KNEX Education Simple Machines Deluxe GEARS, Руководство для учителей

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Every gear has a job to do
When a car makes a right turn around a corner, the
wheels on the right side of the vehicle make a small
curve near the curb, but the wheels on the left travel in
a big curve.The left wheels have to travel farther than
the right wheels, but all of the wheels do this action in
the same period of time.That means that the left wheels
actually have to go faster than the right. But how can
they go faster when the left and right wheels are
attached to the same axle? A differential is a set of gears
that lets the left and right wheels turn at different
speeds.
1. Build the Axle model, as shown in Figure A
in the instructions, and test it. Push it
straight over a rough surface, like a carpet.
Explain what happens. Push the model
around a sharp turn.What do you notice?
Describe what happens when this model
makes a turn.Why does this happen?
2
a.
Now, build the Axle with Differential,
as shown in figure B in the instructions.
Roll the Axle with Differential straight
over a rough surface. Observe the cluster
of Gears that make up the Differential.
Which Gears turn and which Gears don’t?
Record your observations.
b.
Continue to roll the Axle with
Differential along and have it make
a sharp turn.Watch the cluster of Gears
move as you make a turn with the Axle
with Differential.What do you notice
about how the model turns now? Which
Gears are working? How does the cluster
of Gears affect the turning? Describe the
action of turning a corner with the use of
the Differential.
3. A differential is a complicated, yet very
clever gearing machine.What machines,
other than a car, could benefit from the
use of a differential gearing system?
Work with a partner to brainstorm
a list of machines.
2
3
1
The Differential
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