unity assign rigidbody to gameobject code example

Example 1: how to add reference to rigidbody 2d

public Rigidbody2D rb;

Example 2: unity how to set rigidbody velocity

Vector3 velocity = new Vector3(10f/*x*/, 10f/*y*/, 10f/*z*/);
GetComponent<Rigidbody>().velocity = velocity;