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Every gear has a job to do
Most cars today have automatic windows with levers which
you push to open and close the car’s windows. Some cars
still have manual windows which operate by cranking a
wheel and axle on the inside of the car door. Regardless of
which system is used, the window moves up and down.
How does this happen? Gears are the answer.A system of
gears inside the door shift an arm, which make the window
move up or down.
1. What kind of gears does the K’NEX Car
Window use: spur, crown, rack and pinion,
worm or sprocket gears?
2.
a.
Lower the Car Window all the way and
then turn the crank one full turn to raise
the window.When you turn the crank one
full turn, how much does the blue Gear
turn?
(Note: Be careful not to overwind the
window or the blue Rod will pop off!)
How
much does the yellow Gear turn? What is
the Mechanical Advantage for this gear
system?
b.
Now turn the crank one full turn again
and watch the blue Gear on the top axle
(the Rod with the yellow Gear). How
much of a turn does it make? How does
this compare to the yellow Gear?
c.
Turn the crank fully again and watch the
green Gear. How much does it turn? What
is the ratio between the blue and green
Gears? What is the MA?
d.
Why does the Car Window have this
arrangement of Gears? What would
happen to the Car Window if the
arrangement was reversed? Explain.
3 The K’NEX Car Window uses circular
motion to make the window go up and
down.Turn the handle and observe how
the Gears and the arm that holds the
window work together.Would rack and
pinion gears work well to raise and lower
a car window? Make a drawing to show
how it might work.Then, build a K’NEX
car window using rack and pinion gears.
1
2
3
Window
The Car
Window
STUDENT ACTIVITY SHEET
Summary of Contents for Education Simple Machines Deluxe GEARS
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