How do you open the door on level 10 on 100 exits on the iPad?
Press and hold the home button in the game (the one that turns green). While holding it, press the home button on your device. The game will exit but when you come back the door will be open. See related link for screenshots.
Tilt your device so the can moves in front of the door. Then tilt your device toward you so the can moves closer to you (until it stops moving). Finally tilt your device away from you so the can slides into the door, breaking it. Move the can and go to the next level. See related link for screenshots.