Cantilever bridges are built with two beams that project toward each other to join and form a span. How do they stay up?
- 5 or 6 notebooks or thin books
What to do:
Stack the notebooks on the edge of a table. Slide the top one halfway out from the stack and over the table's edge. When it balances, slide it back a little. Move out the next notebook along with the top one until they balance, and then slide them back a little. Add another notebook and move the top 3 out and slide them back a little after they balance. Continue in the same way until all the 5 or 6 notebooks are staggered.
The top notebook seems to be suspended in air, but the notebooks do not fall.
You have found the center of gravity, the point at which all the weight of an object seems to be concentrated. Though the top book appears to be suspended in air, more than half the weight of the stack of notebooks is resting on the table.