Transcript The Wheel and Axle and Pulleys

By Sadie Entwisle, Sarah Ross, and
Mandy McCandless
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The Wheel and Axel
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Pulley
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2)
3)
4)
5)
6)
What it is
How it works
Screws and levers
http://www.youtube.com/watch?v=AXaPr2tANiM
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Screws
Levers
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Incline Plaines and wedges
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1)
What it is
How it works
Inclined Planes
Inclined Planes (continuation)
Wedges
Video’s
Pictures
Bibliography
Compound Machines
About the Compound Machine
Video
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It is a simple lever that rotates in a circle
around a center point or fulcrum
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A wheel and axle is a lever that rotates in a
circle around a center point or fulcrum. The
larger wheel (or outside) rotates around the
smaller wheel (axle). Bicycle wheels, ferris
wheels and gears are all examples of a wheel
and axle. Wheels can also have a solid shaft
with the center core as the axle such as a
screwdriver or drill bit or the log in a log
rolling contest.
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One common way to work a wheel and axle is
by wrapping a rope around a supported wheel
with a lever sticking out. An object can be tied
to the other end. By turning the lever, the rope
either moves the object toward or away from
you.
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The pulley is a simple machine that uses ropes
to lift heavy objects.
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As I stated before, it is a simple machine that uses ropes to
lift heavy objects.
The pulley system consists of one or more pulleys and a
rope or a cable. The number of pulleys used may increase or
decrease the mechanical advantage of the system. Generally,
the higher the mechanical advantage is, the easier it is to lift
the object that is being lifted.
Overall, no matter how easy it is to use the pulley system,
the system itself is not very efficient due to the force of
friction. For example, one has to pull two meters of rope of
cable through the pulleys in order to lift an object one meter.
The Pulley System
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The pulley system consists of one or more pulleys
and a rope or a cable. The number of pulleys used
may increase or decrease the mechanical
advantage of the system. Generally, the higher the
mechanical advantage is, the easier it is to lift the
object that is being lifted.
Overall, no matter how easy it is to use the pulley
system, the system itself is not very efficient due to
the force of friction. For example, one has to pull
two meters of rope of cable through the pulleys in
order to lift an object one meter.
T.O.C
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http://www.youtube.com/watch?v=AXaPr2tANiM
Screws
Levers
Table of
contents
Its a simple machine. Its usually made of metal. It is used to fasten one object
to another, to lift a heavy object, or to move an object by a precise amount.
Two screws of the same pitch and diameter, one on the outer surface of a solid
cylinder and the other on the inner surface of a hollow cylinder, can be
arranged so that one may be driven spirally into the other, as in the common
nut and bolt. The thread on the surface of the bolt is called the external, or
male, screw; that on the inner surface of the nut, the internal, or female, screw.
Since, however, there is much friction in the operation of a screw, the amount
of work put into this machine is much greater than the amount done and the
efficiency is small. The screw is often used for making delicate adjustments of
tools and machines.
In physics, a lever is a rigid object that is used with an appropriate
fulcrum or pivot point to multiply the mechanical force that can be
applied to another object. This is also termed mechanical advantage,
and is one example of the principle movement. A lever is one of the
six simple machines.
An example: http://www.leversgame.com/
Table of
contents
http://www.ag.ndsu.edu/pubs/plantsci/landscap/pp744w.htm
http://sci-toys.com/ingredients/detergents
.html
http://www.infoplease.com/ce6/sci/A0815625.html
http://www.madsci.org/posts/archives/199811/912130550.Bt.r.html
http://library.thinkquest.org/3715
T.O.C
1)
2)
3)
4)
5)
6)
Inclined Planes
Inclined Planes (continuation)
Wedges
Video’s
Pictures
Bibliography
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The inclined plane is a plane surface set at an angle, other
than a right angle, against a horizontal surface. The
inclined plane permits one to overcome a large resistance
by applying a relatively small force through a longer
distance than the load is to be raised.
Ramps, sloping roads, chisels, hatchets, plows, air
hammers, carpenter's planes---all of these are examples of
the fourth basic machine: The inclined plane and its active
twin brother the wedge. In the broadest sense, the wedge
includes all devices for cutting and piercing---everything
from a kitchen knife to the 'Flying Wedge' of football, a
play so effective in splitting the opponents' formation it
was outlawed.
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It is easier to understand how a wedge works by looking
at the inclined plane, which is nothing more than a wedge
sliced in half. The wedge does its job by moving... the
inclined plane is held stationary while the "wedged
material" is moved over it. The secret of the plane's
mechanical advantage lies in its ability to split the force of
gravity into two smaller forces; one perpendicular to and
one parallel to the plane. It is only the parallel force which
needs to be counteracted by pushing an object laying on
the plane. If there is no friction on the plane, the pushing
effort required will be 1/10th the weight if the length of
the plane is 10 times its height. A similar relationship
holds for any plane: the extra distance makes it possible to
apply an effort smaller than the weight.
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The wedge is the active twin of the inclined plane. It
does useful work by moving. In contrast, the inclined
plane always remains stationary. This simple
machine consists of a pair of inclined planes set faceto-face, that can sustain relative sliding or rolling
motion. By moving one plane relative to the other, a
wedge is capable of building up enormous force in a
direction perpendicular to that of the moving wedge.
Force multiplication varies inversely with the size of
the wedge angle; a sharp wedge ( small inclined
angle ) yields a large force. With adequate friction at
the interfaces, the wedge becomes a separating,
holding and stopping device with countless
mechanical applications.
Cute Video
Experiment Video
All About Simple Machines Video
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http://www.weirdrichard.com/wedge.htm
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http://www.weirdrichard.com/inclined.htm
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For pictures and videos I went to these
websites and Google images/video’s.
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The compound Machine
Video
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A compound machine consists of two or more
simple machines put together. In fact, most
machines are compound machines. Compound
machines can do more difficult jobs than
simple machines alone. Their mechanical
advantage is far greater, too. Some examples
are a pair of scissors and a bicycle.
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Example:
http://www.youtube.com/watch?v=0IdaQa7v
p04
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