I've actually tested below and seems to be working?
$('.sc-bar').css('transform','scaleY(0.5)');
Is the line enclose on $(document).ready() or made sure that jQuery is loaded before using this like below?
// A $( document ).ready() block.
$(document).ready(function() {
// your code here...
$('.sc-bar').css('transform','scaleY(0.5)');
});