Q about velocity/force and how those are calculated

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Hi all, noob question about particles and velocity/force, and how they are calculated.

I have an animation with 24 frames (1..25), with frame rate 24.

If i have a particle at position 0, 0, 0, and if i apply velocity 1, 1, 0 to it, particle position will be 1, 1, 0 at frame 25.

Now, if i add downward force 0, -1, 0 to it, i would expect that particle position at frame 25 is 1, 0.5, 0. But it's not - it's 1, 0.479167, 0..ish. Am i missing something here, or is this just some kind of rounding error.

If you look at the attached file, initial velocity is add via POP Wrangle (only at frame 1), in order to keep the point at pos 0, 0, 0 in frame 1. If i use Set initial velocity in POP Source, position will not be 1, 1, 0 at frame 24 (?!?!): initial velocity is add in frame 1, whereas velocity from wrangle is add after frame 1.

It doesn't seem to matter which method is used - when the downward force is applied, position is always a bit off. There is probably a very simple solution for this (there usually is) but i don't get it (as usual )

Cheers
-k

Attachments:
screenshot.png (202.4 KB)
particles.hipnc (241.3 KB)

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