Week 20 (Jan. 5 - 9)
Reading: Temperature (Chap. 19)
Key Topics: temperature measurement, thermometry, thermal expansion, ideal gasses
Key Topics: temperature measurement, thermometry, thermal expansion, ideal gasses
Topics: The zeroth law of thermodynamics; thermometry; practical and absolute temperature scales; constant volume gas thermometry; ice, steam and triple points of water; Fahrenheit, Celsius and Kelvin temperature scales; thermal expansion coefficient; Boyle's and Charles' Laws; ideal gas law
Week 20 Homework Problems:
Week 20 Homework Problems:
- Short essay questions for class discussion:
- In principle, any gas can be used for a constant volume thermometer. Why can you not use oxygen below 15K? What gas might you use?
- Metal lids to glass jars can often be loosened by running hot water over them. How is this possible?
- Why should the amalgam used in dental fillings have the same average coefficient of thermal expansion as a tooth? What would occur if it didn't?
- A mass is suspended from a rubber band. When the rubber band is heated with a hair drier, the rubber band shrinks and the mass is lifted. What does this imply about the coefficient of linear expansion of rubber?
- Explain why a column of mercury in a glass thermometer first descends then rises when placed in a beaker of hot water.
- Markings to indicate length are placed on a steel tape in a room that has a temperature of 22 deg. C. Are measurements made on a warm day, when the temperature is 27 deg. C too long, too short, or accurate? Explain.
- The suspension of a pendulum clock is made of brass. When the temperature increases, does the period of the clock increase, decrease or remain the same? Explain.
- Why don't ponds freeze all the way to the bottom in the winter?
- A constant volume gas thermometer is calibrated in dry ice (solid CO2 has a temperature of -80.0 deg. C) and in boiling ethyl alcohol (78.0 deg. C). The two pressures are 0.900 atm and 1.635 atm. What value of absolute zero does the calibration yield? What is the pressure at the freezing point of water? The boiling point of water?
- A substance is heated from -12 deg. F to 150 deg. F. What is the change in temperature on the Celsius scale? The Kelvin scale?
- A hollow aluminum cylinder 20.0 cm deep has an internal capacity of 2.000 L at 20.0 deg. C. It is completely filled with turpentine, and then warmed to 80.0 deg. C. How much turpentine overflows? If it is then cooled back to 20.0 deg. C, how far below the cylinder's rim is the turpentine surface?
- An air bubble originating from a deep sea diver has a radius of 5.0 mm at some depth h. When the bubble reaches the surface of the water, it has a radius of 7.0 mm. Assuming the temperature of the air in the bubble remains constant, determine the depth h of the diver the absolute pressure at this depth.