2. How’s the temperature in here? Fire is hot and snow is cold. But if you want to measure the temperature in here, you need a thermometer.

3. HotCold Hot vs. Cold Atoms are in constant motion. Atoms in the gas phase are zooming around the room. (Translation) In the solid phase, the atoms can’t move from place to place, but they can shake back & forth. (Vibration) When something feels hot, the atoms inside it are moving very fast. link

4. Thermometers Galileo invented the 1 st thermometer in 1592. Didn’t have a scale though.

5. Thermometers Liquid-in-glass thermometers – 1630’s No standard! Each scientist had his own scale divisions. Couldn’t compare temperatures in different places.

6. Thermometers Early 1700’s: developed standards Fahrenheit (1686-1736) invented alcohol & mercury thermometers. Proposed 1 st scale: 32  F = freezing point of water & 212  F = boiling point of water at 1 atm.

7. Thermometers Celsius (1701-1744) Proposed 0  C = freezing point of water. 100  C = boiling point of water.

8. Source: http://eo.ucar.edu/skymath/tmp2.html#Tmp

9. How do thermometers work? Molecules are in constant motion – they have kinetic energy. Air molecules collide with the glass. Kinetic energy is transferred to the glass & then to the liquid through the collisions.Air molecules collide with the glass. Kinetic energy is transferred to the glass & then to the liquid through the collisions. Molecules in liquid move faster and spread apart. Length of liquid in column changes.Length of liquid in column changes.

10. Absolute Zero Postulated by Kelvin in 1848. At absolute zero, the atoms are stopped. Outer space is 3  above absolute zero. Absolute zero = 0K = -273.15  C.

11. Lowest Temperature Ever 20 billionths of a degree above absolute zero (0K) Press Release

12. Comparison of 3 Temperature Scales source

13. Degree Size Kelvin & centigrade scales, 100  between freezing pt. & boiling pt. of water. So degrees are the same size; scales are offset. Fahrenheit scale has 180  between freezing pt. & boiling pt. of water. More degrees, so they must be smaller.

14. Conversions between scales K =  C + 273 Or  C = K – 273

15. Temperature Conversions -150  C -100  C -45  C 0  C 38  C 85  C 115  C 200  50K 100K 150K 200K 250K 300K 350K 400K 123K 173K 228K 273K 311K 358K 388K 473K -223  C -173  C -123  C -73  C -23  C 27  C 77  C 127  C

16. Temperature vs. Heat Is temperature the same thing as heat? No. Temperature doesn’t depend on how much matter you have, but heat does.No. Temperature doesn’t depend on how much matter you have, but heat does. For example, does it cost more to heat a swimming pool up to 40  C or a teacup to 100  C?

17. So what is temperature? Temperature is a measure of the average kinetic energy of the particles of a system.Temperature is a measure of the average kinetic energy of the particles of a system.

18. What is Heat? The energy that flows from a hot object to a cold object.The energy that flows from a hot object to a cold object. Heat is a form of energy.Heat is a form of energy.