Simple Machines is an app by Tinybop (previously) that uses simple machines–like the name implies–to demonstrate various elements of physics. Simple Machines, which features art by Jason Gilleard, is currently available on iOS.
Destroy a castle with a lever — but beware of the dragon! Make music in a pinball arcade with inclined planes. Send satellites into orbit with a set of pulleys. Lift sloshing fish tanks with screws. Travel through a wondrous world with a wheel and axle. Split an iceberg of mirrors with a wedge.
images via Simple Machines