First place your object on the bottom of the screen:
object.y = (display.contentHeight + display.screenOriginY * -2) + object.contentHeight * 0.5
//if starting outside of the screen
object.y = (display.contentHeight + display.screenOriginY * -2) - object.contentHeight * 0.5
//if starting at the bottom of the screen
then perform transition.to
transition.to(object, { time = 500, y = 0 - display.screenOriginY })
I wrote it from my memory, so it may not work by copy + paste, but idea stays the same.
object - this is your object you want to transform
display.screenOriginY - this is the distance from the top of the actual screen to the top of the content area (more info here: https://docs.coronalabs.com/api/library/display/screenOriginY.html )
You may also need to read about transitions: http://docs.coronalabs.com/api/library/transition/to.html