CODE EXAMPLE FOR CSHARP

Rotating an object in Unity usign Physics

using UnityEngine;

public class rotation_example : MonoBehaviour
{
    public float torque;
    public Rigidbody rig;

    void Start()
    {
        rig = GetComponent<Rigidbody>();
    }

    void FixedUpdate()
    {
        rig.AddTorque(transform.up * torque);
    }
}