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Simulations from PhET  Interactive Simulations
University of Colorado Boulder  http://phet.colorado.edu

Game about moments (the lever law)  Simple moment simulation

Forces and motion  Simulation about the Lever Law

Springs and Hookes Law  Learn about Hookes Law

How friction heats up a surface (Kinetic theory simulation)

Density Learn about density by seeing what floats

Energy Change   Kinetic, potential and intenal energy change

pH scale  Test the pH of different substances

Colour mixing   See what happen when different colours are mixed together

Build an Atom (GCSE)

Refraction (GCSE)

Balancing an equation (GCSE)  

Balancing chemical formula (GCSE)



The magic triangle

A triangle can be made by arranging 4 shapes on a 5 x 13 grid.
By re-arranging the shapes a new triangle can be made.
The  pieces in the lower triangle are exactly the same as those in the upper triangle, but now seem to take up less space so there is one blank square


Where does the white square come from?

Hover your mouse here for the solution

Here is another similar puzzle:

4 similar qudrilateral shapes are arranged into a square.
If each is rotated by 180º they make a similar square but there is a piece missing in the middle.
Where does the extra space come from?

Hover your mouse here for the solution

Bear Puzzle

A bear walks 1 kilometre south, 1 kilometre west and then 1 kilometre north
He ends up in exactly the same place he started.
What colour is the bear?

Hover your mouse here for the solution

4 litres of water problem

You are camping by the edge of a stream and a recipe calls for EXACTLY 4 litres of water.
bottlesUnfortunately, you only have two empty containers, one that holds 3 litres of water and one that holds 5 litres.

How can you get exactly 4 litres (you can fill and empty the containers as many times as you like using water from the stream).

Hover your mouse here for the solution