# Going ragdoll after a physics hit - what is the correct impulse value?

I am trying to do the following - after being hit by a simulated physical object, a non-simulated character starts simulating physics if the hit was strong enough and reacts appropiately. By “appropiately” I mean: close to what the reaction would be if the character was already ragdolling before the impact and simply reacted physically.

My problem here is how to get a proper hit impulse. The hit that causes the transition is against a non-simulated character, so just ragdolling in response means no hit reaction and I need to apply an impulse on my own. What’s the right impulse? I tried using -1*normal impulse of the hit, or multiplying the physical objects’ pre-hit velocity and mass.

Either gives me a working, but odd result: the impulse has a direction that seems ok, but it’s way too strong and I need to multiply it by a factor smaller than 1 (somewhere around 0.2-0.3) to get an expected reaction. Any ideas on what’s happening here and why? In particular, where does the specific factor come from and how would I calculate it without blind testing.