Proving the Motion of Point P: Vertical or Elliptical?

[nohkie]

https://www.physicsforums.com/attachment.php?attachmentid=56184&d=1362060936

https://www.physicsforums.com/attachment.php?attachmentid=56185&d=1362060998

https://www.physicsforums.com/attachment.php?attachmentid=56186&d=1362061038
Any help of how to prove this problem would be appreciated, I am just not understanding the question and can't see whether or not there is vertical motion on point p or if the motion because elliptical? If anyone could prove this would be greatly appreciated. (I don't know how basic this is to people, I'm only in my high school and my teacher didn't get a chance to explain anything about it. It's driving me crazy.)

 

[voko]

You could start by doing the FBD for P.