4/16/13
Work and Simple Machines
Inclined Plane
Screw
Pulley
Lever
Wedge
Wheel and Axle
4/19/12 Bell work ….
ISN (p. 206)
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Copy the question and answer in a complete
sentence.
1)There are “simple machines” all around our school
building. Make a list of as many examples of simple
machines that you see in our school.
2)How can your arm be used as a simple machine?
____________________________
Paste the notes guide Simple Machines onto page
207 of your ISN.
Also paste the “ Uses for Simple Machines” practice
sheet onto page 209 in your ISN.
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What is work?
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In science, work is done
when a force causes an
object to move in the
direction of the force.
Even the person in this
picture is doing work by
applying force to
make the ball go the
distance.
Work = force x distance
(W= f x d)
TCAP practice problem :
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TCAP practice question….
Answer: “D”
There is a difference between
Force and Work…….
!  Applying
a force doesn t always result in
work being done.
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(Suppose you help push a stalled car. You push and push but
the car doesn t budge. The pushing made you tired, but you
haven t done any work on the car, because the car hasn t
moved.You do work on the car, when the car actually
moves.) Whenever you apply a force to an
object and the object moves in the direction
of the force, you have done work on the
object.
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So when is work done on an
object?
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Work is done on an object
if two things happen:
A) the object moves as a
force is applied
b) the direction of the
object s motion is the
same as the direction of
the force.
Is this lady in the picture
holding the suitcases
doing work?
Machines make work easier…
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A machine is a device that
makes work easier by
changing the size or
direction of the force.
Machines are not just
cars, big construction
equipment, or computers.
You use simple machines
everyday such as
scissors, chopsticks, etc.
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The 6 Simple Machines
Inclined Plane
Screw
Pulley
Lever
Wedge
Wheel and Axle
Inclined Plane
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The Egyptians used simple machines to build the
pyramids. One method was to build a very long
incline out of dirt that rose upward to the top of the
pyramid very gently. The blocks of stone were
placed on large logs and pushed slowly up the long,
gentle inclined plane to the top of the pyramid.
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Inclined Planes
!  An
inclined plane is a
flat surface that is
higher on one end
!  Inclined planes make
the work of moving
things easier.
!  Ex: ramps (on
buildings and
stairways, bath tubs)
!  Brainpop #1: Inclined
planes
Wedges
!  A
wedge is a pair
of two incline
planes that move.
!  Wedges are used
to split things.
!  Examples includes
an ax, a zipper,
or cutting knives,
plows, and
chisels..
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Screws:
are also incline planes
A screw is an incline plane that is wrapped in a spiral
around a cylinder. When a screw is turned a small
force is applied over the long distance along the incline
plane of the screw. Meanwhile, the screw applies a
large force through the short distance it is pushed.
Screw are used mostly as fasteners.
Levers:
! A
lever is a simple machine that has a
bar that pivots at a fixed point called a
fulcrum. Levers are used to apply force
to a load. (--A load is what you are
applying the force on .)
#effort force
(work input)
Resistance
Force (load)"
Fulcrum"
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Example of Levers .
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Common examples
of levers include
crowbars, scissors,
pliers, tin snips and
seesaws. More Levers …
! Other
examples of
levers include
nut crackers,
wheel barrows,
doors, and
bottle openers.
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Your arm acts as a lever
! Other
examples also
include
tweezers, arm
hammers, and
shovels.
! Brainpop#2:
"Levers"
Pulleys
!  Pulley
are simple
machines that have
a grooved wheel.
!  A pulley needs a
rope, chain or belt
around the groove to
make it do work.
!  A load is attached to
the end of the rope
and the input force
is applied.
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Pulleys are all around your
house……
! When
you open a
window blind by
pulling on a cord,
you are using a
pulley.
Wheel and axle
!  A
wheel and axle is
a simple machine
consisting of two
circular objects of
different sizes.
Did you know that faucets
are examples of a wheel and
axle?
!  Other examples include:
(doorknobs, wrenches,
steering wheels)
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4/16/13
WHEEL AND AXEL
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Fan blades are
also examples of a
wheel and axle.
The axel is stuck
rigidly to a large
wheel. Fan blades
are attached to the
wheel. When the
axle turns, the fan
blades spin.
GEARS are Wheel and Axle
!  Brainpop#4:
!  Each
gear in a
series reverses the
direction of
rotation of the
previous gear. The
smaller gear will
always turn faster
than the larger
gear.
"Wheeel and Axle"
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TCAP practice problem:
TCAP Practice problem:
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TCAP practice question….
Answer: “D”
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