Zeroth Law of Thermodynamics and Temperature Measurement
THERMODYNAMICS DAY 1
THERMODYNAMICS
study of laws that governavailability of energydirection of energy flowconversion of energy how energy transformations relate
to the properties of matter
ENERGY*
Chemical Electrical Solar Nuclear Mechanical
Kinetic Energy Potential Energy
Internal Energy Energy in transit
– Work– Heat
CONCEPT CHECK An iron rod with temperature T1 is connected
to a copper ring with temperature T2 for a long period of time. If we separate the metals, the final temperature of the iron rod is ___.1. less than T12. greater than T13. less than T24. greater than T25. approximately equal to the final temperature of
the copper ring
ZEROTH LAW OF THERMODYNAMICS
“If objects A and B are separately in thermal equilibrium with a third object C, then objects A and B are in thermal equilibrium with each other.”
CONCEPT CHECK
Two bodies are in thermal equilibrium when ___1. both are insulated.2. both have the same volume.3. both have the same temperature.4. both interact with different bodies at
different temperatures.5. one is cold and the other is hot.
THERMAL EQUILIBRIUM
Two objects in thermal equilibrium with each other are at the same temperature.
CONCEPT CHECK
Which of the following statement(s) about temperature is(are) incorrect?1. Temperature is “hotness”.2. Temperature is a measure of heat.3. Temperature is a measure of kinetic
energy.4. Temperature is what a thermometer says.
TEMPERATURE: MACROSCOPIC DEF’N
quantity that tells how warm or cold a substance is with respect to some standard
TEMPERATURE SCALES
SCALE
Freezing point
of water
Boiling point of water
T
Celsius 0 C 100 C 100 CFahrenheit 32 F 212 F 180 F
Kelvin 273 K 373 K 100 K
TEMPERATURE CONVERSION
FTT CF 325
9
329
5 FC TT
TEMPERATURE: MICROSCOPIC DEF’N
related to the kinetic energies of the molecules of the substance
CONCEPT CHECK
A newspaper article about the weather states that “the temperature of a body measures how much heat the body contains.” Is this description correct?
HEAT
energy transfer from one object to another object as a result of a difference in temperature between the two
TEMPERATURE MEASUREMENT
Temperature cannot be directly measured; but many properties of matter that we can measure depend on temperature.
THERMOMETRIC PROPERTIES
physical properties that change with temperature
16
mercury glass thermometer
volume
gas thermometer
pressure
thermistor
resistance
ear thermometer
EM radiationthermocouple
Seebeck effect
QUESTION
Why does a nurse taking your temperature wait for the thermometer reading to stop changing?
CONDITIONS NECESSARY FOR TEMPERATURE MEASUREMENT
In thermal contact – can exchange energy in the form of heat
In thermal equilibrium – has achieved the same temperature
ZEROTH LAW AND TEMPERATURE MEASUREMENT
Choose reference points Construct a scale Mark temperature readings of the reference
points
MERCURY
BODYREFERENCE
QUIZ (1/4 sheet), show solution
You propose a new temperature scale, with temperatures given in °M. You define 0.0 °M to be the normal melting point of Mercury and 100.0 °M to be the normal boiling point of Mercury.A temperature change of 10.0 M°
corresponds to how many C°?What is the normal boiling point of water in
°M?
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