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I have a war tank freezing in the air and one feather next to the tank, when I press the play I want the tank to reach the ground faster. Even when the weight differ they will reach the ground at the same time, so I want to put gravity to the tank and another gravity to the feather.

How can I do that?

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  • $\begingroup$ This is not a gravity problem (physically speaking): youtube.com/watch?v=E43-CfukEgs&feature=emb_logo (though, this does not answer what you ask) $\endgroup$ – lemon Oct 24 at 18:47
  • $\begingroup$ okay, that is great but I'm making a game that is in nature with air not in vacuum! $\endgroup$ – Muhammad Jeldeh Oct 24 at 19:13
  • $\begingroup$ A game would be great in a vacuum! $\endgroup$ – lemon Oct 24 at 19:20
  • $\begingroup$ Would this not be a simple solution? It's from an earlier version of Blender but the button/slider should still be there. - blender.stackexchange.com/questions/80929/… $\endgroup$ – Edgel3D Oct 26 at 8:00
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Fact that a tank reachs a ground faster than a feather falling from the same high is not a question of gravity, but matter of air friction. Thanks Lemon for pointing out :)


v01 Force Field - Drag

You can set Rigid Body as usual...

  • add Cube - enable Rigid Body simulation > Mass > 100 kg
  • add Plane - enable Rigid Body simulation > Mass > 0,6 kg

and simulate Air friction by adding Force field object (like Drag type) and play with Strength value. Here Linear 0.01

enter image description here

Notes

Example above is option how to slowdown falling object based on mass, without any physical accuracy, just to get desired effect.

For some reason speed fall is affected also by Dynamics > Damping Translation. Two objects, both of mass 1 kg, but one object with damping increased to 0.8 also gives air friction effect.


v02 Cloth Sim

Another option is to use cloth simulation, that has a parametr Air Viscosity per object, so it can be adjust individually.

enter image description here

In this example also Cube use Cloth sim, that with some setting can react as solid object. For tank you can just use Rigid Body as before.

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    $\begingroup$ And there was I, playing with 'Drag', and its 'Wind factor' which would seem logical.. but not much joy with profiles parallel to force plane.. although, strangely, it affects lighter objects more than heavy ones.. No useful documentation, yet, that I can find. Trial and error takes a long time. :( $\endgroup$ – Robin Betts Oct 24 at 20:44
  • $\begingroup$ Nice! ,, It would be lovely to get that falling-leaf swaying action going, naturally.. I guess it would take a full-blown fluid sim to do that? I'm not sure I've seen that done physically, anywhere.. $\endgroup$ – Robin Betts Oct 25 at 11:47
  • $\begingroup$ @RobinBetts Something like leafs could work with cloth and Turbulence force field I guess imgur.com/0oBHEpf (right now Im not sure why failed with plane ...) Yes I saw it somewhere ... $\endgroup$ – vklidu Oct 25 at 12:21
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You can simulate it using particles for instance.

enter image description here

Add two planes and scale their vertices to zero. Add a particle system to both and set normal speed to 0.

Set the particle amount to one:

enter image description here

For the feather, change the gravity setting to a lower value:

enter image description here

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