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How far would you fall in one round assuming you started falling this round, and were high enough that you did not hit anything? Would this follow the math, or is there a rule written somewhere I'm missing?

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3 Answers

up vote 19 down vote accepted

Keep in mind that human terminal velocity peaks around 53-56m/s... about 170-183 ft/sec... or about 1100 ft/round. It should take, at 32ft/sec (which is close enough for this), it's about 5.7 sec...

ragdoll Mode Terminal Velocity calcs
S1: .... 16 ft .. 32 ft/s ... 192 ft/r
S2: .... 64 ft .. 64 ft/s ... 384 ft/r
S3: ... 144 ft .. 96 ft/s ... 576 ft/r
S4: ... 256 ft . 128 ft/s ... 768 ft/r
S5: ... 400 ft . 162 ft/s ... 972 ft/r
s6: ... 574 ft . 183 ft/s .. 1098 ft/r .. terminal velocity

So, since terminal velocity is hit during turn 1... half that is the distance covered in turn 1...

So turn 1 should be to about 550 feet, and each turn thereafter another 1100 feet.

Now, peak recorded speed was about 125mph in random posture, or about 210mph in bullet posture... for about 308 ft/sec...

so, if the character's in bullet mode...

Bullet Mode Terminal Velocity calcs
S1: .... 16 ft .. 32 ft/s ... 192 ft/r
S2: .... 64 ft .. 64 ft/s ... 384 ft/r
S3: ... 144 ft .. 96 ft/s ... 576 ft/r
S4: ... 256 ft . 128 ft/s ... 768 ft/r
S5: ... 400 ft . 162 ft/s ... 972 ft/r
s6: ... 576 ft . 194 ft/s .. 1164 ft/r __ exceeds ragdoll TV
S7: ... 784 ft . 224 ft/s .. 1344 ft/r
S8: .. 1024 ft . 256 ft/s .. 1536 ft/r
S9: .. 1296 ft . 288 ft/s .. 1728 ft/r
S10: . 1600 ft . 300 ft/s .. 1800 ft/r __ terminal velocity
S11: . 1900 ft . 300 ft/s .. 1800 ft/r
S12: . 2200 ft . 300 ft/s .. 1800 ft/r

So, a little physics: falling like a ragdoll: 550' in round 1, 1100' each round after.
Falling in speed suicide dive: 550' in round 1, another 1600 in round 2, and another 1800 per round in rounds 3 and later...

For simplicity, make it 500 and 1000 in ragdoll, and 500, 1500, and 1800 for diving.

Also note the 4E DMG says 500 feet in round 1, which is about 50' short, but could be covered by not being in ragdoll, but parasol, or by a 28' per second per second gravity.

References:
http://hypertextbook.com/facts/JianHuang.shtml
http://answers.yahoo.com/question/index?qid=20080412205510AAEu62v

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Nice and thorough, from a realistic and technical standpoint. However, I think Kedearian was looking for the "official" rules-based answer. It's nice to see the rules at least have some reality-based numbers involved. –  Iszi Oct 26 '10 at 16:51
    
If the rules didn't match, it would allows us to figure the local gravity force... and since they don't... D&D world gravity is about 28 feet/sec²... instead of 32... –  aramis Oct 26 '10 at 18:46
    
Lower dnd gravity explains why elves can jump so high... –  corsiKa Oct 5 '12 at 17:22
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As a rule of thumb, a creature falls up to 500 feet during its first turn of falling.

This is from the Dungeon Master's Guide p48 under CrashingDDI also p209 in the Rules Compendium (thanks @Iszi).

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Also in the Rules Compendium, page 209. –  Iszi Oct 26 '10 at 0:08
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The math more or less follows the DMG.

According to the rules, a creature falls 100 squares (500 feet) in the first (six second) round.

According to the laws of physics, a creature falls y = 0.5 g t2 feet, where g is the acceleration due to gravity (32 ft/s2 on Earth) and t is the number of seconds in free fall. Substituting, you get 0.5 * (32 * 62), or 576 feet. Not too far off.

Fun with Fantasy Physics

If you assume the 500 feet is a law and not an approximation, you can figure out the gravitational acceleration constant for the D&D world! That is, you can solve for g in the equation. If y = 0.5 g t2, and y=500 and t=6, then 500 = 0.5 g * 62.

So in the D&D world, g=27.78 ft/s2, not 32 ft/s2 as it does on Earth. This means that it takes longer for a creature to reach terminal velocity in the fantasy world...

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What other effects would a lower gravitational constant have? Could folks jump farther? –  Pat Ludwig Oct 26 '10 at 16:10
    
@PatLudwig A person from earth could jump farther. A person native to the low-gravity environment may or may not be able to. Creatures can generally be larger, but may have lower muscle-mass. Structures require less support relative to their height and building material allowing for larger structures. Smaller flight surfaces are required for flying/gliding relative to mass. –  AceCalhoon Oct 26 '10 at 16:24
    
Actuall, DnD4.0 standing jumps seem pretty long to me... –  F. Randall Farmer Oct 26 '10 at 17:47
    
Larger creatures would be able to fly, but the change isn't so drastic to explain flying dragons. That's what magic is for. =D –  Adam Dray Oct 26 '10 at 18:53
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@Adam Dray I tried making the argument that my gnome was 0 feet tall and therefore occupied no space and was untargetable. The GM slapped me. –  dpatchery May 18 '11 at 11:44
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