     color = '#0000a0'
     @context.fillStyle = color
     @context.beginPath()
-    @context.arc x, y,  10 , 0, Math.PI*2, true
+    @context.arc x, y,  15 , 0, Math.PI*2, true
     @context.closePath()
     @context.fill()
 

    @calculate_projection()

  calculate_initial_position: ->
    radian = @angle*Math.PI/180
    @dx = @force/Math.cos(radian)
    @dy = @force/Math.sin(radian)

  calculate_projection:() ->
    @projection_x += @dx
    @dy -= @g
    @projection_y += @dy

  image:() ->

    @projection_y = 0
    @g = 9.8
    @calculate_initial_position()
    @start_time = 0

  x: ->
    @initx + @projection_x
