Instantiate rigidbody C#

Questions & Answers
1

There is an example from Unity Scripting:

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {

    public Rigidbody projectile;
    void Update() {
        if (Input.GetButtonDown("Fire1")) {
            Rigidbody clone;
            clone = Instantiate(projectile, transform.position, transform.rotation);
            clone.velocity = transform.TransformDirection(Vector3.forward * 10);
        }
    }
}

and that’s my code:

using UnityEngine;
using System.Collections;

public class Shoot : MonoBehaviour {
    public double Speed = 3.0;
    public Rigidbody grenadePrefab;
    	void Start () {
	
	}
	
	void Update () {
        if (Input.GetButtonDown("Fire1"))
        {
        
            if (Collisions.GRENADE_AMMO > 0)
            {
                Rigidbody grenade = (Rigidbody)Instantiate(grenadePrefab, transform.position, Quaternion.identity);
                grenade.rigidbody.AddForce(Vector3.up * 2000, ForceMode.Impulse);
                Collisions.GRENADE_AMMO -=1;
                print(Collisions.GRENADE_AMMO);
            }
        }
	
	}
}

When using the example, it says, it needs a cast
But after adding a cast in both cases occures an error

InvalidCastException: Cannot cast from source type to destination type.
Shoot.Update () (at Assets/Scripts/Shoot.cs:19)

Can anyone please tell me, what the problem is?

2

The code seems to instantiating the Rigibody rather than the GameObject containing it. I think it should be:

var clone = Instantiate(projectile.gameObject, ...);
clone.rigidbody.velocity = ...

Your version is actually half doing that already.