Interactive
Lecture Demonstrations
Prediction Sheet—
Introduction to Heat & Temperature
Directions: Click here to download the Prediction
sheet on which you will record your predictions. This sheet will be
collected. Write your name at the top
to record your participation in these demonstrations. For each demonstration, write your
predictions on this sheet before making any observations. You may be
asked to send this sheet to your instructor.
|
Demonstration 1: A small piece
of metal has been raised to a high temperature, around 80-90°C. Sketch on the right your prediction for the
temperature-time graph for the piece of metal cooling in the room air. Be sure to carefully sketch the shape of
the curve. What do you think the final temperature
of the metal will be? Zero degrees
C? Room temperature? Something different? Only after you have made your
predictions, click here to download the video
and view the experiment. Compare the result to your predictions
and explain any differences. What does it appear that the final
temperature of the metal will be? Explain. |
|
|
|
Demonstration
2: Now the same piece of metal at a high
temperature (around 80-90°C)) is immersed in an insulated cup filled with
cool water (around 20°C). Sketch on the right your predictions for the
temperature-time graphs of the piece of metal and the water in the cup. Be sure to carefully sketch the shapes of
the curves. What
do you think the final temperature of the metal will be? (Zero degrees C? Midway between the initial temperatures of
the water and the metal? Closer to the
initial water temperature? Closer to
the initial metal temperature? Other?) What
do you think the final temperature of the water in the cup will be? Only after you have made your
predictions, click here to download the video
and view the experiment. Compare the results to your predictions
and explain any differences. Compare the results to Demonstration 1
and explain any differences. What does it appear that the final
temperature of the metal will be? The water Explain. |
|
|
|
Demonstration
3: Now a small film container filled with
water at a high temperature (around 80-90°C) is immersed in an insulated cup
filled with room temperature water (around 20°C). Sketch on the right your
predictions for the temperature-time graphs of the film container of hot
water and the water in the cup. Be
sure to carefully sketch the shapes of the curves. How do you think these graphs will
compare to those in Demonstration 2? What
do you think the final temperature of the water in the film container will
be? (Zero degrees C? Midway between the initial temperatures of
the water in the film container and water in the cup? Closer to the initial film container water
temperature? Closer to the initial cup
water temperature? Other?) What
do you think the final temperature of the water in the cup will be? Only after you have made your
predictions, click here to download the video
and view the experiment. Compare the results to your predictions
and explain any differences. Compare the results to Demonstration 2
and explain any differences. What does it appear that the final
temperature of the water in the cannister will be? The water? How is this
different from Demonstration 2? Explain why. |
|
|
|
Demonstration 4: Heat is transferred to water in a perfectly
insulated cup (no heat can leak in or out) at a steady rate for 80 seconds, and
then no more heat is transferred.
Sketch on the right your prediction for the graph of the temperature
of the water as a function of time. Only after you have made your
prediction, click here to download the video
and view the experiment. (Note that each on the graph represents an
equal quantity of heat transferred by a heating coil immersed in the water.) Compare the results to your predictions
and explain any differences. What is the mathematical relationship
between the quantity of heat transferred to a substance and the change in
temperature? |
|
|
|
Demonstration
5: In Demonstration 1 you saw that a hot piece
of metal cooled down in the room air.
Hot water would do the same in an uninsulated cup. If you had a heating coil like in
Demonstration 4 and wanted to keep some water in an uninsulated cup at about
80°C for 100 seconds in a room where the temperature is 20°C, what would you
need to do? Explain, and sketch on the right how the graph would look. Only after you have made your
predictions, click here to download the video
and view the experiment. (Note that each ^ on the graph
represents an equal quantity of heat transferred by the heating coil immersed
in the water.) Compare the results to your predictions
and explain any differences. Why does then temperature remain more or
less constant in this demonstration, while it increases in Demonstration 4?
How is it possible to transfer heat without an increase in temperature? |
|
|
