Stage: 5 Short Challenge Level:
Before attempting this problem is it interesting to ask students to
make a scale sketch of their best intuitive guess at the
Once the answer is found the students can compare their intuition
with reality. Were they roughly correct? Does their answer give
them any clues as to the form of a larger compound structure?
Ask students to explain in words why their structures only just
balance, as producing a clear verbal explanation will reinforce the
understanding of the underlying mechanical principles.