YOU NEED
String Balance
You can make your own scale with a few strings and
then put it to work weighing small objects.
What to do: Tape the string to the center of the
ruler, making sure that it won't come off. Tie the
free end of the string to the rod of the hanger, as
shown in the illustration.
Attach the other two strings (the
4 inch and the 8 inch strings) so
they are the same distance from
the ends of the ruler. Knot the
free ends of the strings.
Unwind one of the paper clips
and bend it so it fits tightly when
you hang it over the ruler. Slide it
along the ruler until the ruler
hangs straight.
Link 2 paper clips and tie them to
the 8 inch length of string. Then
attach paper clips to the 4 inch
length of string until the ruler is
balanced again.
What happens: You have to attach 4 paper
clips to the 4 inch string to balance 2 paper clips
attached to the 8 inch string.
Why: In the balance scale, the
weight (2 paper clips) multiplied by
the length (8 inches) on one side
must equal the weight (4 paper
clips) multiplied by the length (4
inches) on the other side.
•tape
•three strings of
different lengths: 4
inches (10 cm right
brand; 6 inches (15
cm); and 8 inches (20
cm)
•12 inch (30 cm)
ruler
•wire clothes hanger
•12 small paperclips