1. Ch 10 Heat
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2. Temperature Adding or removing energy usually changes temperature
Temperature is proportional to the kinetic energy of atoms and molecules

3. Temperature Temperature is meaningful only when it is stable
Thermal Equilibrium – the state when two objects in physical contact have identical temperatures
Matter expands as temperature increases (thermal expansion)

4. Measuring Temperature
Thermometers
Most make use of a change in the volume of a gas or liquid
Most are thin glass tubes containing mercury, colored alcohol, or colored mineral spirits

5. Measuring Temperature
Calibrating thermometers requires fixed temperatures
Ice point of water – thermometer in equilibrium with a mixture of ice and water at 1 atm
Steam point of water – thermometer in equilibrium with a mixture of steam and water at 1 atm

6. Temperature Conversion
Temperature in Fahrenheit (TF )
Units are °F
Temperature in Celsius (TC)
Units are °C

7. Temperature Conversion
Temperature in Celsius (TC)
Units are °C
Temperature in Kelvin (T)
Units are K

9. Heat and Energy
Heat – the energy transferred between objects because of a difference in their temperatures
Always moves from the object with the higher temperature to the object with the lower temperature

10. Heat and Energy

11. Heat and Energy
The transfer of energy as heat alters an object’s temperature
Energy transfer depends on the difference of temperature of the two objects

12. Heat and Energy
Greater temperature difference = greater amount of energy transferred
At thermal equilibrium, the net energy exchanged is zero

13. Heat (Q)
Heat (Q) has units of energy

14. Internal Energy (U) The energy of a substance due to atomic motion
Units are Joules (J)

15. Internal Energy (U)
Internal energy can be changed through work (friction)
The energy required to overcome friction is transformed into internal energy
Internal energy can also be changed by deforming a solid’s structure
Stretching a rubber band or bending metal

16. Conservation of Energy
½ mvi2 + mghi = ½ mvf2 + mghf + ΔU

17. A device used to demonstrate energy conservation is shown
A device used to demonstrate energy conservation is shown. If a total mass of 11.5 kg falls 1.3 m and all of the mechanical energy is converted to internal energy, by how much will the internal energy of the water increase? (Assume no energy is transferred to or from the surroundings.)