2. What is it? How do we measure it? By Bob Flinn

3. Temperature is the measurement of energy in a molecule. The higher the temperature, the greater the energy. As an object increases in temperature, it almost always expands in size. Likewise, it contracts when cooled. Two objects of different temperatures will give off and absorb heat energy until they are in thermal equilibrium. (somewhere between the difference of the two) Heat energy is not lost, it is transferred to other objects. (Conservation of energy)

4. All objects conduct heat, that is, they allow for the transfer of heat energy from the higher ‘state’ (temperature) to the lower state. Metals are generally good conductors of heat. Temperature moves through them quickly. Objects that conduct heat poorly are called an insulator. Generally, the less dense something is, the better it resists heat conduction.

5. A thermometer is an instrument that measures the temperature of a system in a quantitative way. It is made with a substance that has the property of changing volume in a regular way as the temperature changes.

6. Galileo used a thermoscope for measuring temperature in 1610. It used the air in the bulb to expand and contract with changes in temperature. Marks on the tube allowed for a measure of change, but no calibration was done. Galileo is also credited for creating the ‘Galileo thermometer’ that measures temperature by the floating and sinking of bulbs in water. The density of the water changes with temperature, so the bulbs float or sink at different density points.

7. Daniel Gabriel Fahrenheit Gabriel Fahrenheit, an instrument maker of Däanzig and Amsterdam was the first to use mercury as a fluid in a closed thermometer in 1724, Fahrenheit described how he calibrated the scale of his mercury thermometer: "placing the thermometer in a mixture of sal ammoniac or sea salt, ice, and water a point on the scale will be found which is denoted as zero. A second point is obtained if the same mixture is used without salt. Denote this position as 30. A third point, designated as 96, is obtained if the thermometer is placed in the mouth so as to acquire the heat of a healthy man.“ 1 Later Fahrenheit determined the boiling point of water to be 212 o and he adjusted the freezing point of pure water from 30 o to 32 o to make the difference a more rational 180. Used in U.S.A. for temperature reporting Fahrenheit scale Water freezing32 boiling212

8. Anders Celsius In 1745, Carolus Linnaeus of Upsula, Sweden, described a scale in which the freezing point of water was zero, and the boiling point 100, making it a centigrade (one hundred steps) scale. Anders Celsius (1701-1744) used the reverse scale in which 100 represented the freezing point and zero the boiling point of water, still, of course, with 100 degrees between the two defining points. In 1948 use of the Centigrade scale was dropped in favor of a new scale using degrees Celsius (° C). Celsius scale Water freezing0 boiling100 This scale is used by scientists and weather reporters around the world (except the U.S.A.)

9. A degree of Celsius is larger than a degree of Fahrenheit. (1.8 times bigger) Body temperature is 98.6 o F = 37 o C Comfortable room temperature of 72 o F = 22 o C Hot tap water is approximately 140 o F = 60 o C At -40 o F it is also -40 o C – the only time it happens in the two scales!

10. Kelvin scale Water freezing273 boiling373 William Thomson, lord Kelvin Lord Kelvin, (1824-1907) was involved with research and the theory of the nature of temperature and its relation to energy. With James P. Joule, Lord Kelvin came up the idea of an absolute zero. At this temperature, a gas would have no pressure, thus molecules would stop moving. As the theory developed, he also penned the laws of thermodynamics. He did much research with electricity, laid transoceanic telegraph cables, and headed the commission creating the Niagara Falls generating plant using alternating current electricity. The Kelvin scale was officially made a part of SI in 1967/68 in his honor. The Kelvin scale has no negative numbers. It is abbreviated with a capital K (do not use the term or symbol degree)

11. Since objects expand and contract as temperature changes, it must be allowed for in construction. Bridge expansion joint Nail slots to allow for expansion Bridge ‘rocker’ support to allow for expansion Sidewalk expansion joint. The slab on the left been lifted, creating a ‘step.’

12. 1.Fill bottle about quarter full with alcohol/water mixture. 2.Push straw through hole in bottle cap. 3.Push straw into cap until it is about 1 cm from bottom (when cap is screwed on). 4.Seal straw to cap with clay. 5.Tighten cap after forcing liquid part way up the straw. (squeeze bottle, then pinch straw to hold liquid in straw.)

13. 1.Tape a piece of cardstock to the straw above the clay stopper. 2.Measure the temperature of the air with a calibrated thermometer. 3.Mark the level of the liquid with that value on the card. 4.Place your thermometer in pan of ice water. (Movement of liquid column stops) 5.WAIT for EQUILIBRIUM. (Movement of liquid column stops) 6.Mark the new temperature value on the card. 72

14. Have students measure the temperature at various places in the room. Where is it hottest? Coolest? Place 2 thermometers in sunlight, one under white paper, one under black paper. How hot, cold is your tap water? Drinking fountain? Cafeteria milk? Convert Fahrenheit to Celsius. Is 20 o C hot or cold? Put thermometer is ice. Then add salt. What happens to the temperature?

15. °C Fact +5700Temperature at the Sun's surface +1760Temperature of a Bunsen burner flame +1500Iron melts +1065Gold melts +962Silver melts +100Water boils +57Highest recorded temperature on Earth +37Human body temperature +18 to +20 Room temperature 0Water freezes -37Car antifreeze freezes -70Lowest recorded temperature on Earth -273Absolute zero

16. Bibliography ( 1 ) D. G. Fahrenheit, Phil. Trans. (London) 33, 78, 1724 http://eo.ucar.edu/skymath/tmp2.html About Temperaturehttp://eo.ucar.edu/skymath/tmp2.html http://en.wikipedia.org/wiki/Temperature