Projectile

 public class Projectile : MonoBehaviour
    {
        [SerializeField] private Rigidbody _rigidbody;
        [SerializeField] private float _speed = 100;
        [SerializeField] private float _lifeTime = 10f;

        private Vector3 _direction;

        public Action<GameObject> TargetDetected;

        private void Awake() =>
            Destroy(gameObject, _lifeTime); // Лучше использовать пул объектов

        public void Throw(Vector3 direction) =>
            _direction = direction;

        public void Stop() =>
            _direction = Vector3.zero;

        private void FixedUpdate() =>
            _rigidbody.velocity = _direction * _speed;

        private void OnCollisionEnter(Collision collision)
        {
            TargetDetected?.Invoke(collision.gameObject);
            Destroy(gameObject);
        }
    }