<Canvas x:Name="root" 
  xmlns="http://schemas.microsoft.com/client/2007"  
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Width="270" Height="70">

  <Rectangle x:Name="rect" Canvas.Top="10" Canvas.Left="10" Width="50" Height="50" Fill="royalblue">
    <Rectangle.Triggers>
      <EventTrigger  RoutedEvent="Rectangle.Loaded" >
       <BeginStoryboard>
        <Storyboard 
          BeginTime="0:0:1"
          FillBehavior="HoldEnd">
          <DoubleAnimation  
            Storyboard.TargetName="rect"
            Storyboard.TargetProperty="(Canvas.Left)"                                                                                                                     
            Duration="0:0:2"
            FillBehavior="Stop"
	    SpeedRatio="2"
            From="100" To="210" 
          />
        </Storyboard>
       </BeginStoryboard>
     </EventTrigger>
    </Rectangle.Triggers>
  </Rectangle>
</Canvas>

