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Chapter 10
Thermal Physics1. Temperature and the zeroth Law
of Thermodynamics2. Thermometers and Temperature
Scales3. Thermal Expansion
Thermal Physics What is Thermal Physics? What is Heat? What is Thermal Contact? What is Thermal Equilibrium?
Zeroth Law of Thermodynamics
If objects A and B are separately in thermal equilibrium with a third object, C, then A and B are in thermal equilibrium with each other.
Allows a definition of temperature
Thermometers What is a thermometer? A Mercury thermometer Gas thermometer
Temperature Scales How does one
define a temperature Scale?
The Celsius scale The Fahrenheit
scale The Kelvin scale
Kelvin Scale Why do we
need this scale?
What is first point?
What is triple point?
Some KelvinTemperatures Some
representative Kelvin temperatures
Note, this scale is logarithmic
Absolute zero has never been reached
Converting Among Temperature Scales
273.15
932
55
329
95
C K
F C
C F
F C
T T
T T
T T
T T
Converting Among Temperature Scales –Example
1. A pan of water is heated from 25 °C to 80 °C. What is the change in temperature on the Kelvin scale and on the Fahrenheit scale?
Thermal Expansion What is thermal expansion? Linear Expansion Area expansion Volume expansion
Applications of Thermal Expansion – Bimetallic Strip
Thermostats Use a bimetallic strip Two metals expand differently
Since they have different coefficients of expansion
Thermal Expansion – Example
1. A steel railroad track has a length of 30.00 m when the temperature is 0°C. What is its length on a hot day when the temperature is 40°C?
Thermal Expansion – Example
1. A hole of cross-sectional area 100.00 cm2 is cut in a piece of steel at 20°C. What is the area of the hole if the steel is heated from 20°C to 100°C?
Unusual Behavior of Water