A great exploration
----perpetual motion machine
Group members:
Xiaoting Pang
Boming Yang
Zhou Fang
Mengxi Song
What’s perpetual motion
machine?
Perpetual motion describes hypothetical machines that operate or
produce useful work indefinitely and, more generally, hypothetical
machines that produce more work or energy than they consume,
whether they might operate indefinitely or not.
Perpetual motion
machine
There is undisputed scientific consensus that perpetual motion would
violate either the first law of thermodynamics, the second law of
thermodynamics, or both. Machines which comply with both laws of
thermodynamics but access energy from obscure sources are
sometimes referred to as perpetual motion machines, although they do
not meet the standard criteria for the name.
The classification
•
A perpetual motion machine of
the first kind
•
A perpetual motion machine of
the second kind
The first kind
•
A perpetual motion machine of the first kind produces work without the
input of energy. It thus violates the first law of thermodynamics: the law of
conservation of energy.
•
The law of conservation of energy is an empirical law of physics. It states
that the total amount of energy in an isolated system remains constant
over. A consequence of this law is that energy can neither be created nor
destroyed: it can only be transformed from one state to another.
•
Hence, it is impossible for a machine to do the work infinitely without
consuming energy.
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Examples of first kind perpetual motion machine
•
Overbalanced Wheel
•
Float Belt
•
Capillary Bowl
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Overbalanced Wheel
•
The "Overbalanced Wheel". It
was thought that the metal balls
on the right side would turn the
wheel because of the longer
lever arm.
•
But! Since the left side had more
balls than the right side, the
torque was balanced and the
perpetual movement could not
be achieved.
The Float Belt
•
The yellow blocks indicate floaters.
It was thought that the floaters
would rise through the liquid and
turn the belt.
•
However pushing the floaters into
the water at the bottom would
require more energy than the
floating could generate!
The Capillary Bowl
•
The "Capillary Bowl". It was
thought that the capillary action
would keep the water flowing in
the tube.
•
But since the cohesion force that
draws the liquid up the tube in
the first place holds the droplet
from releasing into the bowl, the
flow is not perpetual.
The second kind
•
A perpetual motion machine of the second kind is a machine which
spontaneously converts thermal energy into mechanical work. When the
thermal energy is equivalent to the work done, this does not violate the law
of conservation of energy. However it does violate the more subtle second
law of thermodynamics.
•
The signature of a perpetual motion machine of the second kind is that
there is only one heat reservoir involved, which is being spontaneously
cooled without involving a transfer of heat to a cooler reservoir. This
conversion of heat into useful work, without any side effect, is impossible,
according to the second law of thermodynamics.
Example: Carnot heat engine
•
Carnot engine diagram (modern) - where heat flows from a high
temperature TH furnace through the fluid of the "working body"
(working substance) and into the cold sink TC, thus forcing the
working substance to do mechanical work W on the surroundings,
via cycles of contractions and expansions.
•
Second Law of Thermodynamics:
It is impossible to extract an amount
of heat QH from a hot reservoir and
use it all to do work.
•
Some amount of heat QC must be
exhausted to a cold reservoir. This
precludes a perfect heat engine.
•
Although the perpetual motion machine has been
proved a failure, people still attempt to improve their
way to use energy.
•
We try to decrease the energy wasted during the
processes of energy transaction and transportation so
that we can use it more effectively.
The attempt to improve our energy
system
The wind power
Solar energy
hydropower
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Reference
• http://en.wikipedia.org/wiki/Perpetual_motion
• http://www.kilty.com/pmotion.htm#Section4
4/9/2015
Thank you for your time!
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Group members:
Zhou Fang
Xiaoting Pang
Boming Yang
Mengxi Song
04.2011