Activities/Physics

Description

Physics is a physical world simulator and playground -- you can add squares, circles, triangles, or draw your own shapes, and see them come to life with forces (think gravity, Newton!), friction (scrrrrape), and inertia (ahh, slow down!).

Screenshots

A motor drives the centre cross shape, while the outer edges are pinned to stop the blender breaking.	One motor is used to drive a circle connected via a belt to another pinned wheel that bounces a weight to make a puppet dance.
More puppet dancing	Running dog using two motors
Using a motor on a circle to drive a piston that slowly releases balls one by one	Motor driven earthquake simulator

Ideas to try

• Sorting different sized balls in to two buckets, large and small (with no jams).
• A cyclic mechanism for lifting balls from the bottom of the screen to the top, again and again.
• Try dropping 2 different mass objects at the same time.
• Experiment with pendulums of different lengths and masses.
• Ping pong, can you make a device that hits a ball back and forth across the screen?
• Try building a mechanical binary clock.
• Convert rotation into parallel motion using pistons.
• Experiment with touching one motorised circle against one pinned circle of various sizes.
• Try building a rag-doll puppet and make it dance in a convincing way.
• Use just links and circles to make a structurally sound Eiffel Tower.
• Try building a ratchet mechanism.
• Try building an analogue clock face where the min hand goes around 60 times for each hour.

Tools

Stop/Start allows you to stop time and start it again, allowing you to build without it all collapsing while you work.

Draw click and hold to draw any shape you'd like!

Triangle triangles (equilateral) of any size and initial rotation. Click (center of base) drag + release (tip)

Polygon as many sides as you would like. Draw your own N-gon. Click for each point, to end: right click, or left click in the circle around the original point

Erase click on an object to erase it, or draw a line of destruction--erasing everything in its path!

Motor click an object to pin and drive it with clockwise rotation. It's easiest to pause the simulation, place your object, add its motor, and resume the simulation again.

Box rectangles of any dimension. Click (top-left corner) drag + release (bottom left corner) -- like dragging a selection box in a photo editor

Grab drag existing objects around with the mouse

Pin pin a shape to the screen, it can rotate about the pin. If you want to lock a shape in place use two or more pins to stop it rotating

Circle circles of any radius. Click (center) drag + release (outer edge)

Joint connect two objects together with a rod. Click on any object, drag to another object + release to create a distance joint

Development

There are quite a few code layers to contend with. A regular Python Activity acts as a Sugar wrapper to Physics which is written using OLPCGames which itself wraps Pygame, Physics then uses Elements as a wrapper for Box2D.

Release Notes

v2

• Migrated to Sugar Labs
• Motor toolbar button added
• Pin toolbar button added
• Toolbar reworked for displaying state and keyboard accelerators
• Stop/play toolbar button added
• Prevented very small freehand and polygon shapes to prevent Box2d crashes

v1

• Original created by Brian Jordan, Alex Levenson, Chris Hager

Resources

• Activity bundle
• GIT repository
• Source tarball
• Bug tracker