# BlastPressure to Velocity Calculation/Explosion Behaviour

Hi there! I’m currently trying to reverse-engineer how explosion forces are calculated (I plan to draw paths of their explosions) and I’ve stumbled upon something odd. Maybe I’m overthinking this, but I’m trying to calculate the explosion velocity from a given BlastPressure at a certain position.
However, from reading documentation, it says that BlastPressure only describes the force/acceleration of the explosion. An instant force of 0 time results in no velocity change. Do explosions apply this force over a certain amount of time? And if so, what is this time?

Thank you.

Yep. The documentation is wrong. There is no force given (assuming t is zero, because roblox explosions are instanteous), just pure velocity.
Velocity and blast pressure are proportional, and mass and velocity are inversely proportional. It isn’t that much harder to get an equation from it.
v ∝ p
v ∝ 1/m
v = ( direction * p )/m/k

``````local predictedVelocity = ( part.Position - explosion.Position ).Unit * explosion.BlastPressure / part.Mass / 6080
``````

I found `k` after doing experiments with roblox explosions. But, I have no clue why this constant is here.
But that’s alright, that is the behaviour I was looking for.

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