Kicking Technique vs a Standing Broom vs Snap Weapon technique

[Plane]

I think I could possibly snap a light/weak broom in half using my hands. According to the Snap Weapon technique in GURPS Martial Arts, you can do Thrust Crushing damage to accomplish this.

The kicking technique ALSO does thrust crushing...

But let's say I encounter a broom which is standing up like in https://www.youtube.com/watch?v=p5mzpUrl91Y&t=1m

I'm pretty sure if I kicked that broom I would not be able to snap it in half - it would probably take minimal damage and just suffer knockback/knockdown as if I had done a Shove or Push Kick on it.

I'm not really sure how to describe this attribute of lighter objects. Should there possibly be some sort of reduction on how much crushing damage a low-HP object can take by big hits that would inflict a lot of knockback on them?

I almost think (despite punches doing less damage than kicks) that I'd be more likely to snap a standing broom in half using an arm strike than with a leg strike, simply because the punch hits faster than the kick does.

Kicks might have more force (higher mass in the mass x acceleration formula) than punches, but this is a situation where I think acceleration would somehow be more important.

I don't know the physics terms as to why though.

Obviously a kick would have a lot more force if the broom were braces against a wall (or held in someone's hand as a weapon) because then it can't get knocked back to diminish the force of the hit...

I guess I'm wondering at what sort of damage formulas we're looking at here to distinguish why a Snap Weapon would succeed where a Kick Attack would fail.

[Farmer]

Being able to break an object like that requires you achieve a sufficient shear force. That seems extremely unlikely with a realistic strike by an unarmed human. I'm not about to attempt the maths involved because it's complex, I'm not an engineer, and so I wouldn't know if I was getting it right or not.

I'm not sure there's a game mechanic for accurately determining when you would knock/push rather than damage. I think a GM just applies a common sense (as may apply within a given game world) or considers the story/plot ramifications and decides.

Not everything can be, nor needs to be, reflected in a formula.

[Gollum]

If you want to be simple, you can just use an attack roll and decide that if it is successful, the broom will be projected in the room and, if the margin of success is high (something like 5+ or critical success), it will also be broken.

If you want to be more realistic you can use the damage to object rules (Basic Set, page 483). A broom is something like a pole. A good wooden pole (1” thick) has DR 1, HP 14 (Basic Set, page 558). But a mere modern broom is surely not so solid. Probably something like DR 1 (if any), HP 5 …

The attack will be an All-Out Attack Strong (+2 to damage), Telegraphic (+4) with several turns of Evaluate (+3) …

A good karateka (ST 11, Karate DX+1 or better) will inflict 1d cr damage with a kick which means 1d+2 with the All Out Strong attack (3 to 8, average 5.5). Then, if the broom is reduced to 0 HP or less, you will have to roll against his HT (probably 10) to see whether it breaks.

But the broom must be firmly fixed on the ground or, it will be projected through the room rather than breaking … Unless being very lucky … That is, unless the player scored a critical success. In my humble opinion, there is no realistic way to break a broom which is not firmly fixed (or firmly held in hand by someone) with a crushing attack.

[Farmer]

Originally Posted by Gollum

In my humble opinion, there is no realistic way to break a broom which is not firmly fixed (or firmly held in hand by someone) with a crushing attack.

Yeah, the shear force has the rate of change in momentum to break it before it moves it. That's not happening from a realistic human strike. A bullet could do it, if it hit on just the right angle, maybe a very sharp sword swung extremely hard and just right - maybe.

[Plane]

Originally Posted by Farmer

Yeah, the shear force has the rate of change in momentum to break it before it moves it. That's not happening from a realistic human strike. A bullet could do it, if it hit on just the right angle, maybe a very sharp sword swung extremely hard and just right - maybe.

I'm wracking brain trying to think of stat-wise how to represent this.

It almost seems like a Roll With Blow technique (double knockback half damage) except that doesn't really make sense for a DX 0 inanimate object.

Like I'm assuming you can't use stuff like RWB to lower damage if you can't actually move away from your foe, like if they have you grappled.

Maybe for light pliable objects we can have some kind of technique perk where it's RWB based on HT instead of DX and it doesn't require awareness of attacks?

RWB seems like it's already a free action (almost like an active defense except pretty sure you can still do it after a failed defense) so this would almost be like improvined Reduced Time +20% to Reflexive +40% except I don't know what baseline advantage I'd be changing it to.

The cinematic technique which it seems like all sentient lifeforms would have access to seems to work something like this:

Injury Tolerance: Damage Reduction (Cosmic: divides Basic Damage not Penetrating +50%; Crushing Only -40%; Requires DX skill roll -10%) [50]

except there's differences I can't stat like:

1) the doubling of the knockback as a cost (occasional benefit) for attempts (even failed ones)
2) that there is no FP cost to retry after failures
3) critical success reducing basic damage to 1
4) knockdown and stun on crit fail
5) the -2 penalty to the DX/combat roll (hard to use is -3 per -5%)

There's also the issue that RWB defaults to ANY combat skill (or acrobatics) and when using requires skill roll, the limitation is a 5% lower discount per PU8p17 if the skill is Easy (like Brawling).

[Farmer]

Originally Posted by Plane

I'm wracking brain trying to think of stat-wise how to represent this.

You can't. GURPS isn't granular enough, nor suited to the complex and highly variable maths involved. It's done by GM fiat. The closest you get is Breaking Blow, but that specifically requires the object to be braced.

So, again, it just comes down to GM fiat, which can be as realistic or not as the GM prefers.