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OBJECTIVES:
What is a machine? A machine is any device that
can apply mechanical energy at one point and deliver it in
a more useful form at another point. Simple machines are
all around us and help us accomplish work faster and easier
many times each day.
In this demonstration you will use an inclined plane to move
a heavy load. Examples of inclined planes include: ramps
for wheelchairs, car ramps in parking structures, a playground
slide and boat ramps.
STEPS TO FOLLOW:
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Stack the books on a tabletop or the floor.
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Lean one end of the board on top of the stack of books and the other end of
the board on the tabletop (or floor).
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Tie the string around the rock.
Using the string, lift the rock from the tabletop (or floor) to the top of
the stack of books (vertically).
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Now use the inclined plane.
Using the string pull the rock up
the inclined plane from the tabletop (or floor)
towards the top of the books.
Note the difference of force applied using the inclined plane.
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Optional: Steps 6-9
Experiment with different heights by adding or removing
books under the inclined plane. Is it more difficult to move the
rock
over a
steep incline a short horizontal
distance or a gradual incline over a longer horizontal
distance?
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MATERIALS:
2-4 Books
"Fist-Sized" Rock, Large Potato Or Other Object Of Similar Weight
String
Small Board Or Heavy Cardboard For The Inclined Plane
Optional:
Ruler
Small Toy Truck
Transparent Tape
Long Heavy Rubber Band Or Rubber Band Strips
Safety Scissors
Sheet of Rough Sandpaper
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Experiment with effects of friction.
Do wheels on the
object improve the advantage of the ramp (inclined plane)?
Place the rock on a small toy truck.
Now pull it up the inclined plane.
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Would a rough object sliding
on a rough ramp require more force to raise the object
than simply lifting the object? Tape rough sandpaper
to the top surface of the inclined plane. Now pull the rock up the
inclined plane.
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Tie the rock to a rubber
band and measure the rubber band's stretch as the rock is lifted up
vertically and parallel to the inclined plane.
The length the rubber band stretches
is related to the amount of force applied.
Using the ruler, measure the length of
the rubber band in each case.
In which situation does it stretch more?
(You might want to try this with the sandpaper on and off of
the inclined plane.)
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