[Rq-rules] Re: Knockback and falling damage.

[Simon Phipp]

Brad Furst:
  
> Yes, it's square with respect to time, but we don't use time as a 
> measure for falling in gaming.
>
> It's linear, with respect to distance, which is how we measure falls 
> in gaming.
> :-)

  Anything that uses equations of motion to work out RQ damage is a bit complicated and probably too realistic.
   
  > Terminal velocity occurs falling from about 280 feet. More distance 
> than that is negligible to damage.

  Soltak Stormspear (from whence came the soltakss in my email address) had a cloak made of shadowcat fur that enabled him to completely ignore the effects of wind passing over him - the cloak would billow around him but he would be unaffected. It also meant that he ignored terminal velocity and could fall very, very quickly.
  
Tom Cantine:

> However, it seems to me that knockback distance is a linear 
> function of velocity, not of kinetic energy (which is proportional 
> to the square of velocity). To fling someone 60m would require a 
> minimum velocity of about 45 m/s, which is about the speed one 
> would attain after falling about 100 m. So damage on landing should 
> be about 33d6.

  Strictly speaking, it should be based on momentum, which is dependent on both velocity and mass, the bigger you are the harder you hit.
   
  The following illustrates perfectly why RQ abstracts things into easy to use tables.
   
  With the above caveat of "Anything that uses equations of motion to work out RQ damage is a bit complicated and probably too realistic", we have:
   
  Disregarding air resistance as negligible, the only force stopping you from moving in a straight line is gravity pulling you down, so the distance travelled depends on how far up you are hit.
   
  So, using s=ut+1/2at^2 for downward movement, with u=0 (initial downward velocity = 0), a=10 (approx), we have
  s=0+5t^2
  t=sqrt(s/5)
  Using v = d/t for horizontal distance, v=velocity, t=time, we substitute for t and get
  d=v * sqrt (s/5)
  For someone knocked flat on their centre of gravity, so they fall 1m, d=v*sqrt(1/5), d=0.44v (approx).
  For someone knocked a bit higher, so they fall 2m, d=0.6v (approx).
   
  Are you still with me, or have your eyes glazed over yet?
   
  So, if you fling someone at a velocity of 45m/s, then they only move approx 20m in a flat whack but they move 27m on a slightly arced whack. 
  To fling someone 60m, using v=d/0.44 gives a velocity of 136 m/s, using v=d/0.6 gives 100m/s.
   
  Of course, hitting someone while they are standing on a hill does change the values slightly as the vertical distance changes. As does the angle of projection, so a giant hitting you with an upward swing would potentially knock you further than with a straight poke to the ribs, depdning on the angle concerned.
   
  According to the maths, the horizontal component of the momentum doesn't actually change, so you should take the same damage if you hit a wall straight away as if you hit a wall just before you hit the ground. But where's the fun in that? The vertical component is merely falling damage, so if you fall 1m you get a bumped head, so it's best to ignore that.
   
  Now, the problem comes when working out how much damage is done for a certain velocity. The easiest way of doing this is to work out the velocities achieved at each falling distance, using the falling damage chart, then using the same damages for calculated velocities. So, a giant hits you and knocks you 60 metres, we know from above that this equates to a velocity of between 100 and 136 m/s, so we cross reference our falling distance/velocity/damage table to see how much damage that equates to. Simple.
   
  Except, however, that damage depends on mass as well as velocity, so you have to take into account the SIZ of the person flung. So, you need a distance/damage/velocity/momentum chart and read the values off that.
   
  See how fun using physics can be when misapplied?
   
  Do you think you can draw up the tables to make the calculations easier? :-)
   
  > I don't think that damage should max out at 12d6, because the 
> entire body is hitting a solid surface, and while 12d6 is every bit 
> as lethal as 33d6, the degree of overkill is a useful indication of 
> how recognizable the residue will be.

  12D6 is only lethal if you haven't got lots of hit points and armour. But, yes, it shouldn't max out at any realistic number.
   
  See Ya
   
  Simon
  
 
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