RigidBody3D acceleration calculation

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Godot Version

4.2.1

Question

Hi, through trial and error, I’ve discovered that both Godot physics and Jolt plugin calculate the inertial force on a RigidBody3D as (pos - pos_last)/delta^2 * mass. My question is why? This doesn’t seem like a proper way to approximate a second derivative of position. Is this the norm in physics engines? Shouldn’t it be documented somewhere?

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Isn’t it a normal way to calculate force?
Or does the problem lies in calculation approximating acceleration by just using double delta?
(I am not that knowledgeable on physics engines myself)

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Thanks for replying. Yeah, the acceeration formula seems weird. Full disclosure my math is terrible.

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Actually, dont we already have velocity in PhysicsBodies? It would be easier to use delta velocity instead of delta position. I wish i would be better at reading source code to see how its implemented

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There is a velocity in a PhysicsBody and I’m using it. I ran into this trying to calculate a force that would counter bodys current inertia, thus keeping it in place ( tire grip ). The velocity property on a PhysicsBody roughly corresponds to (global_position - global_position_last)/delta ( I need to figure out how that is done in engine ), however, the PhysicsBody is only kept in place by a force of -linear_velocity/delta * mass (as I say in the original post ).