# How can I measure a particles change in position per frame?

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Rapid changes in direction or position is a characteristic of turbulent flow. I am currently reading particles into VOPs via point clouds, and I am unsure how to measure the change from the previous frame's position. I want to do it this way even though I could get similar results using acceleration. That wont do me any good if a particle comes to a screeching halt though.

Thanks!

Jason

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as far as i know velocity is the change of position from frame to frame .. so probably the thing you are really looking for is acceleration if lenght(velocity) > 0 ?

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actually, I am looking for acceleration... It must be 4am! Hehe, thank you. Nice stuff by the way!

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Ok so I have another question now...

If I use a force where y=-10, my particles acceleration is -10 constantly. If acceleration is the change in velocity per frame, wouldn't this be different? Or am I missing something?

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Acceleration is the first derivative of velocity with respect to time: the rate of change of velocity. So, acceleration = difference_in_speed/difference_in_time. If you want that to be precise you can take the limit of it as difference_time -> 0, so differentiate if you know the function. That is unlikely however so you could just calculate a rough value based on 1 frame as your time difference.

Edited by Macha

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Acceleration is the change in velocity over a period of time (usually 1 second). From physics, the sum of all forces = mass * acceleration ( F = ma). If your force is -10 and your mass is 1, your acceleration will always been -10 in y. Starting with an initial velocity of 0, after 24 frames of ay=-10, Vy = -10.

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Thank you both for the physics lesson.

I guess my question now is: how can I grab the velocity of something from a previous frame in pops so that I can use it to find the acceleration?

If I understand correctly, I can use vel2 - vel1 divided by the time increment to get the acceleration.

Edited by mightcouldb1

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is that what You want?

veldif.zip

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is that what You want?

I never thought about using nodes to store attributes the way you did. Thank you! Perfect solution.

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