// 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

class example(MonoBehaviour):

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