knockback vs trees
 

How does it work? Trees get ST + x vs knockback where x = ground ST?

Re: knockback vs trees
 

In general, trees are firmly attached to the ground, and won't suffer "knockback" unless they are uprooted or shattered - ie, sustain enough damage to the roots or trunk to destroy them.

Re: knockback vs trees
 

I'd say that a tree would get its' ST vs KB, and immediately take collision damage as it is already anchored in a solid surface. You'd have to break the tree (or the ground!) prior to it suffering any other effects from KB.

By RAW, I'm not sure. I don't believe a tree would get any benefit from being anchored in the ground; though I admit I could be wrong.

Re: knockback vs trees
 

Just keep in mind that a tree's strength and hit points are going to be on a scale that GURPS isn't meant to deal with. If you're going to try to deal knockback level damage to a tree, you're going to need something the size of a semi truck, moving at great speed.

But nothing hits a tree hard enough to cause knockback and walks away from it. The aforementioned semi truck will be headed to the scrap yard for anything bigger than a sapling. A full grown oak, the truck is the one gonna be taking the knockback.

Unless you're dealing with godlike super heroes, this is best handled by narrative rather than RAW. And at that point you might be using the wrong system.

Re: knockback vs trees
 

If your running into the tree I would call it a collision.
If your trying to uproot the tree, or otherwise just do KNB I would add the trees ST plus the weight of each hex of ground its roots occupy.

EDIT: And Clay is right in that most of the time in a Non Supers setting this would be more of a narrative thing and not worth the effort to figure out.
However to allow for Supers, Uber Fantasy or HT (does an explosion do enough KNB for example) I tossed in my ideas.

Re: knockback vs trees
 

BLASPHEMY!!!

When I do rules light, I use RISUS.

Re: knockback vs trees
 

The tree's root system makes it count as a braced object, much as Breaking Blow can be non-cinematically used against things like boards. If you wish to use the extra detail, treat the tree as having suffered knockback but immediately collided with a solid object -- the ground its root system is clinging to -- doing, and suffering, additional collision damage. If the "collision" damage is sufficient to destroy the ground in which the tree is rooted, it breaks: the tree comes free.

To handwave it, give a small damage bonus for the damage done to the tree -- hitting unmoving, planted things is easier. Treat the damage bonus as also being done to the ground touching the tree, and when you figure the ground has suffered enough damage, the tree is uprooted.

Re: knockback vs trees
 

An intact tree is best characterized as No Legs (Stationary). I believe that includes immunity to knockback.

Re: knockback vs trees
 

My Netherlander friend who used to drive a Leopard II MBT disagrees. :-)

Re: knockback vs trees
 

Is that knockback or knockdown?