var GravityObject = Class.create();
	
	GravityObject.prototype = {
		
		objGravityExecutor: null,
		objGravityVector: null,
		objCallbackFunction: null,
		bActive: false,
		nDelay: 0.05,
				
		initialize: function(nX,nY,objFunction){
			this.objGravityVector = new DoublePair(nX,nY);
			this.objCallbackFunction = objFunction;
		},
		
		setVector: function(objVector){
			this.objGravityVector = objVector;
		},
		
		getVector: function(){
			return this.objGravityVector;
		},
						
		turnOff: function(){
			if(this.objGravityExecutor){
				this.objGravityExecutor.stop();
				delete this.objGravityExecutor;
				this.objGravityExecutor = null;
				this.bActive = false;
			}
		},
		
		turnOn: function(){
			if(!this.objGravityExecutor){
				this.objGravityExecutor = new PeriodicalExecuter(this.objCallbackFunction,this.nDelay);
				this.bActive = true;
			}
		},
		
		isActive: function(){
			return this.bActive;
		}
		
	};