I heard that most of a rocket's power is used to get out of the atmosphere. So I was wondering if it would it work to send a very low powered rocket (maybe even something that was simply shot using compressed air) up ~50 km to the edge of the atmosphere (on the high altitude balloon) to be launched there? Would something like that be able to get into orbit? Or even go to the moon?
I know next-to-nothing about rockets, so I hope this doesn't sound like a dumb question :)