# Physics of Computer Games

by Ron Kurtus (revised 3 January 2014)

Did you ever wonder what is the sense of learning physics? Many students have wondered the same thing. One interesting area where the principles of physics are extensively applied is in the development of computer games. Objects have to follow the rules of physics to look realistic in a game.

Questions you may have include:

• Where is physics used in games?
• Why must things follow rules of physics?
• What are some examples?

This lesson will answer those questions. Useful tool: Units Conversion

## Areas of physics used in games

Some of the areas of physics that require application and knowledge of the laws of physics are gravity, elasticity, light and sound. Since we see objects behaving according to the physics laws in our everyday lives, any deviation from those rules would make the game or the animation not look real.

Many equations used in physical science are statements of physics laws. The equations are predictions of how an object should behave. Other equations are simple definitions.

Of course, there are some exceptions that are used for dramatic effects, but in general we expect to see things behave as they should.

### Gravity

All falling objects respond to the force of gravity according to the laws of physics. Falling objects accelerate according to certain equations. All objects fall at the same rate, unless they are affected by air resistance.

Likewise, if a game character jumps in the air, that character must come back down to earth according to the rules of gravity. If a game showed objects falling differently than what you normally see, it would not look realistic.

(See The Force of Gravity for more about the subject.)

### Elasticity

Some things bounce better than others, depending on how elastic they are. When you drop a metal ball on the sidewalk, it will not bounce as high as the more elastic rubber ball. Computer game developers must adjust the amount of elasticity of objects, so they will look realistic when they bounce or collide.

### Light

There are certain rules that determine how a beam of light will reflect off an object or how it will bend or refract when going through something transparent. How the light reflects off an object, as well as the shadows formed, determines how realistic things look in the game. The exploration game "Myst" is a good example of using the physics of light to make things look realistic.

(See Visible Light for more about the subject.)

### Sound

Sound characteristics like echoes and the Doppler effect (changing pitch as an object moves by you) are applications of laws of the physics of sound.

One area where the rules of sound are often ignored is in games taking place in space. It is impossible to hear an explosion in outer space, because there is no air or other matter to carry the sound waves. Space movies also have explosions with sound in the vacuum of space. But I guess it would be not as dramatic if they followed the rules of physics too strictly in that situation.

(See Sound Waves for more about the subject.)

## What can you do?

When you play computer games, you can be aware how well objects act as they are supposed to. Your knowledge of physics can also tell why things behave the way they do.

### If programmer

If you are interested in programming and creating your own games, you will need to know the laws of physics and the equations involved. The equations are used in the programming language to determine how an object responds or behaves.

### Name some games

If you have some favorite computer games, examine how well they they follow the physical laws. Let me know, and I'll post the observations.

## Summary

Computer games apply the laws of physics in order that objects in the game behave as they should. Programmers need to know they physical science equations and apply them to the computer code in order to make the game realistic.

You can observe the physical laws in action and see if the game is well-done and truly realistic.

Smile and have fun

## Resources and references

Ron Kurtus' Credentials

### Websites

Physics Resources

### Books

If you have questions, comments, or opinions on this subject, send an email with your feedback. I will try to get back to you as soon as possible.

## Students and researchers

www.school-for-champions.com/science/
physics_of_computer_games.htm

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