Materials Needed:
- Board
- Hammer
- Nails
- Large & small spools
- Rubber band
Procedure: (see Figure 14)
- Hammer two nails into a board far enough apart
to lightly stretch the rubber band between
them.
- Place the large spool over one of the nails and
one of the smaller ones over the other
nail. They should turn freely.
- Slip the rubber band around both spools so when
one spool is turned the other moves.
- Place a mark on the top edge of each spool and
one on the board corresponding.
- Beginning at the mark, turn the large spool through
one complete turn.
- How many times did the small spool turn?
- In which direction did each spool turn?
- Repeat the investigation for different sizes of
spools and note the results.
- What can you do to change the directions of the
spools?
- Does the length of the drivebelt make a difference?
Figure 14: Pulley investigation setup
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Observations:
Drive belts are a form of pulley system that can be used
to turn wheels. Observe the diameters of the spools and see
if there is a correlation between the diameters and the number
of terms ratios. Be sure and note in your data if you twist
the rubber band (figure 8 type configuration) so you can make
proper deductions about direction. Compare spool combinations
at different distances apart also.
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