2秒後に自由落下.cs

    void Update()
    {
        intervalTime += Time.deltaTime;

        // マウス入力で左クリックをした瞬間
        if (Input.GetMouseButtonDown(0))
        {
            if (intervalTime >= 3.0f)
            {
                StartCoroutine(CreatePrefabCoroutine());
                intervalTime = 0.0f;
            }
        } 
    }
       
    IEnumerator CreatePrefabCoroutine()
    {
        var clickPosition = Input.mousePosition;
        clickPosition.z = 10f;
        var obj = (GameObject)Instantiate(Prefab, Camera.main.ScreenToWorldPoint(clickPosition), Prefab.transform.rotation);
        obj.GetComponent<Rigidbody>().constraints = RigidbodyConstraints.FreezeAll;
        //2秒待つ
        yield return new WaitForSeconds(2);
        obj.GetComponent<Rigidbody>().constraints = RigidbodyConstraints.None;
    }