - injury wise, there shouldn't be difference between being charged by the rhino, and you falling on it from 22 feet up. The physics of the collision are identical in both cases. But the math you used for damage gives VERY different results in those two cases.

I'd say its falling that doesn't work, not charging.

tyckspoon
2011-10-07, 11:01 PM
For a physics approach, consider that when a beetle lands on you the ground prevents you from moving with it, while when a beetle charges you it can push you back which reduces the damage done.

For a physics approach you don't get insects that big, because their body plans don't scale up that high- the square-cube law of making things bigger means a Large insect, built out of the same things and to the same design a tiny one is, won't be able to support itself.

Karthas077
2011-10-08, 02:58 AM
I used the square cube law to get a 10 foot beetle's approximate weight.

For those of you who pointed out that being hit horizontally by a large/fast moving object allows you to absorb some of the force into your own velocity, that is a very excellent point, and I think explains the difference in damage adequately enough for me to still be semi-happy with both the falling object rules and the damage of a charge.

Also, I realize I'm a complete derp, and that I wasn't converting my meters to feet etc. >_> bad maths ftw

Either way it doesn't matter TOO much because you hit the 20d6 max with weight alone at 10 feet, so being 20 something feet higher up won't change anything.

FlyingScanian
2011-10-08, 10:26 AM
Either way it doesn't matter TOO much because you hit the 20d6 max with weight alone at 10 feet, so being 20 something feet higher up won't change anything.

Wait, what? Falling damage is 1d6 per 10 feet fallen... how does that equate to 20d6 over 10 feet?

TheCountAlucard
2011-10-08, 11:30 AM
Wait, what? Falling damage is 1d6 per 10 feet fallen... how does that equate to 20d6 over 10 feet?Weight's also a factor, there.

Anxe
2011-10-08, 12:49 PM
Also, wouldn't the beetle be taking the same amount of damage if it did something like that?

Mikeavelli
2011-10-08, 02:16 PM
Yeup. Bigger creatures already get strength bonuses - both for the size increase and because the designers give big monsters large base strength - which allows them to do more damage with all that mass. That represents the additional damage they can do without injuring themselves in the process.

Slamming into someone with the full weight of "falling damage" would have the exact same effect as, well, falling on them. Both creatures take damage from the fall.

Also, should be impossible except for a few stupidly suicidal or undead creatures.

Lord.Sorasen
2011-10-08, 03:14 PM
A few things to add that I think have been missed.

One is that D&D 3.5 is a game, and real life physics are, when taken in their entirety, very complicated. So the game is streamlined at the expense of accuracy. There are all sorts of things that the equation you gave doesn't account for. For instance, D&D almost entirely ignores acceleration (exceptions being the 15 feet necessary for a charge or the increased damage for a fall). We have no idea how fast the beetle is moving at any single point in its run, so we can't necessarily take the average velocity.

Another thing is that D&D doesn't allow an attack with a run, and they specifically define a charge as less than a full on sprint. What it implies is that while one could run a certain speed and use that speed to attack, sprinting takes a certain amount of motion that would make striking in any way almost impossible. The monster might be able to just straight rush, but there's such a good chance that it would damage itself that the creators didn't think it was worth it to include such an option.

As someone else mentioned, there's the aspect of slamming into the ground vs. slamming backwards.

D&D uses strength to define how much force was put into an attack. It tries to avoid using things like speed because they aren't controllable by the players to much extent (most classes have 20-40 speed if not worked on.)

Long story short, yes, it's an abstraction. The two very different modes of damage are handled by different equations, and it doesn't work to simply substitute the variables.

faceroll
2011-10-08, 07:32 PM
For a physics approach you don't get insects that big, because their body plans don't scale up that high- the square-cube law of making things bigger means a Large insect, built out of the same things and to the same design a tiny one is, won't be able to support itself.

By the same argument, you could never get any mammals much larger than a shrew, due to the square-cube law.

IRL, terrestrial arthropods are size limited due to issues of competition with vertebrates and evolutionary history.

Eric Tolle
2011-10-08, 08:31 PM
The anatomy of vertebrates scales up much better than that of invertebrates.

Necroticplague
2011-10-08, 09:05 PM
By the same argument, you could never get any mammals much larger than a shrew, due to the square-cube law.

IRL, terrestrial arthropods are size limited due to issues of competition with vertebrates and evolutionary history.

No, it simply that some anatomies scale better than others , the reason the biggest single-celled organism is a barely visible speck, while blue whales have hearts the size of a minivan.

2011-10-08, 09:12 PM
Skeletons were one of nature's better ideas when it came to making big animals, that's for sure.

faceroll
2011-10-09, 01:25 AM
The anatomy of vertebrates scales up much better than that of invertebrates.

No, it simply that some anatomies scale better than others , the reason the biggest single-celled organism is a barely visible speck, while blue whales have hearts the size of a minivan.

What about the anatomy of invertebrates doesn't scale well?

Halna LeGavilk
2011-10-09, 01:29 AM
What about the anatomy of invertebrates doesn't scale well?

Exoskeleton, I believe. As it gets bigger, it weighs far too much and ends up crushing the organs, as it weighs so much.

faceroll
2011-10-09, 01:48 AM
Exoskeleton, I believe. As it gets bigger, it weighs far too much and ends up crushing the organs, as it weighs so much.

Besides scleterotized/calcium carbonate impregnated chitin being extremely durable, strong, and light, the structural design of a chamber with things inside it prevents the chamber from putting force on its contents.

Then you also get stuff without any exoskeletons at all, like worms.

The issues with real life inverts being big is an issue of competition with vertebrates, not that being an invertebrate has some physical limitation on size.

Invertebrates, in general, have primitive circulatory, pulmonary, and nervous systems. Even highly evolved invertebrate versions of these systems don't compete well when scaled up.

Inverts are saddled with hundreds of millions of years of evolution adapting their systems for being small. It doesn't mean that they cannot get big, given enough time, but that given that getting big would make them less competitive, they do not. Remove the competition, and in 500my, you'd see coleopteran descendents the size of buses.

You could easily have something that looked like a giant spider or a giant beetle, but internally, was way different. It's have a true circulatory system and actual lungs. It'd probably be endothermic. It'd have heavier composite materials in its skeleton, more articulation at joints, and more chambers within its carapace to support organ systems.

Worira
2011-10-09, 06:02 AM
Note that the topic creator didn't say "10-foot arthropod", he said "10-foot goliath beetle". And no, just scaling a goliath beetle to ten feet would not produce a viable organism.

Also, unless I'm mistaken, spiracles and tracheal tubes set pretty rigid restraints on the possible size of insects. It's not that they aren't efficient enough to compete with the respiratory system of larger mammals, it's that they aren't efficient enough to keep the creature alive at all past a certain size.

EDIT: Oh wait, you already addressed that. Herp derp, me gots big smarts.

That said, I will point out that tyckspoon actually said
For a physics approach you don't get insects that big, because their body plans don't scale up that high- the square-cube law of making things bigger means a Large insect, built out of the same things and to the same design a tiny one is, won't be able to support itself.

faceroll
2011-10-09, 07:16 AM
Note that the topic creator didn't say "10-foot arthropod", he said "10-foot goliath beetle". And no, just scaling a goliath beetle to ten feet would not produce a viable organism.

While true, that does not preclude the existence of an organism that superficially resembles a 10-foot goliath beetle, but is no more a coleopteran than brachyuran is, though both would be classified as arthropods.

I find the observation that "you can't just scale things up and get a functioning result herp derp" rather trite. You also can't just scale a human up and get a 20 foot tall, 8,000 lb giant. He'd die from over heating and his heart would be too small relative to the size of his body. And his ankles just wouldn't be able to support that mass.

Also, unless I'm mistaken, spiracles and tracheal tubes set pretty rigid restraints on the possible size of insects. It's not that they aren't efficient enough to compete with the respiratory system of larger mammals, it's that they aren't efficient enough to keep the creature alive at all past a certain size.

The passive diffusion system of insects are very efficient for their size. At larger body sizes, you'd get tissue death unless you were pretty much vegetative. That being said, recent evidence in grasshoppers and I believe wasps shows that, contrary to a long-standing belief that insects breathe by passive diffusion, there's some sort of active mechanism that brings O2 into their systems faster.

The hemocoel of most arthropods would also be a limiting factor in size. As they are, the pulmonary and respiratory systems of insects wouldn't function well (or at all) if you made big versions of small things identical in every way, just bigger. In real life, evolving entire new organ systems to compete with a 300 million year old clade just isn't going to happen.

For a physics approach you don't get insects that big, because their body plans don't scale up that high- the square-cube law of making things bigger means a Large insect, built out of the same things and to the same design a tiny one is, won't be able to support itself.

That's self evident. Elk aren't built out of the same things and to the same design mouse deer are, but they're both deer. Why would it be expected that giant vermin are identical in every way to their diminutive cousins?

Necroticplague
2011-10-09, 07:45 AM
I find the observation that "you can't just scale things up and get a functioning result herp derp" rather trite. You also can't just scale a human up and get a 20 foot tall, 8,000 lb giant. He'd die from over heating and his heart would be too small relative to the size of his body. And his ankles just wouldn't be able to support that mass.

True, I think the basic problem is that all organisms are already as large as their personal biology allows, so getting bigger requires some changes to get bigger, this works for all organisms. You can't simply multiply dimensions to get an existing organism, you have to make a change (or more likely, several changes).

Jayabalard
2011-10-11, 04:30 PM
No, it does not. Falling 10 feet (3 meters for easy math) only gets you up to about 7.2 m/s.Actually, it's ~7.72 m/s

vave = (v + v0) / 2

solve for v
v = 2 * vave - v0

t= delta X /vave
vave = delta X / t

substitute and you get
v = 2 * delta X / t - v0

t= (v - v0) / a

substitute again and you get
v = 2 * delta X / ((v - v0) / a) - v0

v0 = 0 (in a fall, from rest)

so
v = 2 * delta X / (v / a)

solve for v:
v2 = 2 delta X * a
v= sqrt(2 * 10feet * 9.8 m/s^2) = 7.72 m/s (http://www.google.com/search?q=sqrt%282+*+10feet+*+9.8+m%2Fs%5E2%29&ie=UTF-8)

let me know if there's something wrong with my math here.

Your 11.43 m/s rhino has effectively "fallen" only 6.7 m, or 22 feet.apples to oranges. This is comparing average velocity (displacement / time) with the end velocity of a constant acceleration.

NichG
2011-10-11, 07:22 PM
Think about it this way. A person falling and hitting the ground at 7.72 m/s is exactly the same as a stationary person being bodyslammed at 7.72 m/s by the ground, effectively a beetle of infinite mass (or at least the mass of the planet). That does whatever damage it does. Slight differences due to the softness of the substance you land on, but those aren't modeled by D&D.

So the maximum damage that one should take from a sideways collision is always less than or equal to that caused a fall that would net you that collision speed. The reason is that the thing that hurts you is that you have to change your own velocity - the velocity of the infinite beetle doesn't change at all.

Being pinned between a heavy object and the ground on the other hand is a lot worse, because now your body is transmitting whatever force is necessary to stop the heavy object. If that heavy object is an infinite beetle, you're in trouble.

Heliomance
2011-10-11, 07:33 PM
Incidentally, I would note that falling damage from weight doesn't cap at 20d6. Only the damage from height caps.

TSED
2011-10-12, 03:42 AM
Think about it this way. A person falling and hitting the ground at 7.72 m/s is exactly the same as a stationary person being bodyslammed at 7.72 m/s by the ground, effectively a beetle of infinite mass (or at least the mass of the planet). That does whatever damage it does. Slight differences due to the softness of the substance you land on, but those aren't modeled by D&D.

So the maximum damage that one should take from a sideways collision is always less than or equal to that caused a fall that would net you that collision speed. The reason is that the thing that hurts you is that you have to change your own velocity - the velocity of the infinite beetle doesn't change at all.

Being pinned between a heavy object and the ground on the other hand is a lot worse, because now your body is transmitting whatever force is necessary to stop the heavy object. If that heavy object is an infinite beetle, you're in trouble.

... "Infinite beetle" would make such an awesome monster. Sure, it'd be some sort of epic-level tarrasque clone, but you could totally start a campaign over trying desperately to find some way to stop it. Just write "yes" on all of its strength checks, and it can start doing stuff like ploughing through force walls, or moving the entire world relative to the force wall. And NO ONE wants to get hit by that thing. Ever.

On the other hand, players might get sick of that after a few good ideas turn out to not work, and you'd need some sort of "MAGIC!!!" explanation for why the infinite beetle doesn't collapse into a black hole, but hey. Infinite beetle.

Mastikator
2011-10-12, 08:49 AM
By the same argument, you could never get any mammals much larger than a shrew, due to the square-cube law.

IRL, terrestrial arthropods are size limited due to issues of competition with vertebrates and evolutionary history.

Mammals have endoskeleton rather than exoskeleton, but if you scale up a human it will too have problems with its own weigh, people that really big (say, 250 cm) have skeletal problems (due to weight). If you scale a human to say 5 or 6 meters the human would have serious issues even moving and would probably die.
It's also the reason why really big animals, like the elephant, can't jump or stand up if it falls. Whales are only able to be as big as they are because they're in the ocean, where it doesn't have to stand on legs.

hamishspence
2011-10-12, 09:42 AM
Quadrupeds got quite a bit bigger than elephants though- giant dinosaurs like Argentinosaurus- though they tended to be light for their volume- hollow bones, air sacs.

Solaris
2011-10-12, 01:09 PM
No, it simply that some anatomies scale better than others , the reason the biggest single-celled organism is a barely visible speck, while blue whales have hearts the size of a minivan.

Grape, actually. You get strange things in the deep sea.

TheCountAlucard
2011-10-12, 01:20 PM
Grape, actually.[citation needed]

With no offense intended, everything I've seen so far has indicated that this is assuredly not the case.

Stegyre
2011-10-12, 02:39 PM
[citation needed]

With no offense intended, everything I've seen so far has indicated that this is assuredly not the case.
Perhaps a very, very big grape? (http://www.buzzfeed.com/daves4/the-size-of-a-blue-whales-heart-cg3):smallwink:

DefKab
2011-10-12, 03:14 PM
[citation needed]

With no offense intended, everything I've seen so far has indicated that this is assuredly not the case.

I think he meant the single celled organism... (http://www.just2smart.com/marine-biology/what-is-the-world-s-largest-single-celled-organism.html)

Necroticplague
2011-10-12, 04:24 PM
Sorry, I stand severely corrected on the single cell-organism (I thought the biggest was ameoba chaos chaos, a tiny speck in pond water). I think I was thinking of the biggest single-cell prokayote (though I'm probably wrong in that case to). Thinking back to it I feel silly, remembering from long ago when someone told me an unfertilized egg is single large cell, so my own retrovision proves me wrong by a fair margin.