Transcript An inventor develops a stationary cycling device by which

An inventor develops a stationary cycling device by which an
individual, while pedaling, can convert all of the energy
expended into heat for warming water. How much mechanical
energy is required to increase the temperature of 300 gm of
water (enough for 1 cup of coffee) from 20°C to 95°C? (1 cal =
4.186 J)
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94,000 Joules
22,000 Joules
5400 Joules
13.9 Joules
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An inventor develops a stationary cycling device by which an
individual, while pedaling, can convert all of the energy
expended into heat for warming water. What minimum power
must be generated if 300 gm water (enough for 1 cup of coffee)
is to be heated in 10 min from 20°C to 95°C? (1 cal = 4.186 J)
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9400 watts
586 watts
160 watts
31 watts
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A falling 500 kg object is attached by a rope through a pulley to
a paddle wheel shaft which is placed in a well-insulated tank
holding 25 kg of water. The object, in being allowed to fall,
causes the paddle wheel to rotate to churn the water. If the
object falls a vertical distance of 100 m at constant speed, what
is the temperature change of the water? (1 Kcalorie = 4186 J
and g = 9.8 m/s2 )
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19600°C
4700°C
4.7°C
0.8°C
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Sea breezes that occur near the shore are
attributed to a difference between land and
water with respect to what property?
1. mass density
2. coefficient of
volume expansion
3. specific heat
4. emissivity
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Which of the following processes of heat
transfer may take place in a vacuum?
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2.
3.
4.
conduction
radiation
convection
None of these
choices are valid
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Which one of the following processes of
heat transfer require the presence of a
fluid?
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2.
3.
4.
conduction
radiation
convection
None of these
choices are valid
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If cooking is done using an aluminum pan over an
electric burner, which of the following will not promote
the rate of heat flow from burner to food?
1. increase pan bottom
thickness
2. increase pan bottom
area
3. increase burner
temperature
4. decrease height of
pan sides
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The first experiment which systematically demonstrated
the equivalence of mechanical energy and heat was
performed by which of the following scientists?
1. Joule
2. Boltzmann
3. Thompson, Count
Rumford
4. Kelvin
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On a sunny day at the beach, the reason the sand gets
so hot and the water stays relatively cool is attributed to
the difference in which property between water and
sand?
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2.
3.
4.
mass density
specific heat
temperature
thermal
conductivity
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The surfaces of a Dewar flask are silvered
for the purpose of minimizing heat
transfer by what process?
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2.
3.
4.
conduction
radiation
convection
vaporization
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The use of fiberglass insulation in the outer
walls of a building is intended to minimize heat
transfer through what process?
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2.
3.
4.
conduction
radiation
convection
vaporization
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A 200 gm mass of metal with a specific heat of 0.30 cal/gm-°C,
initially at 90°C, is placed in a 500 gm calorimeter initially at 20°
C with a specific heat of 0.10 cal/gm-°C. The calorimeter is filled
with 100 gm of water initially at 20°C. Once the combination of
metal, calorimeter and water reach equilibrium, what is the final
temperature?
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70°C
60°C
50°C
40°C
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Heat flow occurs between two bodies in
thermal contact when they differ in what
property?
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2.
3.
4.
mass
specific heat
density
temperature
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If one's hands are being warmed by holding
them to one side of a flame, the predominant
form of heat transfer is what process?
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2.
3.
4.
conduction
radiation
convection
vaporization
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The first experimental observation which tended
to disprove the caloric model of heat was made
by which of the following scientists?
1. Joule
2. Boltzmann
3. Thompson, Count
Rumford
4. Kelvin
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A 20 gm object has what specific heat if
its temperature increases by 5°C when 20
cal of heat are transferred to it?
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2.
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4.
0.20 cal/gm-°C
0.40 cal/gm-°C
0.60 cal/gm-°C
0.85 cal/gm-°C
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In a greenhouse, electromagnetic energy in the form of
visible light enters the glass panes and is absorbed and
then reradiated. What happens to this reradiated
electromagnetic radiation from within the greenhouse?
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2.
3.
4.
100% returns to the
atmosphere
blocked by glass
transformed into
ultraviolet upon striking
the glass
reflected as visible light
upon striking the glass
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Which of the following best describes a substance in
which the temperature remains constant while at the
same time it is experiencing an inward heat flow?
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2.
3.
4.
gas
liquid
solid
substance
undergoing a
change of state
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A copper rod has one of its ends placed in a Bunsen
flame and the other end embedded in an ice cube. By
what factor is the rate of heat flow changed when the
rod length is tripled?
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3.
4.
0.33
1/9
3.0
9.0
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A copper rod has one of its ends placed in a heat reservoir
and the other end in a heat sink. By what factor is the rate
of heat flow changed when the temperature difference
between the reservoir and sink is tripled?
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0.33
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The surface of the sun has a temperature of about 5800
K. If the radius of the sun is 7 x 108 m, determine the
power output of the sun. (Take S = 1, and s = 5.67 x 10-8
W/m2 /K4 )
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3.95 x 1026 W
5.17 x 1027 W
9.62 x 1028 W
6.96 x 1030 W
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The tungsten filament of a lightbulb has an operating
temperature of about 2100 K. If the emitting area of the
filament is 1 cm2 , and its emissivity is 0.68, what is the
power output of the lightbulb? (s = 5.67 x 10-8 W/m2 x K4 )
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100 W
75 W
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40 W
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A 5 - gram lead bullet traveling in 20°C air at 300 m/s strikes a
flat steel plate and stops. What is the final temperature of the
lead bullet? (Assume all heat is retained by the bullet). The
melting point of lead is 327°C. The specific heat of lead is 0.122
J/g/°C. The heat of fusion of lead is 24.7 J/g.
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227°C
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327°C
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A slice of bread contains about 100 kilo-calories. If the
specific heat of a person is 1 kilocalorie/kg x°C, by how
many °C would the temperature of a 70-kg person
increase if all the energy in the bread were converted to
heat?
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2.25°C
1.86°C
1.43°C
1.00°C
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At high noon, the sun delivers 1000 watts to each
square meter of a blacktop road. What is the equilibrium
temperature of the hot asphalt? (s = 5.67 x 10-8 W/m2 /
°K4 )
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75°C
84°C
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99°C
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A silver bar of length 30 cm and cross-sectional area 1 cm2
is used to transfer heat from a 100°C reservoir to a 0°C block
of ice. How much ice is melted per second? (For silver, k =
427 W/m x °C. For ice, Lf = 334,000 J/kg.)
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4.2 grams/s
2.1 grams/s
0.8 grams/s
0.042 grams/s
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Find the final equilibrium temperature when 10 grams of milk at
10°C is added to 160 grams of coffee at 90°C. (Assume the
specific heats of coffee and milk are the same as water and
neglect the heat capacity of the container).
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85.3°C
77.7°C
71.4°C
66.7°C
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How much heat energy is required to vaporize a 1 gram ice cube at 0°C? The heat of fusion of ice is 80
calories/gram. The heat of vaporization of water is 540
cal/gram.
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3.
4.
620 calories
720 calories
820 calories
1 kilocalorie
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How much heat energy must be removed from 100
grams of oxygen at 22°C to liquify it at -183°C? (The
specific heat of oxygen gas is 0.218 cal/g-°C and its
heat of vaporization is 50.9 cal/gram.)
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13,652 cal
9,559 cal
4,316 cal
2,160 cal
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100 grams of liquid nitrogen at 77° K is stirred into a beaker
containing 500 grams of 15°C water. If the nitrogen leaves the
solution as soon as it turns to gas, how much water freezes?
The heat of vaporization of nitrogen is 48 cal/gram. The heat of
fusion of water is 80 cal/gm.
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none
29 grams
68 grams
109 grams
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In winter, light colored clothes will keep
you warmer than dark colored clothes if
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you are warmer than your
surroundings.
you are at the same
temperature as your
surroundings.
you are cooler than your
surroundings.
you are standing in
sunlight.
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45
46
47
48
49
50
I take 1 kg of ice and dump it into 1 kg of water and, when
equilibrium is reached, I have 2 kg of ice. The water was
originally at 0°C. The specific heat of water = 1 kcal/kg-°C, the
specific heat of ice = 0.5 kcal/kg-°C, and the latent heat of
fusion of water is 80 kcal/kg-°C. The original temperature of the
ice was
25% 25% 25% 25%
1.
2.
3.
4.
one or two degrees below 0°C
-80°C
-160°C
the whole experiment is
impossible.
1
2
3
4
5
6
7
8
9
10
11
12
13
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15
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18
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23
24
25
26
27
28
29
30
31
32
133
34
235
36
37
3
38
39
4
40
41
42
43
44
45
46
47
48
49
50
Consider two different rods and predict
which will have the greatest thermal
conductivity. The rod with
1. electrons that are
freer to move from
atom to atom.
2. the greater specific
heat.
3. the greater crosssectional area.
4. the greater length.
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
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30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Which type of heating causes
sunburn?
1.
2.
3.
4.
conduction
convection
radiation
all of these cause
sunburn
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
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32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Carbon dioxide and water molecules
in the atmosphere will absorb
1.
2.
3.
4.
infrared light.
visible light.
ultraviolet light.
radio waves.
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
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15
16
17
18
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20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
In a cloud formation, water vapor turns into water
droplets which get bigger and bigger until it rains. This
will cause the temperature of the air in the clouds to
1. get warmer.
2. get cooler.
3. will not affect the
temperature of the
air in the clouds.
4. there is no air in
clouds.
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
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19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Active solar heating involves
the use of
1. convection
currents.
2. air locks.
3. pumps.
4. the greenhouse
effect.
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
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20
21
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23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A 120-gram block of copper is taken from a kiln and carefully
placed into a beaker containing 300 grams of water. The water
temperature rises from 15°C to 35°C. Given cCu = 0.10
cal/gram-°C, and cwater = 1.00 cal/gram-°C, what was the
temperature of the kiln?
25% 25% 25% 25%
1.
2.
3.
4.
500°C
360°C
720°C
535°C
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
125 grams of dry ice (solid CO2 ) is dropped into a beaker
containing 500 grams of 66°C water. The dry ice converts
directly to gas, leaving the solution. When the dry ice is gone,
the final temperature of the water is 29°C. What is the heat of
vaporization of solid CO2 ?
25% 25% 25% 25%
1.
2.
3.
4.
37 cal/gram
74 cal/gram
111 cal/gram
148 cal/gram
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
1
2
3
4
A piece of copper of mass 100 grams is being drilled through
with a 1/2" electric drill. The drill operates at 40 W and takes 30
seconds to bore through the copper. The specific heat of copper
is 387 J/kg-°C. Find the increase in its temperature.
25% 25% 25% 25%
1.
2.
3.
4.
40.6°C
34.7°C
31.0°C
27.3°C
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
As I use sandpaper on some rusty
metal, the sandpaper gets hot.
1.
2.
3.
4.
Heat is flowing from the
sandpaper into the metal.
Heat is flowing from the
metal into the sandpaper.
Friction is creating the
heat.
Heat is flowing from my
hand into the sandpaper.
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A 50 gm cube of ice, initially at 0°C is dropped into a 200 gm of
water in an 80 gm aluminum container, both initially at 30°C.
What is the final equilibrium temperature? (Specific heat for
aluminum is 0.215 cal/gm-°C and Lf = 80 cal/gm.)
1.
2.
3.
4.
17.9°C
9.4°C
12.1°C
20.6°C
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
If heat is flowing from a table to a block of
ice moving across the table, which of the
following must be true?
1.
2.
3.
4.
The table is rough and there is
friction between the table and
ice.
The ice is cooler than the
table.
The ice is changing phase.
All three are possible, but
none is absolutely necessary.
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A 500 gm ice cube, initially at 0°C, is placed in a styrofoam box
whose wall thickness is 1.0 cm and the total surface area is 600
cm2 . If the air surrounding the box is at 20°C and after 4 hours
the ice is completely melted, what is the conductivity of the
styrofoam material? (Lf = 80 cal/gm)
25% 25% 25% 25%
9.6 x 10-5 cal/cm-sec-°C
2.8 x 10-6 cal/cm-sec-°C
1.15 x 10-2 cal/cm-sec-°C
2.3 x 10-4 cal/cm-sec-°C
1.
2.
3.
4.
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A solar heating system has a 25% conversion efficiency;
the solar radiation incident on the panels is 1000 W/m2.
What is the increase in temperature of 30 kg of water in a
1.0 hr period by a 4.0 m2 area collector?
1.
2.
3.
4.
25% 25% 25% 25%
14.3°C
22.4°C
28.6°C
44.3°C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1
33
34
2
35
36
3
37
38
394
40
41
42
43
44
45
46
47
48
49
50
A 100 gm piece of copper, initially at 95°C, is dropped into 200
gm of water contained in a 280 gm aluminum calorimeter; the
water and calorimeter are initially at 15°C. What is the final
temperature of the system? (specific heats of copper and
aluminum of 0.092 and 0.215 cal/gm-°C, respectively)
25% 25% 25% 25%
1.
2.
3.
4.
16.8°C
18.3°C
23.7°C
25.0°C
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A machine gear consists of 0.1 kg of iron and 0.16 kg of copper.
How much total heat is generated in the part if its temperature
increases by 35°C? (Specific heats of iron and copper are 0.11
and 0.092 kcal/kg/°C, respectively, and 1 kcal = 4186 J.)
25% 25% 25% 25%
1.
2.
3.
4.
910 J
3770 J
3980 J
4420 J
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
What is the temperature increase of 4.0
kg of water when heated by a 800 W
immersion heater for 10 min?
25% 25% 25% 25%
1.
2.
3.
4.
56°C
51°C
28°C
14°C
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Iced tea is made by adding ice to 1.8 kg of hot tea,
initially at 80°C. How many kg of ice, initially at 0°C, are
required to bring the mixture to 10°C? (Lf = 80 kcal/kg)
1.
2.
3.
4.
1.8 kg
1.6 kg
1.4 kg
1.2 kg
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
The filament temperature of a light bulb is 2000 K when
the bulb delivers 40 W of power. If its emissivity remains
constant, what power is delivered if the filament
temperature is raised to 2500 K?
1.
2.
3.
4.
105 W
62 W
98 W
50 W
25% 25% 25% 25%
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A waterfall is 145 m high. What is the increase in
temperature of the water at the bottom of the falls if all
of the initial potential energy goes into heating the
water? (g = 9.8 m/s2 and 1 kcal = 4186 J)
1.
2.
3.
4.
25% 25% 25% 25%
0.16°C
0.34°C
0.69°C
1.04°C
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A 0.2 kg aluminum plate, initially at 20°C, slides down a 15 m long
surface, inclined at a 30° angle to the horizontal. The force of kinetic
friction exactly balances the component of gravity down the plane so
that the plate, once started, glides down at constant velocity. If 90% of
the mechanical energy of the system is absorbed by the aluminum,
what is its temperature increase when at the bottom of the incline?
(Specific heat for aluminum is 0.215 kcal/kg/°C and 1 kcal = 4186 J)
1.
2.
3.
4.
25% 25% 25% 25%
0.16°C
0.08°C
0.04°C
0.03°C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
132
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
2
3
4
How many kilo-watt hours of energy would be required to
raise the temperature of a 30,000 gallon swimming pool by
5°C? (One gallon of water has a mass of approximately 3.8
kg and the specific heat of water is 4186 J/kgx°C.)
25% 25% 25% 25%
1.
2.
3.
4.
1047.7 kWH
662.8 kWH
330.0 kWH
216.6 kWH
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
21
22
23
24
25
26
27
28
29
30
31
32
33 1 34
35
41
42
43
44
45
46
47
48
49
50
2
16
17
36
37
3
18
19
20
38
39
4 40
A solar heated house loses about 5.4 x 107 cal through its outer
surfaces on a typical 24 hr winter day. What mass of storage
rock is needed to provide this amount of heat if it is brought up
to initial temperature of 62°C by the solar collectors and the
house is maintained at 20°C? (Specific heat of rock is 0.21
cal/gm-°C.)
1.
2.
3.
4.
25% 25% 25% 25%
163 kg
1,230 kg
6,100 kg
12,700 kg
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
133
34
235
36
37
3
38
39
4
40
41
42
43
44
45
46
47
48
49
50
A 2-m2 thermopane window is constructed, using two layers of
glass 4 mm thick, separated by an air space of 5 mm. If the
temperature difference is 20° from the inside of the house to the
outside air, what is the rate of heat flow through this window?
(Thermal conductivity for glass is 0.8 J/s x m x °C and for air
0.0234 J/s x m x °C.)
25% 25% 25% 25%
1.
2.
3.
4.
8000 W
2000 W
568 W
179 W
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
1
2
3
4
A 0.003 kg lead bullet is traveling at a speed of 240 m/s when it
embeds in a block of ice at 0°C. If all the heat generated goes
into melting ice, what quantity of ice is melted? (Lf = 80 kcal/kg,
the specific heat of lead = 0.03 kcal/kg °C, and 1 kcal = 4186 J)
25% 25% 25% 25%
1.
2.
3.
4.
1.47 x 10-2 kg
5.8 x 10-4 kg
3.2 x 10-3 kg
2.6 x 10-4 kg
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A flat pan container holds 200 gm of water. If over a 10
min period, 1.5 gm of water evaporates from the
surface, what is the approximate temperature change of
the remaining water? (Lv = 540 cal/gm)
25% 25% 25% 25%
1.
2.
3.
4.
+4°C
-4°C
+0.4°C
-0.4°C
1
2
3
4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
A glass pane 0.4 cm thick has an area of 2 m2 . On a
winter day the temperature difference between the inside
and outside surfaces of the pane is 20°C. What is the rate
of heat flow through this window? (Thermal conductivity for
glass is 0.8 J/s x m x °C.)
25% 25% 25% 25%
1.
2.
3.
4.
32,000 J/s
8,000 J/s
4,000 J/s
1,000 J/s
1
2
3
4
5
6
7
8
9
10
11
12
21
22
23
24
25
26
27
28
29
30
31
32
41
42
43
44
45
46
47
48
49
50
13
14
33
34
1
15
16
17
18
19
20
35
36
37
38
39
40
2
3
4
A 0.003 kg lead bullet is traveling at a speed of 240 m/s when it
embeds in a wood post. If it assumed that half of the resultant
heat energy generated remains with the bullet, what is the
increase in temperature of the embedded bullet? (Specific heat
of lead = 0.03 kcal/kg- °C, 1 kcal = 4186 J.)
25% 25% 25% 25%
1.
2.
3.
4.
115
137
230
259
1
2
3
4
5
6
7
8
9
10
11
12
21
22
23
24
25
26
27
28
29
30
31
32
41
42
43
44
45
46
47
48
49
50
1
13
14
15
16
17
18
19
20
33
34
2 35
36
3 37
38
4 39
40