Running into Things [3.5]

[Mushroom Ninja]

Disclaimer: Many catgirls have died to bring us this information...

For a while now, I have been troubled by an interesting question. This question is "If a character is moving very fast and runs into something, will any damage be dealt?" For a while I pondered this. Then I realized that if I were to calculate the character's velocity at impact time, and compare that to the instantaneous velocity at time of impact for something falling, by the rules section, "Damage from Falling Objects", I could determine how much damage would be dealt.

Here's the math:

Let's assume that my character, a wizard, weighed 200 pounds (with equipment).

He gets on his phantom steed (240 ft movement) and uses the run option (4x movement) to run into a dragon. His velocity on impact is 160 ft/sec.

240 ft movement x 4 (run modifier) = 960 ft
because this movement is moved over a course of a round, we divide this by 6 to get 160 ft/sec.

Now, to calculate the height that an item impacting ground at this velocity would have to be at, we're going to need to use some calculus.

The position of falling objects formula is height = -16(time)^2 + (initial height). To find the velocity of a falling object at any given point, we're going to have to take the 1st derivative of that equation and get velocity = -32(time).

Now, we're trying to find the height of something that, when hitting the ground, has a velocity of 160 ft/sec. Because velocity is directional, I'm going to turn that into -160ft/sec so we don't come up with a negative time. This isn't necessary, but I'm going to do it anyway because I like positive numbers.

Okay, so we need to plug -160 ft/sec into the instantaneous velocity formula. This gives us (-160) = -32(time). With just a little simple algebra, we get (time) = 5.

From here, we just need to plug this value back into the position function, using 0 as the final height:

0= -16(5)^2 + (initial height)

By a little more algebra, we get the initial height to equal 400 feet!

This means that velocity of my wizard when he runs into the dragon is equal to the velocity of an object when it hits the ground after a 400 foot fall.

So, by the rules found here, we see that my 200 lb wizard is doing about 20d6 damage. Nifty!

The one problem is, of course, due to those silly laws of physics, my wizard would also take 20d6 damage.

Just thought others might want to know...

P.S.: If I've got my math wrong, please tell me so.

[Sstoopidtallkid]

Awesome level 12 touch attack. Especially with a Familiar or Follower who you can have ride the mount instead of you.

[Mushroom Ninja]

Now that's progressive!

[Pie Guy]

Or you could get the meatshie- I mean fighter, to do it.

[Iku Rex]

[Lord Herman]

My calculations of running into people on foot:

In 3.5:

(30ft) * (4) / (6 seconds) = 20 ft per second
20ft/s / 32ft/s² = 0.625 seconds
16ft/s² * (0.625 seconds)^2 = 6.25 feet

In 4E:

(40ft) * (2) / (6 seconds) = 13 1/3 ft per second
13 1/3ft/s / 32ft/s² = 0.416 seconds
16ft/s² * (0.416 seconds)^2 = 2.77 feet

No damage in either case

[Yehomer]

Actually, the 20d6 max falling damage is because of the top falling speed of an object. Since you don't have that problem while riding a mount, you should take the full 40d6 damamge :X

[sleepy]

You could get technical here and say since your Run option can begin and end at a complete stop, your distance over time for the round is averaging your speed which peaked at twice 160m/s, so your top burst speed is 320m/s for... what, 80d6?

Of course, your DM will rule, correctly and fairly, that accelerating to mach 1 in 3 seconds is the equivilent of jumping in front of a mac truck as far as your neck and innards are concerned.


(edit: this speed actually breaches the sound barrier at around -18c/0F and below. Travel to frostfel and make sonic booms with your phantom steed today!)

[Lord Herman]

We'll need to ascertain how much momentum equates to how much damage, assuming a non-pointy, humanoid object.

The terminal velocity of the average adventurer is:

sqrt(2mg/ρAC_d)

m = mass = about 140 kg, assuming full gear and armour on a well-muscled male
g = gravitational acceleration = 9.8 m/s²
ρ = air density = 1.204 kg/m³
A = projected area = about 1.5 m², considering size of gear and armour, assuming adventurer isn't assuming a streamlined position
C_d = drag coefficient = 1.5, slightly above the average for a person, accounting for gear that sticks out

That makes:

sqrt(2 * 140 * 9.8 / 1.204 * 1.5 * 1.5) = 32.8 m/s

With the assumed mass of the adventurer, the momentum is:

32.8 m/s * 140 kg = 4456 Ns

This amount of momentum equals 20d6 falling damage. That means one die of damage equals 223 Ns of momentum.

Now, an adventurer, running into someone at full speed, has a momentum of:

140 kg * 30 ft * 0.3 m/ft * 4 / 6 seconds = 840 Ns

840 Ns / 223 Ns/d6 = 3.8d6 damage

...well, it's more damage than I got in my last post.

[Pie Guy]

840 Ns / 223 Ns/d6 = 3.8d6 damage

Someone pass the d5

[FMArthur]

But what are the applications for stylish Power Attacks? Do we add this if we're hitting them with a weapon? Does the weapon hit, and then this thing resolves after? It is imperative that this be applied to squeeze every last bit of awesome out of certain attacks.

[Pie Guy]

Also, use a spear and charge.

[Mushroom Ninja]

Also, use a spear and charge.

hmm, how do we incorporate pointy things attatched to the adventurer into the damage?

[Sstoopidtallkid]

hmm, how do we incorporate pointy things attatched to the adventurer into the damage?

Armor Spikes, including Spiked Barding for the mount. You don't want to add an attack roll to this.

[bosssmiley]

Disclaimer: Many catgirls have died to bring us this information...

For a while now, I have been troubled by an interesting question. This question is "If a character is moving very fast and runs into something, will any damage be dealt?"

Only if you have the powerful charge ability, or if you bull rush someone into a wall, or if the spell description says so.

As a quick DM call, I'd say that running into a wall does 1d4 nonlethal damage and leaves you dazed for a few rounds. Not something you want to make a habit of in high-risk environments then.

[Sstoopidtallkid]

Only if you have the powerful charge ability, or if you bull rush someone into a wall, or if the spell description says so.

As a quick DM call, I'd say that running into a wall does 1d4 nonlethal damage and leaves you dazed for a few rounds. Not something you want to make a habit of in high-risk environments then.

He's not running into a wall. He's summoning a magic horse and having it run into a wall. The horse has a move of 240, so it can run at 109.1 miles/hour. You can't tell me that won't hurt.

[Ravens_cry]

Yeah, this whole thread should keep the vermin at bay.
Death to Cat Girls!

[bosssmiley]

He's not running into a wall. He's summoning a magic horse and having it run into a wall. The horse has a move of 240, so it can run at 109.1 miles/hour. You can't tell me that won't hurt.

110mph horse?

I think that's massive damage territory then. Say, 1d6 damage/10mph. Ref save to dodge.

[Ravens_cry]

Of course, since this is Heroic Fantasy, he could just jump off the horse and roll, that always works in the movies.

[jcsw]

Okay. Now to optimize the build!

Assuming terminal velocity is negligible here. (Much more so than when falling at least...)

First lets get the multiplier as high as possible.
Base Run: x4
Run Feat gives you x5
Travel Devotion lets you move once as a swift action: x6.

Now to reach as much speed as you possibly can.
Class: Cleric
Lets use Footsteps of the Divine, a spell from complete champion. If you're a cleric of Fharlanghn, (which is a god who *would* support such tactics, and also grants travel devotion...) you get +50ft movespeed...

However, you can end the spell at the end of the turn to gain (Rounds Remaining)x10ft bonus speed, in addition to the +50, this turn.

At CL 12, the same CL as you use to gain 240 movement with a phantom steed, this is a total of 110+50 speed. This is boring... so instead...

DMM persist. 14400 round duration means a total speed of 30(Base)+50(Base Bonus)+144000 feet = 144080 ft base speed.

x6 modifier, divided by 6 seconds... so 144080ft/second. I hate imperial, so 43916 m/s

Using the calculations... v=at. Where a is 10kg/N... t=4392s
s=(0.5)(10)(4392)^2=96448320meters=312737743ft
Which means approximately 3,000,000d6 damage.

[Lord Herman]

Now all we have to do is prevent the character from taking that same amount of damage. Are there any ways to prevent all damage for one round?

[The Glyphstone]

There's Timeless Body.

[Xallace]

Now all we have to do is prevent the character from taking that same amount of damage. Are there any ways to prevent all damage for one round?

Yeah, there's a feat that lets barbarians do it in PHBII. You could also get someone to cast Surelife on you keyed to this specific situation (though that wouldn't stop the damage, just stop it from killing you).

[Telonius]

Now all we have to do is prevent the character from taking that same amount of damage. Are there any ways to prevent all damage for one round?

That was my thought as well. The rules never say how much damage the ground takes when the falling person hits it... do they?

[Duke of URL]

Someone pass the d5

Sorry... in D&D, we round down.

[Epinephrine]

The stance Immortal Fortitude could let you survive the collision, but it wouldn't prevent all the damage, just enough to keep you conscious.

That said, a 70kg person's impact isn't even equivalent to a kiltoton of TNT, even at 130 times the speed of sound. 68 billion Joules is only about 1.6% of a kiloton.

First, you want to be bigger (more massive), so you want to change into a really dense/big form (sure, mass is only linear, but it's still important). Some combination of Enlarge and Iron Body, or a polymorph into some large-sized dense creature could boost mass by a factor of 80 or so (x8 for enlarge, x10 for Iron Body). That puts the energy up over a kiloton.

You need some way to move a bit faster - perhaps a few times that speed. The speed boost sounds like it is only lasting one round, else one could use a Swiftblade's power. A 10th level Swiftblade could subsume a 9th level version of the Haste spell, getting 4 rounds of extra actions as a result. Provided one could cast the subsumed haste as a quick action (using a very pricy rod of metamagic?) one could get 5 full round actions (4 of them with swift actions too). If one had the ability to move at that insane rate in each of those rounds, you could nearly quintuple your speed, boosting energy by a factor of 25? That'd be more energy than Fat Man released. Of course, you've got to be able to get the insane speed on each of those rounds, which would require casting and releasing a copy of Footsteps of the Divine each round, as a swift action? It's sounding epic, but that's a lot of possible speed.

[jcsw]

Surelife

Just pick: Deadly Collisions

Alternatively, buy/craft a contingent revivify.

As for additionally multiplying the number... belt of battle. Spend three charges for another Run action. (If you use this you can't use Travel Devotion, since activating is a swift action...)

[koldstare]

IIRC falling damage is classifed as bludgeoning, and since lich are immune to bludgeoning damage...

[Animefunkmaster]

Movement in dnd isn't always constant, I think it is assumed you are not just running into someone (that's what slam attacks are for). Theoretically, I can see this being used for a trap or something that interrupts a charge/run, but running into an enemy as a form of offense is a tad bit silly.

With that I present the Commoner Hireling Bucket Brigade Chicken Death Star.
PC: Anyone that can organize large groups of individuals. (Thrallherd works well when available).

Ingredients:
-Hirelings untrained (1sp per 5feet essentially, worried about dropping the item, go with two hirelings per 5ft)
-1 chicken infested commoner (ammunition)
-Line them up shoulder to shoulder. Organize them so that they all ready an action to hand a chicken from the person on there right to the person on there left. Last person uses a free action to drop the item. The velocity of that chicken is only limited by the number of hirelings purchased.
-Fabricate some kind of intricate device to aim your chain gang of hirelings.
-???
-Profit

Alternatively The original man powered lightning rail consisted of miles and miles of hirelings who would ready an action to pass an object from one person to another. Those objects happened to be connected to a small car for passengers. These cars would quickly travel around eberron at nearly light speed. Then the hirelings went on strike and the wizard in HR got fed up and fired them all, deciding that magic will solve all his problems (yet for some reason, never learned dominate or charm person)

[Suzuro]

Just make sure you have a scarab of invulnerability, and you can...pretty much kill anything....ever...


-Suzuro