head on collision relative speed

Just got your book, can't find a copy, have a cool adventure idea or story? Chat about it here.

Moderators: PEG Jodi, The Moderators

Message
Author
Roger Eberhart
Novice
Posts: 70
Joined: Mon Jun 28, 2004 8:34 pm
Location: Mission Viejo

head on collision relative speed

#1 Postby Roger Eberhart » Fri Sep 03, 2010 7:50 pm

The Savage World's rules regarding head on collisions and relative speed are wrong. Two vehicles traveling at 50mph head on is not the same as a car hitting a wall at 100mph. This is ignoring Newton's third law. They did a segment on this on Mythbusters. Check it out: http://www.dpccars.com/car-videos-10/05 ... -Force.htm

User avatar
Snate56
Legendary
Posts: 5267
Joined: Sun Jun 11, 2006 5:57 pm
Location: Monroe, Washington

#2 Postby Snate56 » Sat Sep 04, 2010 1:16 pm

Well, they still screwed up the physics, but there was enough data in the video to determine that the initial statement made was indeed, incorrect.

Now the question really is: What happens when one car is going 20mph and the other is going 50?

Shall we add the two together and divide by two?


SteveN
"And then the indians rode down upon us. They was Arapahoe, Comanche, Cheyenne..... They was only three of 'em, but Dang! They was mean!"

User avatar
Clint
Site Admin
Posts: 19317
Joined: Tue May 13, 2003 2:28 pm

#3 Postby Clint » Sat Sep 04, 2010 5:10 pm

Roger Eberhart wrote:The Savage World's rules regarding head on collisions and relative speed are wrong. Two vehicles traveling at 50mph head on is not the same as a car hitting a wall at 100mph. This is ignoring Newton's third law.


I never studied law. ;)

Really though, it's a case of fun beats physics. It's a game, not a simulation of the laws of physics. A complex system based on total speed and the individual mass and densities of the vehicles would be a bit silly when the final effect is based off a random die roll anyway.

I suppose if someone really wanted a system of that nature, then the "easiest" version would be to roll the total combined damage, and then divide it between the two vehicles based on the inverse ratio of their comparative Toughnesses.

So if a vehicle with Toughness 12 hit a vehicle with Toughness 18 head on, roll the damage for their total speed, and the Toughness 12 vehicle take 3/5 (60%) and the Toughness 18 one takes 2/5 (40%). Course, that's very simple examples, it will take a bit more to stop and figure out the ratio/percentage for a mid-szed car (11) hitting an SUV (14) in the middle of a combat and multiply that by the damage (and yeah, it's 44% and 56%).
Clint Black
Savage Worlds Core Rules Brand Manager

www.peginc.com

marshal kt
Legendary
Posts: 2656
Joined: Tue May 13, 2003 9:18 pm
Location: west palm beach, fl

#4 Postby marshal kt » Sat Sep 04, 2010 6:04 pm

Well nothing personal, but I've found alot that myth busters does is biased, so I don't believe much of what they say.
Just they 'usage and & explantions' on guns, bullets and swords was enough for me to see that they had an agenda. We're going to prove/disprove this, so how do we do it; rather than a 'is this true or not?'
"I'm Hotep"

Roger Eberhart
Novice
Posts: 70
Joined: Mon Jun 28, 2004 8:34 pm
Location: Mission Viejo

#5 Postby Roger Eberhart » Sat Sep 04, 2010 6:50 pm

I like fun, simple solutions over realism any day (the reason I play SW, not GURPS). However, when the game solution doubles the actual damage the vehicle would take, maybe it bears looking at. RPGs have been making the same physics error since the days of Car Wars.

Steve's solution of averaging the two car's speed sounds good, and not too complicated. In reality, I think the faster moving vehicle would take less of an impact, but that leads to the slippery slope of too much realism.

User avatar
Snate56
Legendary
Posts: 5267
Joined: Sun Jun 11, 2006 5:57 pm
Location: Monroe, Washington

#6 Postby Snate56 » Sun Sep 05, 2010 1:41 am

I've actually heard DOT experts make the same statement. Guess they don't watch Mythbusters...


SteveN
"And then the indians rode down upon us. They was Arapahoe, Comanche, Cheyenne..... They was only three of 'em, but Dang! They was mean!"

pneumonica
Seasoned
Posts: 140
Joined: Sat Mar 17, 2007 4:23 pm
Location: Nowhere

#7 Postby pneumonica » Sun Sep 05, 2010 7:26 pm

marshal kt wrote:Well nothing personal, but I've found alot that myth busters does is biased, so I don't believe much of what they say.
Just they 'usage and & explantions' on guns, bullets and swords was enough for me to see that they had an agenda. We're going to prove/disprove this, so how do we do it; rather than a 'is this true or not?'


I don't know. It's really great eighth-grade science.

As for the issue of vehicular impacts, in the end the difference between gameplay and reality is typically going to be marginal for game purposes. I'm going to go with simplicity on this one. It might hit high, but in all but the extreme cases it won't be so far off as to be unreasonable.
Nothing exists but you. And you are but a thought- a vagrant thought, a useless thought, a homeless thought, wandering forlorn among the empty eternities!
-Mark Twain
The Ataraxia Foundry

kaosdevice
Novice
Posts: 22
Joined: Wed Jun 16, 2010 2:55 am
Location: Kansas
Contact:

#8 Postby kaosdevice » Sun Sep 05, 2010 10:27 pm

In soviet russia YOU HIT CAR! :blam:

User avatar
SlasherEpoch
Legendary
Posts: 5625
Joined: Mon Jul 07, 2003 11:16 pm
Location: Off stage left

Re: head on collision relative speed

#9 Postby SlasherEpoch » Mon Sep 06, 2010 12:10 am

Roger Eberhart wrote:The Savage World's rules regarding head on collisions and relative speed are wrong. Two vehicles traveling at 50mph head on is not the same as a car hitting a wall at 100mph. This is ignoring Newton's third law. They did a segment on this on Mythbusters. Check it out: http://www.dpccars.com/car-videos-10/05 ... -Force.htm


Regardless, it's easier math for me the GM to just add things together.

User avatar
Clint
Site Admin
Posts: 19317
Joined: Tue May 13, 2003 2:28 pm

#10 Postby Clint » Tue Sep 07, 2010 8:58 am

Actually, on review, there isn't exactly an error, and the Mythbusters support that.

See, as the Mythbusters say the energy is the same, but the two cars divide the damage between the two vehicles. However, they run the single car into an unbreakable steel wall, so all of the energy/damage is transfered solely to the car.

Savage Worlds says the damage is applied to both the vehicle and the stationary (not unbreakable but simply unmoving) object it hits. So if the Mythbusters had driven a car at 100 mph into another car, the effect would have been the same as the two cars hitting at 50 mph each.

So then to reflect the physics, if a vehicle without Heavy Armor hit a stationary object with Heavy Armor, then it would take 2d6 for every 5" of movement instead of 1d6 as the damage would all be applied against it instead of applied to both. Basically, the inverse of the soft obstacle rule.
Clint Black

Savage Worlds Core Rules Brand Manager



www.peginc.com


Return to “SW General Chat & Game Stories”

Who is online

Users browsing this forum: No registered users and 1 guest