Download Heat Transfer conduction

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Heat Transfer
Introduction
Heat energy is transferred from a high heat “source” to a low heat “sink”. Heat
energy will “flow” from high temperature areas to low temperature ones through one of
three methods; radiation, convection or conduction. Radiation is a mode of energy
transfer that does not require a medium, or substance to travel through it. Convection is a
flow of energy in gases or liquids. This is where heated substances rise to the top, while
cooler parts sink to the bottom. Conduction is a mode of energy transfer through solids
only. Heat energy within particles of an object are transferred through particle collisions.
Objectives

You will be able to indicate the direction in which energy would be transferrd
between two objects, given there temperatures.

You will be able to identify conditions in which heat is lost or gained, and
determine the amounts and relative rate of heat exchange, given a graph of
temperature vs. time of two equal masses of water that are exchanging energy.
Materials
Calorimeter
Two thermometers
Two Styrofoam cups
Aluminum Bar
100 ml of boiling water
100 ml of room temperature water
Procedure
1. Put boiling water (1000C) in one calorimeter, and room temperature water in
the other.
2. Place the two cups in such a position that one end of the U-shaped aluminum
bar can be inserted into the water in one cup, and the other end of the bar
inserted into the water in the other cup.
3. Place a thermometer in each cup.
4. Record the temperature of each thermometer at 2 minute intervals for 20
minutes.
Minutes
0
2
4
6
8
10
12
14
16
18
20
Boiling Water
Room
Temperature
Conclusion Questions
1. In what direction does the energy flow? What is your evidence?
2. How does the energy lost by the hot calorimeter compare with the energy
gained by the cold calorimeter? Why?
3. How is the energy transferred from the water in one calorimeter to the water
in the other?
4. What could you do to make the final temperature readings in each calorimeter
higher?
5. Is there any heat lost during this experiment? If so, from where and what is
the mode by which it is lost?
6. Explain how energy from the hot water is being transferred from the water,
through the aluminum bar and into the cold water. Explain in terms of
molecules and energy; sources and sinks.
7. What are the three modes of energy transfer on Earth? Define each one.
8. What are the four energy interactions on Earth?