Heat

1. Holt Physics, Chapter 10 Heat

3. Defining Temperature • Feeling hot or cold • Need a more precise definition for how “hot” or “cold” something is.

4. Adding or removing energy usually changes the temperature of an object. • Temperature is proportional to the average KE of the atoms or molecules

7. Internal energy – energy of a substance due to the random motion of its component particles. • Equals to the total energy of those particles. • Symbol for internal energy: U • Temperature is meaningful only when it is stable • Warm fruit juice, cold beaker of water • Thermal equilibrium – state in which two bodies in contact with each other have identical temperatures. • It’s how a thermometer works!

8. Matter expands as its temperature increases. • Called thermal expansion • Coefficient of thermal expansion • Peculiarity of water • The expansion of liquids can be used to measure temperature.

9. Measuring Temperature • Make use of a physical change that corresponds to a change in temperature. • Volume of a gas or liquids • Pressure of a gas at a fixed volume • Most common thermometers • Mercury, colored alcohol, or mineral spirits

11. Calibrating a thermometer requires fixed temperatures. • Ice point: 0 oC • Steam point: 100 oC • Temperature units depend on the scale used. • Most widely used today are the Fahrenheit, Celsius, and Kelvin (or absolute) scales. • Celsius and Fahrenheit: differ in ice point and degree size • Celsius and Kelvin: differ in ice point only, degree size same • Celsius and Fahrenheit can be positive, negative, and zero values