GameDevTVObstacleDodge/Assets/Scripts/Dropper.cs

using UnityEngine;

public class Dropper : MonoBehaviour
{
    [SerializeField] float timeToWait = 3f;
    Rigidbody rb;
    MeshRenderer meshRenderer;
    // Start is called once before the first execution of Update after the MonoBehaviour is created
    void Start()
    {
        rb = GetComponent<Rigidbody>();
        meshRenderer = GetComponent<MeshRenderer>();
        rb.useGravity = false;
        meshRenderer.enabled = false;
    }

    // Update is called once per frame
    void Update()
    {
        if (Time.time > timeToWait)
        {
            rb.useGravity = true;
            meshRenderer.enabled = true;
            Destroy(this);
        }
    }
}