understanding scrollTop

understanding scrollTop

Hey guys, 

Just a small difficulty in how scrollTop works , 

I have the following HTML and css code :

  1. <body>

  3. </body>

CSS : 

  1. body{
  2. height: 4000px;
  3. background: #eee;
  4. }

Jquery code : 

  1. $( "html" ).scrollTop(5000);
now if i say : 

  1. $( "body" ).scrollTop(5000);

scrollTop does't work .. Why ?? 

my difficulty is also listed in the fiddle :  Fiddle