1. Tilt your phone/device to move the floating cog.
The clue is on the bottom left. It says that 12 and 5 should move clockwise (to the right). Then it points to 7, which has an arrow that shows it should move counter-clockwise (to the left).
You have to hit XII, V, and VII and make them spin correctly. Hit them again to stop them from spinning and hit it in the right spot to make it spin in the right direction.
First make the cog hit the XII so it spins clockwise.
Next make the cog hit the V so it spins clockwise.
Finally make the cog hit the VII so it spins counter-clockwise.
2. Press the middle of the clock area to open the door.