Materials Needed:
- Plastic gears of different sizes (3)
- Mounting board
- Axles
Procedure: (see Figure 15)
- Mark one tooth of each gear.
- Count and record the number of teath on each gear.
- Mount the largest and smallest gears of different
sizes so their teeth
mesh and their marks are aligned at the
intersection point.
- Turn the small gear to the right (CW) 1 revolution.
- Record the direction and number of revolutions
the large gear travels.
- Return the gears to the start position and this time
turn the large gear to the right (CW) 1 revolution.
- Record the direction and number of revolutions
the small gear travels.
- Repeat steps 3 through 7 using the largest and
middle sized gears.
- Repeat steps 3 through 7 using the smallest and
middle sized gears.
- Try some variations in revolutions or other sizes.
Figure 15: Gear investigation setup
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Observations:
The mechanical advantage in gears is determined
by the ratio of the number of teeth on the gears.
The pitch of a gear describes the number of teeth that
can be put on a 1-inch diameter gear. Gears with
different pitches will not fit together well, so the
same pitch must be used throughout the transmission.
Gears in 48 and 64 pitch are the ones most often
used in slot cars. You can buy gears for the 1/24 scale
slot cars at hobby shops.
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