Physics Activities / Ver. / 0.3.4
Last updated / 11.01.02
Activities for Section 3.1
Activitities are unassessed short experiments with some problems (pre questions, post questions, and syllabus questions) assigned. These problems will be a starting point for class discussion on the material after the activities. Due to time restrictions some of the problems will be given as homework.
Text book reference:
Chapter 10 - Thermal physics - pp. 100-110 of
David Sang, Physics 2. Cambridge Advanced Sciences,
Cambridge University Press 2001, ISBN 0-521-79715-2
A.1 Defining a Temperature Scale Operationally
Aim
The aim of this activity is to define a temperature scale of your own. In addition the direction of thermal energy transfer is determined between the thermometer and the objects.
Syllabus reference
3.1.1, 3.1.2, 3.1.3
Group size
Two
Equipment needed
Glass thermometer, ruler (lab station)
Transparent tape
Marking pen
Various objects of interest (salt, tap water, water ice, dry ice,….)
Procedure
1. Seal the scale of the glass thermometer with transparent tape.
2. Choose two objects whose temperature you suspect are different and seem convenient to measure. Assign different values (fixed points) to the temperatures of these two objects and use your marking pen to mark these two points on the tape.
3. Use a ruler to make a rough temperature scale.
4. On your scale, determine the room temperature, ice water temperature, and your body temperature (arm pit). Also read of the Celsius scale.
Your temperature scale / Degree CelsiusRoom
Ice water
Arm pit
Post Questions
1. Are the fixed points reliable, i. e. are they truly fixed?
2. If given more time and better apparatus, could you have chosen more reliable ones? Explain and give an example of a more reliable fixed point.
3. When the thermometer is in thermal contact with the three objects, argue in each case the direction of heat transfer.
Syllabus questions
1. State the relation between the Kelvin and the Celsius scales of temperature in word.
2. How would you in general terms explain how a temperature scale is defined?
A.2 Relative accuracy of thermometers
Aim
Determine the relative accuracy of two thermometers.
Group size
Three
Equipment needed
CBL2
Temperatue probe
Glass thermometer
Two containers for ice water and hot tap water
Stop watch
Cleaning paper
Pre Questions
1. When someone pops a room temperature thermometer in your mouth to see if you have a fever, can the temperature be determined immediately?
2. Suppose you want to measure room temperature with a thermometer that has been in ice water. Which do you predict would cause more time delay – measuring room temperature water or room temperature air? Explain the reason for your prediction.
Procedure
1. Use the CBL temperature probe to verify your prediction using a time graph. NB! Make sure that the temperature probes after leaving the ice water is made dry by removing remaining water drops with some cleaning paper.
2. Sketch the two time graphs.
Post Questions
1. On the bases of these measurements, what should you watch out for in making temperature measurements?
2. The temperature difference between room temperature and ice water is about 20°C. What do you think will happen to the measured time delays if the temperature of the sensor is only two degrees below room temperature?
A.3 Thermal equilibrium
Aim
The aim is to use the concept of thermal equilibrium to explain some effects.
Group size
Two
Equipment needed
Glass thermometer
Clay or cleaning paper
Styrofoam with hole
Metal with hole
Procedure
1. Feel the clay/cleaning paper, the Styrofoam and the metal. Predict which object actually has the highest and lowest temperature.
2. Use the thermometer to find the actually values
Metal / (°C)Clay or cleaning paper / (°C)
Styrofoam / (°C)
Post Questions
1. Did your observation jibe with your prediction? Is your sense of touch an accurate predictor of relative temperatures?
2 Should the temperatures near the surface of three different materials sitting around in the same room be the same or different?
3. Why do some objects feel colder than others?
A.4 Heat transfer
Aim
The aim of this activity is to describe qualitatively the three main processes of heat transfer.
Syllabus reference
3.1.7 and 3.1.8
Group size
Two
Equipment needed
A long and a short piece of iron nail
A candle
Your hand
Procedure
1. Light the candle
2. Move your flat hand towards the flame from above. Notice how near you may put your hand before it hurts.
3. Move your flat hand towards the flame from the side. Notice again how near you may put your hand before it hurts. Compare with the distance under part 2
4. Put one end of the metal pieces simultaneous in the flame. Notice which of these pieces you have to drop first.
Post Questions
1. Identify the procedure steps that correspond to conduction, radiation and convection
2. Based on the results in 2 and 3, it is possible to state the relative significance of two processes of heat transfer. Explain.
A.5 Heat and internal energy
Aim
Review the theoretical ideas behind the concepts of heat and internal energy.
Group size
Two or three
Syllabus reference
3.1.1, 3.1.4, 3.1.5, and 3.1.6
Equipment needed
A sheet of paper, pencil and a good understanding
Procedure
Based on what you have done so far in thermal physics by experiments and theory sessions, answer these questions:
1. What is the difference between a macroscopic and a microscopic view of matter? Use examples!
2. Give the microscopic meaning of temperature, i. e. what is it a measure of?
3. Give also the microscopic meaning of internal energy.
4. How can we understand the concept of heat microscopically?
5. Define the concepts of temperature, internal energy, and heat macroscopically.
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