If you've yet to play Angry Birds, I'm willing to bet you've at least glimpsed its icon floating on the App Store's charts. For good reason, too; it's an addictive game. The basic formula is a bunch of angry birds, a slingshot, and the egg-stealing pigs and their castles. The goal of this little physics game is to demolish each and every one of the aforementioned castles—but does Angry Birds actually follow the rules of physics?
Apparently one of Wired's writers, Rhet Allain, just couldn't stop thinking about the posibilities:
But what about the physics? Do the birds have a constant vertical acceleration? Do they have constant horizontal velocity? Let’s find out, shall we? Oh, why would I do this? Why can’t I just play the dumb game and move on. That is not how I roll. I will analyze this, and you can’t stop me.
Long story short: he took one of the developer's walkthrough videos and decided to analyze it using a program called Tracker Video Analysis. He used the program to determine path of the bird's flight, and then used that data to graph the bird's horizontal and vertical movement separately. (In projectile motion, you typically separate horizontal and vertical components.)
His discovery? Angry Birds considers only the force of gravity on the bird—once you fire the bird from the slingshot; the app doesn't calculate air resistance or anything like that. And assuming that gravity in Angry Birds is equal to Earth's gravity, the slingshot is five feet tall and the red bird is a little over two feet. Jeez...talk about a large bird!
The physics that Mr. Allain used actually felt quite familiar—since I essentially had to do the same thing in a physics lab last week. Bounce a golf ball, take a video, then measure its path with a computer and use projectile motion equations -- he only difference was that we were trying to determine gravity, whereas he assumed gravity was -9.8 meters per second and instead tried to determine the size of different Angry Birds elements. Of course, the other difference between Angry Birds and my physics lab was that, you know, Angry Birds is artificial, and thus the equations that Wired derived worked a lot better than our sad attempts.
So, if you were desperately wondering—the Angry Birds slingshot is more than twice your height and the birds themselves are giant and vicious. Now I'd like to see him calculate the height of those pig castles.