Lifting of Plate

If this is homework then you should be doing your own homework.

If this is for a job then you need to consult with someone qualified to do this. You are in way over your qualifications and we don't want to help you get someone hurt or killed.

Shouting doesn't improve the lack of clarity.

Get a pencil and a piece of paper and draw it to scale. Then SELECT the proper cylinder from a vendor catalog.

If you can't even figure the length of the cylinder, what makes you think you could ever design one?

I think not.

Come on, mate, give us (and yourself) a break. Which edge is the hinge? Where is the rod connected to the plate? Where is the cylinder fixed?

Oh, by the way - without constrains, the minimum stoke is something less than 1mm - but you'd need a very large bore cylinder and lots of pressure. _{This answer is as useless as your question.}

What does "180 degree[s] from horizontal" mean--upside down?

To design a pneumatic cylinder, you can start by putting a piston inside a tube...and then add various details.