Experiment of the Month
Last Month's Challenge
The Question
Balancing Act
What to do
Balance a ruler on the edge of a table, by hanging a hammer on the end
of the ruler with a piece of string.
How on earth do you do that?
I won't tell you, but remember that things are more stable with a lower
centre of mass.
The Answer
Balance the ruler as shown in the picture. The ruler is placed on the end
of the table and the butt of the is held underneath by a loop of string.
The string and hammer act as a lever on the ruler, exerting an upward force
on the end of ruler, stopping it from falling down. (You can actually use
a folding ruler with the hinge on the lower side of the ruler). The head
of the hammer is below the level of the table, so the system is stable.
Anything with a centre of mass below the base will be stable. You can humming
bird ornaments that balance by their beak on a small stand which work by
having weights in their wings which are shaped so as to be below the level
of the stand. This works on the same principle.
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