The torque applied to the rigidbody every frame.

	// Rotates the object around the world y-axis
	constantForce.torque = Vector3.up * 2;

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void Example() {
        constantForce.torque = Vector3.up * 2;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def Example() as void:
		constantForce.torque = (Vector3.up * 2)