1. Temperature and Thermometers
Make use of physical properties that change with temperature.
Many physical properties can be used:
volume of a liquid
length of a solid
pressure of a gas held at constant volume
volume of a gas held at constant pressure
electric resistance of a conductor
color of a very hot object
Thermometers work by quickly getting to the same temperature as its surroundings
Temperature is a measure of how hot or cold something is.

3. A B C Zeroth Law of Thermodynamics
If A is in thermal equilibrium with C and B is in thermal equilibrium with C
Then A and B are in thermal equilibrium. A B C
Temperature and Thermal Expansion.ppt

4. Temperature Scales Kelvin Celsius Fahrenheit Boiling Point (H2O) 373
100
212
Melting
Point (H2O)
273 32
Absolute Zero
-273
-459
Temperature and Thermal Expansion.ppt

6. Let’s consider the way pressure changes with temperature in a gas:
Web Link: Gas Temperature
Pressure
Temperature
Gas 1
Gas 2
Pressure must always be greater than zero
So temperature can never go below this point:
T = ° C = Absolute Zero

7. A new temperature
unit: Kelvins (K)
0 K = absolute zero = ° C
Kelvins are the same size as Celsius degrees
Kelvins are the SI unit for temperature
To convert:
TC = Celsius temp.
T = Kelvin temp.
T = TC

8. Thermal Expansion When the washer is heated The hole becomes larger
Temperature and kinetic Theory13

9. Some consequences of Linear Expansion:
Concrete buildings expand
Bridges need expansion joints
Dental fillings must expand at the same rate as teeth

10. Recall: Most materials expand if heated
Exception: Water contracts from 0°C °C
This is the most dense water gets (in any state)
Consequence:
In the winter, lakes freeze from the top down

11. Thermal Expansion DL Lo DL  LoDT DT DL = aLoDT L - Lo = aLoDT
Coefficient of
linear expansion
L = Lo(1+aDT)
Temperature and kinetic Theory13

12. Thermal Expansion Expansion Problem sleeve shaft D d
A cylindrical brass sleeve is to be shrunk-fitted over a brass shaft whose diameter is cm at 0 oC. The diameter of the sleeve is cm at 0 oC.
To what temperature must the sleeve be heated before it will slip over the shaft?
Temperature and kinetic Theory13

13. Thermal Expansion shaft sleeve Expansion ProblemD d
Expansion Problem
To what temperature must the sleeve be heated before it will slip over the shaft?
Temperature and kinetic Theory13

14. Thermal Expansion Volume Expansion New Volume Lo Lo + DL
Initial Volume
DL = aLoDT
Temperature and kinetic Theory13

15. Thermal Expansion Coefficient of Volume Expansion
Temperature and kinetic Theory13

16. Thermal Expansion Expansion Problem
An automobile fuel tank is filled to the brim with 45 L of gasoline at 10 oC. Immediately afterward, the vehicle is parked in the Sun, where the temperature is 35 oC. How much gasoline overflows from the tank as a result of expansion?
Change in
volume
of the steel
gas tank
Overflow
Change in
volume
of the
gasoline
Temperature and kinetic Theory13