matter and energy. welcome back seniors!!! you are the class of 2010 ◦ lead by example seating...
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Matter and Energy
Welcome Back Seniors!!!You are the class of 2010
◦Lead by exampleSeating Assignments and Roll CallPoly Logistics
◦Registration Cards◦Application for Free/Reduced Lunch
Even if unused, this gives you fee waivers on college applications. Fill it out!!!
◦Family Information Guide◦2010 Student Handbook
Syllabus and PoliciesRead over the syllabus for this class
◦You must return the signed acknowledgment form as homework for tomorrow
Policies◦Start of Class◦Dress Code◦Behavior◦Coach Class◦Disciplinary Actions
Matter and Energy
This course is an introduction to the study of thermodynamics and an investigation of how it can be applied to renewable and non-renewable energy sources.
Thermodynamics comes from the Greek words:
therme (heat) + dynamis (force)=
Thermodynamics“the study of systems and energy
transfer”
Matter and Energy
So what is a thermodynamic system?Thermodynamics - “the study of systems and energy
transfer”
Pressure Cooker
Gas-fired Boiler
Geothermal Power PlantSystem – whatever we choose to study
Systems have a boundary and surroundings.
We could be talking about…
Matter and Energy
So what is a thermodynamic system?Thermodynamics - “the study of systems and energy
transfer”
We can choose to study all…
System – what we choose to study
Boundary – separates system from surroundings
Surroundings – everything outside of system
or some part…of a complex system.Always draw the system and its boundaries before starting
any work!!!
Matter and Energy
Let’s practice drawing system boundaries…Thermodynamics - “the study of systems and energy
transfer”
What’s the boundary if I’m interested in the pressure drop of steam as it passes through the turbine?
What’s the boundary if we’re interested in the efficiency of the cooling tower?We’ve been asked to determine the efficiency of the entire geothermal power plant...what should our boundary be?
Matter and Energy
There are two types of systems…Closed Systems – no mass crosses the boundary
Open Systems – mass crosses the boundary
Thermodynamics - “the study of systems and energy transfer”
Matter and Energy
There are two types of systems…Closed Systems – no mass crosses the boundaryOpen Systems – mass crosses the boundary
Thermodynamics - “the study of systems and energy transfer”
“Energy can cross the boundary of both open and closed systems.”
Energy in… Energy out…
Matter and Energy
How do we describe systems?Thermodynamics - “the study of systems and energy
transfer”
Energy in… Energy out…
Property – a characteristic used to describe a system
What are some properties we could use to describe the system above?
MassVolume
MassVolume
TemperaturePressure
TemperaturePressure
We’ve intentionally placed the properties above into two groups. Why do you think that is?
What’s common to the properties in each group? How would you measure each property?If we removed a small amount of mass from the system, which properties would you expect to change?
Matter and Energy
There are two types of properties:Property – a characteristic used to describe a
system
1) Extensive – the whole equals the sum of its parts
Which set of properties are best described as extensive?
MassVolume
MassVolume
TemperaturePressure
TemperaturePressure
2) Intensive – the whole is the same as any partEXTENSIVE
INTENSIVE
Mass and Volume are both extensive properties.Temperature and Pressure are intensive properties.
Extensive properties usually use capital letters as symbols.Intensive properties usually use lower case letters as symbols.
Matter and EnergyProperty – a characteristic used to describe a
systemProperty Symbol
Definition
Mass m measure of the amount of material present
Volume V amount of space occupied by an object
Energy E the ability to do work or produce heat
Temperature
T measure of the molecular activity of a substance
Pressure P force exerted per unit area on the boundaries of a substance
Density ρ the total mass of a substance divided by the total volumeWhat type of property is
density, ρ?What type of property is energy, E?
IntensiveExtensive
Matter and EnergyProperty – a characteristic used to describe a
system
When an extensive property is made intensive by dividing by mass, we use a lowercase symbol and the prefix “specific”.
In general, an extensive property can be made intensive by dividing by the mass of the system.
Extensive Divide by Mass
Intensive
EnergyE
kilojoules, kJ
Energy/massE/m
kilojoules/kilogram
Specific Energye
kJ/kg
Matter and EnergyProperty – a characteristic used to describe a
system
When an extensive property is made intensive by dividing by mass, we use a lowercase symbol and the prefix “specific”.
In general, an extensive property can be made intensive by dividing by the mass of the system.
Extensive Divide by Mass
Intensive
EnergyE
kilojoules, kJ
Energy/massE/m
kilojoules/kilogram
Specific Energye
kJ/kg
Matter and Energy
Homework:Return the signed agreement form attached to your syllabus.Complete the handout you received in classStudy your notes!
*Homework is due at the beginning of class!
Thermodynamics - “the study of systems and energy transfer”
HOMEWORKDefine the following properties:Specific volumeDensitySpecific gravity Humidity