Heat and Temperature

1. Heat and Temperature

2. Temperature • The measure of the average kinetic energy of all of the particles within an object.

3. Temperature and Energy • All particles are moving and have kinetic energy. • We can not measure the KE of each molecule, so we take an average of each one. • Taking temperature is finding the average KE of molecules. • Feeling hot or cold is a rough estimate. • It is subjective.

4. Thermometer • A device that measures temperature • Most thermometers rely on the expansion of either fluids or metal (mercury) to work. • Electric thermometers rely on a change in current.

5. Temperature Scales

6. Celsius-Fahrenheit Celsius – Fahrenheit Conversion Equation Fahrenheit temperature = (9/5 X Celsius temperature) + 32.0 TF = 9/5t + 32.0

7. Fahrenheit-Celsius Fahrenheit – Celsius Conversion Equation Celsius temperature = 5/9 (Fahrenheit temperature – 32.0) T = 5/9(TF– 32.0)

8. Kelvin • Based on Absolute Zero (theoretical) • The temperature at which an object’s energy is minimal Celsius – Kelvin Conversion Equation Kelvin temperature = Celsius temperature + 273 T = t + 273

9. Relating Temperature to Energy Transfer as Heat You feel hot and cold because of transfer of energy. Molecules must come into contact with one another. Hot = absorbing energy from object Cold = releasing energy from object

10. Heat The transfer of energy from the particles of one object to those of another object due to a temperature difference between the two objects

11. Thermal Energy

12. Thermal Energy

13. Thermal Energy

14. Thermal Energy

15. Thermal Energy

16. Thermal Energy

17. Thermal Energy Equation Q = m ΔT C Q = change in thermal energy (J) m = mass (kg) ΔT = change in temperature (˚C) C = specific heat (J/kg ˚C)

18. Problem Plug and Chug Q = 0.5 kg • 60 ˚C• 800 J/kg ˚C mass x change of temp x specific heat Q = 24,000 J