Melting Ice Cubes
aka. Thermodynamics and Heat Transfer
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Miracle Thaw
 Is
it really a miracle?
 Let’s check it out…
2
Melting Ice Cubes: “Icebreaker” J
First experiment objective:
Determine how fast each different test
material melts an ice cube AND how the
melting of the ice cube effects the test
material’s temperature.
 Establish
teams and have them create a
company name
 Run first experiment
3
Experiment Worksheet
4
 What
is the room temperature?
 Measure and record the temperature of each
material.
 Measure the weight of the material being tested.
– 5th grade: Convert the weight from pounds to kilograms
– 6th grade: Calculate the mass of the material and
compare it to the actual measurement.
– High school: Compare methods for calculating mass
and converting units. I.e., by hand, calculator,
spreadsheet, draw 3-dimensionally on a CAD system
and measure the properties, web
(http://n93.cs.fiu.edu/measures/fulltable.asp), etc.
5
 Calculate
the area of the ice cube.
– Discuss:
» What shape is the ice cube?
» What is the formula for this shape?
» What measurements will be needed?
» How can the necessary measurements be found?
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Calculate Area
 Trace
A  1[rl c(r h)]
2
ice cube
 Measure
chord length: c =
 Measure height: h =
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Calculate Area
A  1[rl c(r h)]
2
 Discuss
the best way to locate the following
measurements:
– Measure angle: α =
– Measure the radius: r =
 Calculate
l
l 001745
.
r
8
To Locate Center of Circle
 Rotate
ice cube, overlapping the curved
portion of the ice cube, and trace it again.
 Fold
the circle in quarters to locate center
or use a compass.
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 Area
answers.
– Give your results to your teacher.
– Break into small groups and compare answers.
– Come up with one answer per group.
 Compare
group answers.
 Using the initial readings, calculate the average.
 Compare the average to the group answers.
 The teacher will use this answer to calculate the
volume of the ice cube.
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 Place
the ice cube, side down, on the material.
 Time from the placement to completely melted.
 Students discuss:
–
–
–
–
Why is the ice cube melting?
What is happening?
How is it changing form?
Where does the heat come from?
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 Record:
– the finish time
– temperature at the center of the puddle
– outside edge of the plate
 Share
data with other groups.
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Summary of First Experiment
Where did the heat come from to melt each
ice cube (from the test material or from the
surrounding air) ?
 What makes one test material faster at
melting the ice cube than another ?
 Why did the ice cubes move ?

 Level
of answers will depend on grade
level.
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Thermodynamics
 Greek
words describe early forms of
thermodynamics
– Therme (heat)
– Dynamics (power)
 Today
it covers a wider spectrum of energy
and energy transformation
– I.e., space shuttle to refrigeration
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Thermodynamics
 Is
the interaction between energy and matter and it
is everywhere
– Hair dryers and heat guns, irons, furnace, air
conditioners, hot water tanks, etc.
– Also must be considered when designing computers,
automobile engines, VCRs, CD players, dimmer
switches, etc.
 What
happens if
– a hair dryer gets too hot?
– a computer gets too hot?
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5th Grade
DT (Delta Time - change in
temperature of the material being tested.)
 Calculate
– (Tfinal - Tinitial)
student DT results to calculated
DT, supplied by the teacher, in a line graph
on graph paper or using a spreadsheet.
 Compare
– Discuss the results
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5th Grade con’t.
 Compare
the amount of heat (Q) each material has
available to the amount of heat required to melt
the ice cube in a combination bar/line graph.
(Data supplied by the teacher)
– Which material(s) did not have enough heat available
to melt the ice cube?
– What can be done to increase the available heat?

Do you see any correlations between the two
graphs?
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Summary
What
test material was the best at
melting ice cubes ?
Did the color seem to effect the
performance ?
Why would an ice cube melt, even if
the test material did not have enough
energy to do it ?
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Thermodynamics
 Therefore,
different materials are used to
the transfer heat
» I.e., the material in the computer chip in the electric
radio alarm clock is used to help keep the chip from
overheating.
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Miracle Thaw
 Is
it really a miracle?
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Suggestions for Higher Grades
5th grade level mathematics, graphs,
etc., only have the students calculate:
 Complete
– The volume and mass of the ice cube.
– The amount of heat generated by each material.
– How long a specific material will take to melt an ice
cube.
Calculate the volume and mass of the material
being tested, and compared to actual measured
weight.
 Discuss heat transfer in more depth.

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Suggestions for Higher Grades con’t.
 Create
an interactive animated computer
program that demonstrates the experiment.
– Example:
– http://socrates.berkeley.edu:7009/simple_machines/
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Additional Exercises




Compare the same material with different masses.
Compare different materials with the same mass.
Conduct a web search of items that use heat sinks.
Examples:
–
Library of Thermodynamics Arizona State Univ.
»
–
Heating system (heat pipe sinks) and fans
»
–
http://www.kita.or.kr/catalog/cheil/index.html
Laptops
»
–
http://www.asu.edu/lib/noble/physics/thermo.htm
http://www.indek.com/heatpipe/hp_app.htm
Computers
»
»
http://www.thermalloy.com/catalog/htm/dhs57.htm
http://www.web_tronics.com/webtronics/heatredmouns.html
–
–
http://www.heatsink.com/
http://www.execpc.com/industrialelectronics/wakefld/wakepg19.html
–
http://www.marlow.com/d_heat.htm
–
Dimmer
»
–
http://home.swbell.net/evansjim/MyHomeRepair/DimmerSwitch.htm
http://www.thermalloy.com/catalog/htm/eprof41b.htm
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Have Fun
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Additional slides for advanced
grades
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THERMODYNAMICS
The science of energy (or its
ability to cause changes), and
 The relationships among the
properties of matter.
 HEAT, Q, is the form of energy
which melted our ice cubes.

 In the SI system, we measure Q in Joules.
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THERMODYNAMICS
Some important material properties:
 m is the mass of the material (kg)
 V is the volume (m3)
 r is the density (kg/m3)
 C is the specific heat (J/kg-oC)
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Some Material Properties
Material
Density
3
(kg/m )
Specific
Heat
o
(J/kg- C)
Thermal
Conductivity
o
(W/m- C)
Steel
Iron
Aluminum
Copper
Lead
Pyrex Glass
Brick
Pine Wood
Plywood
o
Ice (near 0 C)
o
Water (near 0 C)
7,850
7,870
2,770
8,930
11,340
2,225
1,920
640
545
920
1,000
434
447
875
385
129
835
835
2,805
1,215
2,040
4,230
60
73
177
401
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1.4
0.72
0.15
0.12
1.88
0.57
Latent Heat of Fusion for Solid/Liquid Water: 333,700 J/kg
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THERMODYNAMICS
 For a solid, Q = m C DT
This is the amount of heat corresponding
to a change in temperature
 If you don’t know the mass, calculate it
from: m = r V
 DT is the change in temperature,
(Tfinal - Tinitial)

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How much heat does it take to
melt one of our ice cubes ?
If the ice cube is at 0oC,
“Latent Heat of Fusion” (amount of
energy needed to go from solid to
liquid states.
 For water, that is 333,700 Joules/kg.
 If our ice cube is 0.01 kg, the heat
required is 3,337 Joules.

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Do we have enough energy in our
test materials to do that ?
Example:
0.5 kg. chunk of steel, starting at 22oC,
releases 3255 Joules of heat when it is cooled
to 7oC.
 Q = m C DT
= (0.5 kg)(434 Joules/kg-oC)(22-7 oC)
= 3255 Joules
 3337 Joules is needed, therefore, there isn’t
enough heat to melt the ice cube
A
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Conservation of Energy
Better yet, we can solve for the final
temperature of the steel to melt the ice:
Q
D  

mC
3337 Joules
 15.38 o C
Joules
(0.5 kg)(434
)
o
kg  C
Tfinal  Tinitial  D T  22  15.38 C  6.62 C
o
o
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Conservation of Energy
A 0.5 kg block of steel
 Cools from room temperature
(22oC) to 6.62oC
 Gives up enough heat to melt a
0.01 kg ice cube.

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Heat Transfer
– is the flow of energy which happens when
a difference in temperature exists.
– can happen between two bodies or even
within a single body.

What was the difference in temperature
between our ice cubes and our test
materials ?
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CONDUCTION
Heat flows through a material
from molecule-to-molecule.
 Fourier’s Law:

DT
Q  kA
Dx
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Fourier’s Law
DT
Q  kA
Dx
Q is the heat transfer rate
 k is a material property, thermal
conductivity
 A is the area which heat flows through
 DT is the temperature difference
 Dx is the distance the heat must travel

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Fourier’s Law
DT
Q  kA
Dx
How do you make the ice cubes
melt faster ?
What do the terms in Fourier’s
Law show us ?
Which variables can you control ?
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Fourier’s Law
DT
Q  kA
Dx
Fourier’s Law tells us how fast
heat will flow.
 Do we know if there is enough
energy available in our test
materials to melt our ice cube ?

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Fourier’s Law
DT
The rate of heat flow is: Q  k A D x
 The steel block cools from 22oC to 6.62oC
in melting the ice which is 0oC.
 As that happens, the value of DT decreases.
 Therefore, the rate of heat transfer to the ice
decreases.
 How can we increase the rate for a given
material ?
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GO TO WORK !!!
Determine:
if your test materials have
enough heat to melt an ice cube.
Measure the rate (time) of heat transfer.
Tabulate your experiment data.
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