This might be a silly question for some but I was wondering how do I size a DC motor to move a weight and counter weight? Suggestions for a better design are also welcome. I want to build an enclosure with an automatic door (simple limit switches and an arduino to flip the motor on and off). But lifting the door seemed like it would take a large motor since the door is most likely going to be plywood and several feet x several feet. So I thought why not counterweight it to ease the load on the motor. But its been a long long time since I took physics so I don't really know how to find what size motor I will need. Or if there is anythign I'm forgetting to take into account here. So I thought I'd ask you guys. I'm attaching a picture of what I had in mind in case my explanation wasn't great. Thanks in advance.