experiment#5 by bayot,lim,uy
TRANSCRIPT
7/28/2019 Experiment#5 by Bayot,Lim,Uy
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De La Salle University
College of Education
Science Education DepartmentPHY 583M – Earth and Environmental Science
Experiment # 5METHODS OF HEAT TRANSFER
PART I HEAT TRANSFER BY CONDUCTIONPART II HEAT TRANSFER BY RADIATION
Members: Bayot, Joysol
Lim, Perlita
Uy, Roxanne
Prof: Dr. Cecil Galvez
Class Period: Sat, 8:00 am – 11:00 am
Date performed: 4/6/13
Date submitted: 4/13/13
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PART I HEAT TRANSFER BY CONDUCTION
I. INTRODUCTION
A. BACKGROUND INFORMATION/THEORY AND CONCEPTS
Thermal energy transfer occurs between two substances, whenever there is a temperaturedifference between them. The process of thermal energy transfer from one substance to
another by direct contact is know and conduction. During this process, thermal energy is
transferred from a warmer substance to a cooler substance. Thermal energy transfer is
dependent on the conductivity of the substance. Thermal conductivity is a measure of
how fast thermal energy moves within a substance.
Solids are the best conductors of heat, and among solids, metals conduct heat the best.
But metals differ in their conductivity-silver is a very good conductor; copper and
aluminium are good conductors; iron and lead are poor conductors.
In this experiment two metals will be tested experimented in order to determine their
thermal conductivity.
B. OBJECTIVES
This activity aims:
To determine how the type of material can affect conductivity of an object.
To determine which type of metal will conduct thermal energy from one end to
the other more rapidly.
C. HYPOTHESIS
Aluminum will conduct thermal energy faster than brass
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II. METHOD
START
SECURE MATERIALS
PREPARE SET-UP
USE DATA STUDIO PROGRAM
ARRANGE SET UP ACCORDING TO THE DIAGRAM
ATTACH USB LINKS TO COMPUTER AND OPEN
DATA STUDIO SOFTWARE
DETERMINE WHICH METAL REPRENTS THE
AUMINUM AND THE BRASS
CLEAR ALL DATA FOR DATA STUDIO
START DATA ATUDIO AND GET INITIAL
TEMPERATURE OF THE METAL ROD
TURN ON THE SOLDERING IRON
A
A
OBSERVE TEMPERATURE CHANGE FOR 15
MINUNTES
IS IT 15
MINUTES N
ALREADY?
Y
STOP RECORDING OF DATA
GET FINAL TEMPERATURE
IS THE DATA
COMPLETE
AND N
ACCURATE?
Y
FIX SET UP
END
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III. Materials Used and experimental set-up
USB Link
2 PASPORT Temperature Sensors Buret clamps Soldering iron
2 different metal rods with the same dimension
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IV. DATA
a. OBSERVATIONS in a DATA TABLE or CHART
metal Starting
Temp.
(0C)
Ending
Temp.
(0C)
Time to
Final temp.
(s)
Slope of
the Line
aluminium 25.1 49.6 900 0.0329
brass 25.5 35.2 900 0.0127
Table 1 .Shows the starting temperature, ending temperature, time to final temperature, and
slope of the line for both aluminium and brass
b. GRAPHS
Figure 1. Temperature against time of aluminium and brass
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Figure 2. Temperature against time of aluminium and brass with linear fit data
c.
CALCULATIONS
m= y2 – y1
x2 – x1
whereinm = slope
y = change in temperature
x= change in time
V. ANALYSIS
Base from table 1, starting temperature is almost the same- 25.10C for aluminum while
25.10C for brass. The ending temperature, however, changed significantly- 49.6
0C for
aluminum while 35.2 for brass. Slope of both metals is also is significant- 0.0329 for
aluminum and brass has 0.0127.
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VI. CONCLUSION
Aluminum heats up faster than brass because it has a higher thermal conductivity value
than brass. Aluminum has a thermal conductivity of 0.57 cal/cm.s.0C while brass has a
thermal conductivity of 0.31 cal/cm.s.0C.
VII. ANSWERS TO QUESTIONS
1. Was your prediction correct?
Yes, aluminium conducts heat faster than brass
2. How do you know the metal cylinders conducted heat energy?
Heat is the byproduct of an object vibrating at the molecular level. When those vibrationstransmit to nearby collision molecules, heat transfer occurs. Generally, the less a metal
weighs, the quicker it can transfer heat.
3. Which metal conducted heat energy the fastest? Explain using the slope dataAluminum conducts heat energy the fastest. It is less dense than brass, so has less mass
per volume to absorb heat energy. For the same amount of heat energy put into the same
volume of aluminum and brass, the aluminum will increase in temperature faster since
there is less mass to heat up. This is also known as thermal inertia. Aluminum has lessthermal inertia than brass. Their slope also defines heat energy transfer. The larger the
slope, the faster it conducts heat energy, in this case aluminum has a slope of 0.0329while brass has only 0.0127.
VIII. REFERENCES
1. Williams, Trinklein, Metcalfe. Modern Physics, 1 st
edition.1984
2. Cordero-Navaza and Valdes. Physics, 2nd
edition. 2001
3. Hewitt. Conceptual Physics. 2005
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PART II HEAT TRANSFER BY RADIATION
I. INTRODUCTION
A. BACKGROUND INFORMATION/THEORY AND CONCEPTS
Radiation (radiant energy) is the transfer of energy by invisible waves given off by theenergy source. Heat from the sun travels through space by radiation. This form of heat,
radiant heat, is thought to be produced by the internal vibration of the particles that make
up a body that is the source of heat (like the sun), and moves through space in the form of
a wave. Radiant heat is only one of the many forms of electromagnetic waves.
Color affects the amount of radiant heat absorbed by an object. Black or darkened
surfaces absorb heat faster than white or light-colored ones.
In this experiment a black painted can’s tem perature change will be compared with an
unpainted can if exposed to the same amount of heat.
B. OBJECTIVES
This activity aims:
To determine how colour effects radiant energy transfer.
To compare temperature change between a painted and an unpainted can by
means of radiation
C. HYPOTHESIS
Painted can will heat up more than the unpainted can
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II. METHOD
START
SECURE MATERIALS
PREPARE SET-UP
USE DATA STUDIO PROGRAM
ARRANGE SET UP –heat lamp is about 20 cm. in
front of the 2 cans
ATTACH USB LINKS TO COMPUTER AND OPEN
DATA STUDIO SOFTWARE
DETERMINE WHICH METAL REPRENTS THE
PAINTED AND THE UNPAINTED CAN
CLEAR ALL DATA FOR DATA STUDIO
START DATA STUDIO AND GET INITIAL
TEMPERATURE OF THE CANS
OBSERVE TEMPERATURE CHANGE FOR 15 MINUNTES
A
A
IS IT 15
MINUTES N
ALREADY?
Y
STOP RECORDING OF DATA
GET FINAL TEMPERATURE
IS THE DATA
COMPLETE
AND N
ACCURATE?
Y
FIX SET UP
END
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III. Materials Used and experimental set-up
USB Link
2 PASPORT Temperature Sensors
2 radiation cans painted black and silver
150 Watts lamp
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IV. DATA
a. OBSERVATIONS in a DATA TABLE or CHART
Painted Can
(0C)
Unpainted Can
(0C)
Starting Temp. 25.8 25.7
Ending Temp. 31.7 27.3
Change in Temp. 5.9 1.6
Table 1.Shows the comparison of absorption of radiation of a painted (black) versus an
unpainted can
b. GRAPHS
Figure 1. Temperature against time of the painted (black) and unpainted (light) can
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Figure 2. Temperature against time of the painted (black) and unpainted (light) can with
linear fit data
c. CALCULATIONS
Change in Temperature = Starting Temperature- Ending Temperature
V. ANALYSIS
Base from table 1 it shows the starting, ending and change in temperature for the painted
and unpainted can. The painted can has almost the same starting temperature of 25.80C
with the unpainted can, which was 25.70C. However Their ending temperature has a
significant change- The painted can’s temperature raised to 31.7 0C while the unpainted
can has only raised to 27.30C. The change in temperature is 5.9 for the painted can while
1.6 only for the unpainted can. This shows that through radiation, the black can absorbed
more heat efficiently.
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VI. CONCLUSION
Dark colored materials will absorb more heat than light colored materials.
VII. ANSWERS TO QUESTIONS
1. Suppose you had to choose a roof color for a new house and were given two choices:
dark grey or light grey. Which would you choose to keep your house cooler in the
summer? Why?
One should choose the light grey color. Light colors reflect heat and sunlight; whereas
dark colors absorb heat and light. Buildings are similar to people. If one has a dark-
colored roof, one’s building will be hotter than if it had a light-colored roof. This sameroof, on a clear, cool night will transmit more heat from the house than would a light
colored roof. A white or nearly white roof will reflect solar radiation during the day andwill not radiate much heat at night.
2. Why does an asphalt parking lot feel hotter in the summer than an adjacent grassy
area?
Asphalt is very "dark" in color. Things that appear dark in color reflect much less visible
light than those that are light. Instead of reflecting all that light, it is absorbed. Being
absorbed means that when the energy from the light strikes the molecules it causes the
atoms to vibrate. This vibration is heat. This heat then radiates to the ambient air around
it, causing it to also be much warmer. Grass is "bright" in color.
Grass has large quantities of water in it, which constantly is being converted and
evaporated. The act of evaporating water requires heat, so it "sucks" the heat out of the
grass. That heat does then go into the surrounding area, but to remain a gas, the water
must hold onto it, and because of it's low density the water vapor rises away from the
ground, both things decreasing the ambient air temperature.
Grass also directly uses the energy provided by the light to break apart and recombine
molecules from water, air and other sources for life and growth. Think of it as "eating"
what is around it. This process is called photosynthesis