Explosion2D.cs

using UnityEngine;
using System.Collections;

public class Explosion2D : MonoBehaviour {
	public float power = 10;
	public float radius = 10;

	void OnMouseDown() {
		Explode (transform.position, radius, power);
	}

	public static void Explode(Vector3 sourcePos, float radius, float power) {
		var objs = Physics2D.OverlapCircleAll (sourcePos, radius);

		foreach (var obj in objs) {
			var body = obj.GetComponent<Rigidbody2D> ();
			if (body != null) {
				AddForce(body, sourcePos, power);
			}
		}
	}
	
	public static void AddForce(Rigidbody2D body, Vector3 sourcePos, float power) {
		var f = body.transform.position - sourcePos;
		f.Normalize ();
		f *= power;

		body.AddForce (f, ForceMode2D.Impulse);
	}
}