GE Physics and gravity

Hi all
I am new on GE and I am making a simple swing where I have one arm that I am rotating by keyboard actuators along Y axis and a seat (children of arm) that should move affected by gravity during rotation of arm.but I don’t know how handle gravity for seat.How can I do this?How do I must setup logic?

Don’t use logic bricks, set everything to Rigid Body and join them with Rigid Body Joints. Gravity is taken care of by the BGE.

Great, the gravity is working now!
Is possible to handle the gravity and make rotate the seat only on his local Y axis and to block seat location axis? Because now the seat goes/fly off the arm while I am rotating arm…It is not linked correctly to the base of arm
Thank you very much for the help

Is the seat connected to the end of the arm, or the beginning? Check by selecting “show” in the hinge properties.