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(^4) PULLEY
A pulley is a rope looped around
a wheel to make a load easier to
lift or move. The more ropes and
wheels are used, the less force is
needed to lift the load, but the
further the rope has to be pulled.
Turning the smaller
gear wheel turns the
larger wheel, which
winds in the rope
As the screw
turns, the longer
end of the lever
is forced down
COMPOUND MACHINE
A device that operates using a
combination of simple machines,
like the one shown here, is called a
compound machine. Human force
is applied only once – to turn the
gear wheel. Each simple machine
applies a force to the next machine
until the tomato is sliced in two.
(^5) INCLINED PLANE
This is a flat surface with ends at
different heights. Moving an
object up an inclined plane reduces
the amount of force needed to lift
it up, but increases the distance it
has to travel.
(^6) WEDGE
This triangular object is used as a
blade to split something or inserted
under an object to lift it. As a
downward force is exerted on the
wedge, its widening shape produces
a sideways force on the object.
(^7) CART WHEELS
These wheels allow the cart to move
smoothly up the ramp. Unlike gear
wheels (1), these are not classed as a
machine, because they do not
change the size of the force applied
to them to help do something.
4
1
3
2
The lever rises, pushing
over a second lever with a
wedge attached
Pivot
As the large gear
wheel moves, it
turns the screw
The rope pulls
the cart up to the
highest point on
the inclined plane
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