Have you noticed how many triangles are found in manmade
structures? There is a good reason for that. Even when weak or
flexible materials are used to build triangles they are still
pretty strong. This is because triangles are rigid shapes. 'Test a
Triangle' and see how rigid it is.
You will need:
What to do:
- Tie a knot at one end of a piece of string and thread the other
end through a straw.
- Tie a large knot in the string where it comes out of the
- Thread the string through a second straw and tie another large
knot in it where it comes out of the straw.
- Thread the string through a third straw and tie the string to
the first knot.
- This will form a triangle. Cut off the extra string.
Try to bend your triangle.
Does it bend out of shape easily?
Use additional straws and string to make squares and other
Experiment to see which shapes are the most rigid, that is to
say will bend the least under pressure.
Which shapes do you recommend to use for structures like
buildings and bridges?