RaycastHit.rigidbody

Description

The Rigidbody of the collider that was hit. If the collider is not attached to a rigidbody then it is null.

// Apply a force to a clicked rigidbody object.

// The force applied to an object when hit.
var hitForce: float;

function Update() {
    if (Input.GetMouseButtonDown(0)) {
        var hit: RaycastHit;
        var ray = Camera.main.ScreenPointToRay(Input.mousePosition);

        if (Physics.Raycast(ray, hit)) {
            if (hit.rigidbody != null)
                hit.rigidbody.AddForce(ray.direction * hitForce);
        }
    }
}

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public float hitForce;
    void Update() {
        if (Input.GetMouseButtonDown(0)) {
            RaycastHit hit;
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            if (Physics.Raycast(ray, out hit))
                if (hit.rigidbody != null)
                    hit.rigidbody.AddForce(ray.direction * hitForce);
                
            
        }
    }
}

See Also: Physics.Raycast, Physics.Linecast, Physics.RaycastAll.