Laws of Nature Wk4 Envs321 2011

ENVS 321:
Nature of Science & Science of Going Green
Peninsula College
Perry Spring & Brian Hauge
Spring 2011

Physical and Chemical Laws
 All Biological system controlled by these
o Laws of Motion (Classical Mechanics)
o Newton’s Law of Universal Gravitation
o Thermodynamic Laws
o Gas Laws
o Einstein’s Laws (Quantum Mechanics)
2ENVS321: Nature of Science & Science of Going Green Spring 2011

Scientific “law”
 A scientific law can often be reduced to a
mathematical statement, such as E = mc²; it's a
specific statement based on empirical data, and its
truth is generally confined to a certain set of
conditions.
 scientific theory synthesizes a body of evidence or
observations of particular phenomena. It's generally –
but not always -- a grander, testable statement about
how nature operates.

Laws of Motion
 Newton’s 1st Law (N1L): a body at rest, remains at rest, a
body in motion, remains in motion at a constant velocity
unless acted upon by a net force
 Newton's 2nd law (N2L): the acceleration of a body that is
acted up by a net force is proportional to the magnitude
of the net force and inversely proportional to the body’s
mass
 F = m*a => Force = mass * acceleration
 if mass remains constant!

Newton’s Laws continued:
 Newton’s 3rd Law (N3L): When a 1st body exerts a force
upon a 2nd body, the 2nd body exerts an equal force in the
opposite direction on the 1st body.
 Paraphrased: for every action, there is an equal and
opposite action.
 If acceleration = 0, then sum of the forces = net forces = 0
 Newton’s Law of Universal Gravitation: any two objects,
no matter their mass, exert gravitational force toward
one another F = G × [(m1m2)/r²]

Newton’s Laws continued:
http://www.youtube.com/watch?v=iH48Lc7wq0U

Kinetics & Mechanics
 Kinetics provides a mathematical method of analysis of
the physics of mechanics
 Velocity (v) : distance / time v=s/t
 Acceleration (a) : velocity / time a=s/t2
 Mass (m) : the quantitative measure of inertia
 Force (F) : Net Force = mass * acceleration F= m*a
 Gravity: all bodies which fall near earth’s surface have
the same downward acceleration
9.8 meter/sec2 or 32 feet/sec2

Work, Force, & Energy
 Force is to push or pull
 Ex: push is the force applied to the door marked pull
 Work = Force times Distance
W= F * s = m * s / t2
 Energy is the ability to do work

Contrasting Heat with Work
 Heat is the transfer of energy due to a difference in
temperature.
 Work is the transfer of energy by a process other than
heat

Energy
o Kinetic energy
o Potential energy
o Thermal energy
o Magnetic energy
o Chemical energy
o Electrical energy
o Radiant energy
electromagnetic radiation
 Mechanical energy
 Luminous energy
 Nuclear energy
 Elastic energy
 Sound energy
 the amount of work that can be performed by a force
 Many FORMS of Energy:

Key Definitions
 Potential Energy- energy of position
or stored energy
 Batteries store chemical energy as
potential energy
 Combustion of wood releases
stored solar energy giving off heat
and light energy
 Kinetic Energy- energy of movement
 Moving wind and moving water can
be mined for their kinetic energy to
create mechanical energy which
can create electrical energy

Heat and Temperature
 Temperature is roughly the average kinetic energy
in a substance
 Heat is the process of energy transfer from one
body or system to another due to a difference in
temperature.
 Thermal energy is a form of energy that
manifests itself as an increase of temperature.
Spring 2011 12ENVS321: Nature of Science & Science of Going Green

Thermodynamic Laws
 The zeroth law of thermodynamics allows the assignment of a
unique temperature to systems which are in thermal equilibrium
with each other.
 The first law of thermodynamics mandates conservation of
energy and states in particular that the flow of heat is a form of
energy transfer.
 The second law of thermodynamics states that the entropy of
an isolated macroscopic system never decreases, or, equivalently,
that perpetual motion machines are impossible.
 The third law of thermodynamics concerns the entropy of a
perfect crystal at absolute zero temperature, and implies that it is
impossible to cool a system to exactly absolute zero.

Thermodynamics
 Zero law – heat transfers until equilibrium
 warm to cold transfer

1st Law of Thermodynamics
 Conservation of energy - can’t be created or destroyed
http://www.youtube.com/watch?v=BVxEEn3w688

Thermodynamics
 2nd law – entropy of the universe is always increasing;
randomness prevails
 No perpetual motion, no breaking even.

3rd Law of Thermodynamics
Absolute zero can’t be reached - who would want to!
0 o
K = - 273 o
C = - 459 o
F
How Stuff Works: 10 Scientific Laws
& Theories You Really Should Know

Entropy

19
ENVS321: Nature of Science & Science of Going
GreenSpring 2011

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GreenSpring 2011

Units of Energy

Energy – Matter Equivalence
 http://www.youtube.com/watch?v=AgwDNLBRqjQ
From brightstorm.com/science

Solar Energy for Living things
 Photosynthesis
 Respiration

Biomimicry & Solar Leaf
 A Massachusetts Institute of Technology (MIT) research team, lead by Dr. Daniel Nocera,
have created a functioning artificial leaf which in reality is an advanced playing-card sized
silicon+catalyst solar cell that can power a house in a developing country for a day using a
gallon (3.79 liters) of water and sunlight.
 At the 241st National Meeting of the American Chemical Society in Anaheim, California,
Dr. Nocera announced that the MIT artificial leaf mimics photosynthesis using
inexpensive nickel and cobalt catalysts to perform electrolysis, splitting water into
hydrogen and oxygen, and converts energy up to ten times more efficiently than a
natural leaf.
 “A practical artificial leaf has been one of the Holy Grails of science for decades,”
explained Nocera. “The artificial leaf shows particular promise as an inexpensive source
of electricity for homes of the poor in developing countries.”
 The oxygen and hydrogen can either be passed through a fuel cell to generate electricity,
or burned to generate heat. All the leaf needs is water and sunlight, and it will work for at
least 45 hours without degrading in performance according to testing done in the lab.
 John Turner at the U.S. National Renewable Energy Laboratory developed the first
artificial leaf over a decade ago, but it worked for only a day and was too expensive for
practical applications.
- 30 March 2011 in GreenMuze 28 March 2011 in InHabit
Spring 2011ENVS321: Nature of Science & Science of Going Green 24

Spring 2011
Green 25
Their future is in our hands.
As stewards of our children’s planet, we are
faced with an incredible challenge. We must
lay the groundwork for a built environment
that thrives within the reality of increasingly
limited resources and foster an economy that
serves the triple bottom line.
A tall order to be sure, but not impossible.
When the green building movement’s leading
thinkers and practitioners come together to
share their deep expertise and dearest hopes,
we can leap ahead as a movement and as a
society. Living Future, Cascadia’s annual
unconference, offers a unique forum for
exactly this kind of gathering.
.
http://vimeo.com/19904690

Thermal Mass
 Thermal mass is effective in improving building
comfort in any place that experiences these types
of daily temperature fluctuations -- both in winter
as well as in summer.
 When used well and combined with passive solar
design, thermal mass can play an important role in
major reductions to energy use in active heating
and cooling systems and hence the reduction of
greenhouse gas emissions due to fossil fuel
burning in power stations.

Heat transfer
 Heat transfer is the transition of thermal energy or
simply heat from a hotter object to a cooler object
 three methods of heat transfer (convection,
conduction and radiation).

Heat transfer via RADIATION
 Radiation is the transfer of heat energy through empty
space. No medium is necessary for radiation to occur;
radiation works even in and through a perfect vacuum.
The energy from the Sun travels through the vacuum
of space before warming the earth.

Heat transfer via CONDUCTION
 Conduction is the transfer of heat by direct contact
of particles of matter. In other words, heat is
transferred by conduction when adjacent atoms
vibrate against one another, or as electrons move
from atom to atom. Conduction is greater in
solids, where atoms are in constant contact. In
liquids (except liquid metals) and gases, the
molecules are usually further apart, giving a lower
chance of molecules colliding and passing on
thermal energy.

Heat transfer via CONVECTION
 Convection is the transfer of heat energy between a
solid surface and the nearby liquid or gas in motion.
As fluid motion goes faster the convective heat transfer
increases. The presence of bulk motion of fluid
enhances the heat transfer between the solid surface
and the fluid.
 Two types:
 Natural convection
 Forced convection

Laws of Nature Wk4 Envs321 2011

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