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?
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 :)
You can set Rigid Body as usual...
and simulate Air friction by adding Force field object (like Drag type) and play with Strength value. Here Linear 0.01
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.
Another option is to use cloth simulation, that has a parametr Air Viscosity per object, so it can be adjust individually.
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.
You can simulate it using particles for instance.
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:
For the feather, change the gravity setting to a lower value:
