As we already know, we need to get a reference to the rigidbody component so we can use it in the FixedUpdate() function to move the bullet. As such, let's declare another variable:

// [...] 
public class BulletController : MonoBehaviour { 
 
    public float speed = 10.0f; 
 
    public float timeBeforeDestruction = 10.0f; 
 
    private Rigidbody2D rigidBody; 
 
   // [...] 
} 

The Start() function is always a perfect place to initialize references to other components, so we can just write:

    void Start() { 
        rigidBody = GetComponent<Rigidbody2D>(); 
    } 

As a result, we are now able to use the rigidbody of the bullet.