In this short problem we investigate the tensions and compressions
in a framework made from springs and ropes.
More Bridge Building
Stage: 5 Challenge Level:
Although this problem is quite open ended, the key objective is for
students to engage with the distribution of tensions and
compressions in a structure as a geometric whole, rather than
focussing on the algebra of a typical calculation. Students should
learn the power of vector methods to understand the mathematical
structure of a problem. Once they develop a feel for the ideas they
should be able to create general statements about structures
without the need for calculation from the onset. This interplay
between geometrical and algebraic arguments is a very important
skill for students to begin to develop.
The ideas covered in this problem extend to more challenging
investigations of real world structures. Great examples are Forth
Bridge in Scotland, the Eiffel Tower and geodesic domes. These can
be used to stimulate discussion about the forces in real bridges
Questions that you may like to pose are: What structural
similarities do real world structures have? Why do you think that
they share these similarities? Why do you think that the designers
chose these structures? How does changing the structure change the
location of the greatest tensions and compressions? How do you
think the forces are distributed amongst all of these objects? Will
there be any net forces at the joints?
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the
NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to
embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities
can be found here.