Tinker always returning not found in eval() Laravel 5.1 -

i have models place in app/models, , if attempt run in tinker:

$user = new app\user; or $user = new app\models\user; 

i shown with:

class x not found in eval()'d code on line 1 

i found out following not work either:

$user = new user(); 

what doing wrong here?