how to make it so that the rigid body object does not fall code example

Example 1: way do we use a Rigidbody in Get.component();

using UnityEngine; using System.Collections;  public class Test : MonoBehaviour {     private Rigidbody rb;     void Awake(){          rb = gameObject.GetComponent<Rigidbody>();     }       private void Example() {         rb.velocity = some value;     } }

Example 2: unity rigidbody

private Rigidbody rigidbody