Yes you can, it becomes much simpler to do physics when it's just in a line like that.
The motion is simple: increase the speed with gravity and move down with the speed.
Collision detection is done by looping over the blocks from the bottom up. If the current block overlaps the block below push it up and set it's speed to the speed of the block below ...and repeat.
https://dl.dropboxusercontent.com/u/542 ... olumn.capx
ps. the speed change isn't physically correct when the objects collide. The actual speed of both blocks after a collision should be the average of the speeds, but it would add some complexity to the events.