temperature: fahrenheit, celsius, and kelvin. temperature vs. heat with your neighbor, try to...
TRANSCRIPT
Temperature:Fahrenheit, Celsius, and Kelvin
Temperature vs. Heat
With your neighbor, try to distinguish between temperature and heat.
(Qualitatively and Quantitatively)
Thermal Energy (Heat) & Temperature
• How would you describe the temperature of a steaming cup of coffee?
• If you said it is “hot” do you mean: A) It has high temperatureOr B) It has a large amount of thermal energy?
• Let’s think about Temperature and Thermal Energy and see if there is a difference.
Temperature
• Operational Definition: Defined in terms of how a property is measured.
-Thermometers have a liquid that when placed in contact with another body either expands or contracts.
-To be useful, a thermometer needs a scale with major and minor delineations
Celsius
• 1742 Swedish astronomer, Anders Celsius used a mercury thermometer and defined his scale in terms of critical points of pure water.
Advantages:-Reproducible-Scale of 10
Disadvantages:-Arbitrary zero value-Negative numbers
TC (TF - 32°)CONVERSION
Kelvin
• 1848, British scientist, William Thomson Lord Kelvin developed a scale that relies on the average kinetic energy of atoms.
Advantages:-Absolute scale-Empirical-No Negatives-Still a scale of 10
TK = TC + 273CONVERSION
Temperature
• Roughly speaking, temperature is a comparative measure of hot and cold
• Kelvin is based on measuring the average kinetic energy of atoms in a sample…
Thermal Energy
• The sum of the kinetic and potential energies of the atoms/molecules in a body. Thermal Energy is also referred to as INTERNAL Energy.
• Temperature in the basic sense, is a measurement of hot and cold.
• Specifically, temperature gives us a measure of the average kinetic energy of particles in a sample
• Heat represents the total kinetic energy of particles in a sample
Temperature vs. Heat
Temperature
Peak emittance wavelength[65]
of black-body radiationKelvin Degrees Celsius
Absolute zero(precisely by definition) 0 K −273.15 °C cannot be defined
Coldest temperatureachieved[66] 100 pK −273.149999999900 °C 29,000 km
Coldest Bose–Einsteincondensate[67] 450 pK −273.14999999955 °C 6,400 km
One millikelvin(precisely by definition) 0.001 K −273.149 °C 2.89777 m
(radio, FM band)[68]
Water's triple point(precisely by definition) 273.16 K 0.01 °C 10,608.3 nm
(long wavelength I.R.)
Water's boiling point[A] 373.1339 K 99.9839 °C 7,766.03 nm(mid wavelength I.R.)
Incandescent lamp[B] 2500 K ≈2,200 °C 1,160 nm(near infrared)[C]
Sun's visible surface[D][69] 5,778 K 5,505 °C 501.5 nm(green-blue light)
Lightning bolt'schannel[E] 28 kK 28,000 °C 100 nm
(far ultraviolet light)Sun's core[E] 16 MK 16 million °C 0.18 nm (X-rays)
Thermonuclear weapon(peak temperature)[E][70] 350 MK 350 million °C 8.3×10−3 nm
(gamma rays)
Sandia National Labs'Z machine[E][71] 2 GK 2 billion °C 1.4×10−3 nm
(gamma rays)[F]
Core of a high-massstar on its last day[E][72] 3 GK 3 billion °C 1×10−3 nm
(gamma rays)Merging binary neutronstar system[E][73] 350 GK 350 billion °C 8×10−6 nm
(gamma rays)
Relativistic HeavyIon Collider[E][74] 1 TK 1 trillion °C 3×10−6 nm(gamma rays)
CERN's proton vsnucleus collisions[E][75] 10 TK 10 trillion °C 3×10−7 nm
(gamma rays)Universe 5.391×10−44 safter the Big Bang[E] 1.417×1032 K 1.417×1032 °C 1.616×10−27 nm
(Planck Length)[76]
Physical Properties that Depend on Temperature
Temperature Scales
• Fahrenheit (oF)*Introduced in 1724*Defined by 2 fixed points based on the properties of water (32-
freezing pt/212-boiling point)*First modern thermometer (Hg)
• Celsius (oC)*Introduced 18 years later (1742)
*Defined by setting boiling point of water to 0o and boiling point to 100o
*Absolute zero in Celsius is -273.15o
• Kelvin*Introduced 1848*Zero point set to Absolute Zero
Converting Between ScalesCelsius and Fahrenheit
oC = 5/9(oF – 32)
oF= 9/5o + 32
K= oC + 273
Converting Between ScalesCelsius and Kelvin
Practice
• Convert 32oF into Celsius (Proof of Concept)
Practice
• Convert 32oC into K
Practice
• Convert 580oF into K