Rotate object under gravity force - ios

Question

I'm trying to create a scenario where there's a radial gravity field. In this scene, there's also an object built by two physics bodies with a different mass.
When I run this code, the radial gravity field is created correctly and the body goes to gravityCenter.
I'm expecting that the body rotates too because the head is heavier than the tail but this doesn't happend.
Why?
class GameScene: SKScene {
let object = SKSpriteNode(imageNamed: "myobj")
let myCategory : UInt32 = 0x1 << 0
override func didMove(to view: SKView) {
self.physicsWorld.gravity = CGVector(dx: 0, dy: 0)
let gravityCenter = SKFieldNode.radialGravityField()
gravityCenter.isEnabled = true
gravityCenter.position = CGPoint(x: size.width, y: size.height * 0.5)
gravityCenter.strength = 0.5
addChild(gravityCenter)
object.position = CGPoint(x: size.width * 0.1, y: size.height * 0.9)
object.scale(to: CGSize(width: 100, height: 25))
let head = SKPhysicsBody(circleOfRadius: object.size.width/5, center: CGPoint(x: object.size.width/2, y: 0))
let tail = SKPhysicsBody(circleOfRadius: object.size.width/50, center: CGPoint(x: -object.size.width/2, y: 0))
head.mass = 500
head.categoryBitMask = myCategory
head.allowsRotation = true
head.isDynamic = true
head.angularDamping = 0
head.affectedByGravity = true
tail.mass = 2
tail.categoryBitMask = myCategory
tail.allowsRotation = true
tail.isDynamic = true
tail.angularDamping = 0
tail.affectedByGravity = true
object.physicsBody = SKPhysicsBody(bodies: [head, tail])
object.physicsBody?.categoryBitMask = myCategory
object.physicsBody?.allowsRotation = true
object.physicsBody?.isDynamic = true
object.physicsBody?.angularDamping = 0
object.physicsBody?.affectedByGravity = true
addChild(object)
}
}

Answer 1

Well, from a physics standpoint SpriteKit is behaving correctly. If you think about it, more mass does mean more gravitational force, but it also means more inertia, which exactly cancels out the increased force. Perhaps introduce a little bit of linearDamping into the tail? That would get the body to rotate by making the head drag the tail a little bit.