공식 링크 : https://docs.unity3d.com/6000.0/Documentation/Manual/2d-physics/effectors/surface-effector-2d-reference.html
접촉하는 Rigidbody2D 객체에 힘을 자동으로 주는 표면용 Effector야.
쉽게 말해,
GameObject > 2D Object > Sprite
Box Collider 2D
Surface Effector 2D
Effector
Used by Effector