# Tag Archives: angry birds

## Flappy Bird Physics Is Real Life?

If you don’t already know, Flappy Bird is the hot new mobile game right now. The premise is simple: navigate the bird through the gaps between the green pipes. Tapping the screen gives a slight upward impulse to the bird. Stop tapping and the bird plummets to the ground. Timing and reflexes are the key to Flappy Bird success.

This game is HARD. It took me at least 10 minutes before I even made it past the first pair of pipes. And it’s not just me who finds the game difficult. Other folks have taken to Twitter to complain about Flappy Bird. They say the game is so difficult, that the physics must be WRONG.

So, is the physics unrealistic in Flappy Bird?

Sounds like a job for Logger Pro video analysis! I used my phone to take a video of Flappy Bird on my iPad. To keep the phone steady, I placed it on top of a ring stand with the iPad underneath.

(I’ve uploaded several of the videos here if you’d like to use them yourself or with students: Flappy Bird Videos.)

Then I imported the videos into Logger Pro and did a typical video analysis by tracking Flappy’s vertical position in the video. Sure enough, the upside-down parabolic curves indicate Flappy is undergoing downward acceleration.

But do the numerical values represent normal Earth-like gravity or insanely hard Jupiter gravity? In order to do this, we need to (1) set a scale in the video so that Logger Pro knows how big each pixel is in real life and (2) determine the slope of Flappy’s velocity-time graph while in free fall, which is equal to the gravitational acceleration.

The only thing we could realistically assume is the size of Flappy Bird. If we assume he’s as long as a robin (24 cm), then the slope of the velocity-time graph is 9.75 m/s/s, which is really close to Earth’s gravitational acceleration of 9.8 m/s/s. Flappy Bird is REAL LIFE.

So then why is everyone complaining that the game is unrealistic when, in fact, it is very realistic? I blame Angry Birds and lots of other video games. Repeating the same video analysis on Angry Birds and assuming the red bird is the size of a robin (24 cm), we get a gravitational acceleration of 2.5 m/s/s, which only 25% of Earth’s gravitational pull.

In order to make Angry Birds more fun to play, the programmers had to make the physics less realistic. People have gotten  used to it, and when a game like Flappy Bird comes along with realistic physics, people exclaim that it must be wrong. As one of my students notes:

UPDATE 31 Jan 2014:
Inspired by a tweet from John Burk,

we made a video showing Flappy Bird falling at the same rate as a basketball:

UPDATE 1 Feb 2014: While the gravitational acceleration in Flappy Bird is realistic, the impulse provided by the taps are NOT realistic. Here’s a velocity-time graph showing many taps. When a tap happens, the velocity graph rises upward:

As you can see, no matter what the pre-tap velocity (the velocity right before the graph rises up), the post-tap velocity is always the same (a bit more than 2 m/s on this scale). This means that the impulses are not constant. In real life, the taps should produce equal impulses, which means that we would see that the differences between pre- and post-tap velocities are constant.

TL;DR: Is the physics in Flappy Bird realistic? Yes AND no.
YES: The gravitational pull is constant, producing a constant downward acceleration of 9.8 m/s/s (if we scale the bird to the size of a robin).
NO: The impulse provided by each tap is variable in order to produce the same post-tap velocity. In real life, the impulse from each tap would be constant and produce the same change in velocity.

UPDATE 1 Feb 2014 (2): Fellow physics teacher Jared Keester did his own independent analysis and shares his findings in this video:

You are a game designer for Rovio Entertainment, the company that makes Angry Birds.  The human resources department wants your input. They are hiring several programmers to build the physics engine for Rovio’s newest game. Here are the demo videos from the top four applicants. Which applicant(s) would you recommend for hire?

Applicant A

Applicant B

Applicant C

Applicant D

Download the original video files for analysis in Logger Pro or Tracker.

These videos were not created by me. I found them online several years ago, but I can’t remember where. If anyone knows, please tell me so I can give the creator proper credit. Thanks!

## My TEDxNYED Session: Learning Science by Doing Science

Many thanks to the TEDxNYED 2012 crew, especially True Life Media, Basil Kolani, Karen Blumberg, and Matthew Moran for an awesome event. Be sure to check out the rest of the TEDxNYED 2012 talks.

## Physics of Angry Birds Lesson on CUNY-TV

Many thanks to Ernabel Demillo and the crew of Science and U!

You can read more about how we use Angry Birds in class here:
Angry Birds in the Physics Classroom

## Physics Teaching 2.Uh-Oh

My first talk! Given at the STANYS 2011 Physics Breakfast on November 8th, 2011 in Rochester, New York

Links to resources mentioned in the talk:

A huge thank you to Gene Gordon for inviting me to speak at the breakfast. It was great to share my passions and meet my virtual colleagues face-to-face!

I’d love any feedback you have, positive and negative. Thanks!

## Angry Birds in the Physics Classroom

I recently blogged that you can now play Angry Birds in your web browser. This opens up all sorts of video analysis possibilities for physics lessons and assessment. Students can easily make their own videos or you can pre-record your own. Videos can be recorded using Jing, Screencast-O-Matic, or Camtasia Studio. Analysis can be done in Logger Pro or Tracker.

Here are some possible investigations to carry out (shared by Michael Magnuson on the WNYPTA email list):

1. Make a reasonable estimate for the size of an angry bird, and determine the value of g in Angry Bird World. Why would the game designer want to have g be different than 9.8 m/s²?   Download Angry Birds video.

2. Does the blue angry bird conserve momentum during its split into three?  Download Red and Blue Birds video.

3. Does the white bird conserve momentum when it drops its bomb? Why would the game designer want the white bird to drop its bomb the way that it does?  Download White Bird video.

4. Describe in detail how the yellow bird changes velocity.  You will need to analyze more than one flight path to answer this question.  Download Yellow Birds video.

5. Shoot an angry bird so that it bounces off one of the blocks. Determine the coefficient of restitution and the mass of the angry bird.  Download Red Birds and Falling Block video.

Other posts with ideas about how to use Angry Birds in physics class:

How have you used (or will use) Angry Birds in the classroom?

UPDATE 12-28-2011: Our class has been featured on CUNY-TV’s “Science and U!” Jump to 10:25 in the video below: