1766398
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Test por vburke59696, actualizado hace más de 1 año
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Creado por vburke59696
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Pregunta 1
Pregunta
The International System of Units, SI Units, or metrics units of: length, mass, and time are:
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m, kg, min
-
m, kg, h
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ft, slug, s
-
m, kg, s
-
cm, g, s
Pregunta 2
Pregunta
The power in SI-Unit is measured in Watt, that is related to energy by being equal to
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-
energy times time
-
energy consumed
-
energy wasted
-
energy times distance
-
energy per unit time
Pregunta 3
Pregunta
The energy source most used in the United States is
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-
coal
-
water
-
natural gas
-
oil
-
biomass (wood)
Pregunta 4
Pregunta
The two factors that influence energy consumption are:
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supply and demand
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resource and price
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cost and production
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lifestyle and efficiency
Pregunta 5
Pregunta
If you started with a $1,600 investment and you had $12,800 after 6 years, what would be the annual interest rate you received?
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14%
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15%
-
35%
-
19%
Pregunta 6
Pregunta
What is the amount of power in kilowatts consumed per capita in the United States?
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2 kW
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3 kW
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12 kW
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5 kW
Pregunta 7
Pregunta
Running a clothes dryer for 90 minutes (1.5 hours) at 1600 Watts will cost about ____ cents if the cost of electricity is 10 cents per kWh:
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4 cents
-
10 cents
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50 cents
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24 cents
Pregunta 8
Pregunta
The growth rate of GDP of a certain country is 3.5% per year. This means that the GDP is doubling every ____
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2 years
-
10 years
-
5 years
-
20 years
Pregunta 9
Pregunta
A simple machine, such as a set of pulleys and ropes, known as block and tackle, are devices or tools that multiply applied-force, and changes its direction, at the expense of:
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speed
-
velocity
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distance
-
acceleration
Pregunta 10
Pregunta
The following statement is describing which of the three Newton's Laws of Motion? When no-net force is acting is acting on an object, if it is at rest it remains at rest, or if it is in motion, it can only move at a constant velocity.
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First law
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Second law
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Third law
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Law of gravity
Pregunta 11
Pregunta
According to Newton's second law of motion, when a net-force acts on an object, the object must be ____
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accelerating
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going at a constant speed
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moving at constant velocity
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at rest
Pregunta 12
Pregunta
According to Newtons third law, if the push that the car tires give to the road-surface is the action force, the the reaction force is
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the weight of the car
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the force of the car upon the tires
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the friction force of the road-surface on the tires
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the acceleration of the car
Pregunta 13
Pregunta
If a 60 kg person is observed to accelerate at the rate of 4 m/s(^2), the net force responsible for this is
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240 N
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100 N
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120 N
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140 N
Pregunta 14
Pregunta
A car having an initial speed of 9 m/s starts to accelerate at the rate of 4 m/s(^2), the final speed after 5.5 seconds is
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25 m/s
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15 m/s
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19 m/s
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31 m/s
Pregunta 15
Pregunta
A car is moving at 22 m/s (50 mph), when driver sees the traffic light turning red and immediately applies the brakes, decelerating at 6 m/s(^2). What is the car's stopping distance, neglecting the driver's reaction times?
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30.4 m
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10.2 m
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20.3 m
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40.3 m
Pregunta 16
Pregunta
If a stone is dropped from a bridge that is 133 m above the water, how long will it take until the stone hits the water?
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1.7 s
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5.2 s
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3.1 s
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6.2 s
Pregunta 17
Pregunta
A ball is projected straight downward with an initial speed of 20 m/s. After 3 seconds, about how fast is it going?
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30 m/s
-
45.4 m/s
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49.4 m/s
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60.5 m/s
Pregunta 18
Pregunta
A ball is projected straight up at an initial speed of 24.5 m/s. After 2.5 seconds, what is it's speed?
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9.8 m/s
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14.7 m/s
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4.9 m/s
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0 m/s
Pregunta 19
Pregunta
How much work is required to increase the velocity of a 4 kg car from rest to 5 m/s?
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100 J
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200 J
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20 J
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50 J
Pregunta 20
Pregunta
The gravitational potential energy of an object, near the Earth's surface, and the work done to lift the object to the height "h" is given by
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weight times height
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mass times height
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mass times speed
-
mass times acceleration
Pregunta 21
Pregunta
From work-KE theorem, what is the speed of a car of mass 2500 kg, after it is pushed by a force of 500 N over a horizontal distance of 10 m?
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-
1 m/s
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4 m/s
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2 m/s
-
3 m/s
Pregunta 22
Pregunta
When a car is braked to a stop, it's kinetic energy is transformed into
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-
stopping energy
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energy of motion
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potential energy
-
heat energy
Pregunta 23
Pregunta
Our nose cracker moved back and forth as shown. The kinetic energy will be greatest at what point?
(A -> B -> C)
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A
-
B
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A and C
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halfway between A and B
Pregunta 24
Pregunta
The efficiency of a lightbulb is the ratio of the
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energy input to the energy out of the bulb
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light output of the bulb to the electrical energy input
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heat energy out to the electrical energy in
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voltage output of the bulb to the power input
Pregunta 25
Pregunta
If the energy conversion efficiencies in a 3 step process are 36% for the first step, 44% for the second, and 26% for the third, the overall efficiency is about:
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4%
-
9%
-
0.4%
-
2%
Pregunta 26
Pregunta
For a fossil fueled electrical generating plant, 10,000 Btus of chemical energy input into the plant will result in about how many Btus of waste heat dumped into the environment if the efficiency of power plant is 35%?
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8,800 Btus
-
10,000 Btus
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4,080 Btus
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6,500 Btus
Pregunta 27
Pregunta
The first law of thermodynamics states that: heat added to the system, plus work done on the system, equals change in the total energy of the system. This statement is based on-
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how heat can be conducted
-
how temperature is increased
-
the principle of conservation of energy
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the state of the system
Pregunta 28
Pregunta
The second law of thermodynamics states that heat energy flows in the direction of
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-
up, since heat rises
-
higher temperature
-
lower temperature
-
lower entropy
Pregunta 29
Pregunta
The total R-value of a wall made of different layers of materials is obtained by
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-
multiplying the R values of each layer
-
the sum of R values for each layer
-
sum of areas of each layer
-
sum of thicknesses of each layer
Pregunta 30
Pregunta
When ice crystals form in the clouds,
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-
phase change from solid to liquid occurs
-
the thermal mass of the atmosphere increases
-
heat energy is released
-
the atmosphere becomes colder
Pregunta 31
Pregunta
The R-value of material is not related to its
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composition
-
area
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thickness
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resistance to heat flow
Pregunta 32
Pregunta
An object with a very high specific heat will
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decrease in temperature very fast if removed from the source
-
lose its heat very fast
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always be water
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take considerably more heat to raise its temperature
Pregunta 33
Pregunta
The efficiency of an electric motor is the ratio of the
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energy into the motor to the energy out of it
-
heat released to rotational energy
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heat plus electricity produced to the electrical input
-
shaft work output to the electrical energy input
Pregunta 34
Pregunta
For a furnace to provide 80,000 Btu/h of thermal energy to a living space, what should the rate of heat supplied by the fuel be if the furnace efficiency is 65%?
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103,000 Btu
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15,300 Btu
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123,000 Btu
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223,000 Btu
Pregunta 35
Pregunta
A heat engine ____
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converts work into heat energy
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can be 100% efficient in the absence of friction
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can have no cold sink
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needs a hot source and a cold sink to be able to work
Pregunta 36
Pregunta
The heat transfer by conduction through an area 10ft x 7ft section of the wall, with R-value of 35 (ft^2-F-h/Btu), with temperature difference between the sides change in temperature equaling 10 degrees farenheit, will be
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10 Btu/h
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35 Btu/h
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15 Btu/h
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20 Btu/h
Pregunta 37
Pregunta
Since the rate of heat transfer by conduction is proportion to the change in temperature, what percent savings in your cooling bill would you expect if you turned the thermostat up from 70 degrees to 74 degrees, and the outside temperature is 95 degrees?
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26%
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46%
-
6%
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16%
Pregunta 38
Pregunta
Thermal radiations are electromagnetic waves and like all EM waves are of the type
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transverse waves
-
longitudinal waves
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surface waves
-
torsional waves
Pregunta 39
Pregunta
Normally the phase changes from vapor to liquid to solid takes place in that order when the heat is
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kept constant
-
pressure is reduced
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added
-
removed
Pregunta 40
Pregunta
85 degrees Fahrenheit is equal to ____ temperature in Kelvin scale
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-
286 K
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308 K
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316 K
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302 K
Pregunta 41
Pregunta
The Carnot efficiency (maximum possible efficiency) of a heat engine operating between 20 degrees C and 2000 degrees C will be about ____. (Note: the temperature must be in Kelvins -> C + 273)
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-
35%
-
100%
-
72%
-
87%
Pregunta 42
Pregunta
A heat pump will have an efficiency of about ____
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-
35%
-
100%
-
200%
-
50%
Pregunta 43
Pregunta
What are the percentages of Infra-Red (IR), Ultra Violet (UV), and Visible Light in the solar radiation at the top of the Earth's atmosphere?
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17% IR, 37% UV, 46% visible
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37% IR, 5% UV, 58% visible
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51% IR, 12% UV, 37% visible
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47% IR, 7% UV, 46% visible
Pregunta 44
Pregunta
The amount of infrared radiation emitted, or absorbed, by an object, apart from the temperature difference with the surroundings, and the surface area, depends also on
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shape
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color, surface texture
-
its type of material
-
density
Pregunta 45
Pregunta
What is the wavelength of the electromagnetic waves emitted by a Satellite-TV, that has typically a frequency of 12 GHz? (GHz= 10^9 Hz)
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-
0.015 m
-
0.025 m
-
0.035 m
-
0.013 m
Pregunta 46
Pregunta
Specific heat of a substance is defined as the
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heat required to increase its temper by one-degree Fahrenheit
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heat required to increase its temperature by one-degree Celsius
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heat required to increase its heat by one joule
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heat required to increase the temperature one one unite mass by one degree
Pregunta 47
Pregunta
How much heat energy is required to increase the temperature of 3 kg of water from room temperature of 20 degrees C to the boiling point 100 degrees C? (Specific heat of water in SI units is C= 4186 J/kg*C)
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20.4 kJ
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50.6 kJ
-
100.5 kJ
-
789.7 kJ
Pregunta 48
Pregunta
What produces the cooling in a refrigerator?
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-
evaporation of Freon outside
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compression on Freon inside
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condensation of Freon
-
evaporation of Freon inside
Pregunta 49
Pregunta
The geothermal heat, that is, the heat from the interior of the earth, can be used to warm or cool a house
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-
in a certain area
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near hot water springs
-
eight feet below the ground everywhere
-
more than 100 feet underground
Pregunta 50
Pregunta
A wall of a typical house is made of six layers with R-values given in (ft^2- F - h/Btu); from interior dead air later (R1= 0.68), 0.5 in sheetrock (R2= 0.45), 5.5 in fiberglass insulation (R3= 19), 0.5 in plywood (R4= 0.63), exterior dead air layer (R5 = 0.68). If temperature difference between outside and inside is 22 degrees F, and the total area of the wall is 360 ft^2 the rate of heat transfer by conduction is ____.
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567.4 Btu/h
-
156.3 Btu/h
-
369.4 Btu/h
-
423.6 Btu/h
Pregunta 51
Pregunta
The Carnot efficiency of a heat engine operating between 21 degrees C and 1200 degrees C will be about
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-
52%
-
78%
-
80%
-
90%
Pregunta 52
Pregunta
Amount of heat and temperature of an object are different because amount of heat depends on the
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temperature difference
-
energy of its molecules
-
size of its molecules
-
amount of substance
Pregunta 53
Pregunta
The first law of thermodynamics is related to the
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-
conservation of energy
-
heat and temperature
-
entropy and temperature
-
heat and work
Pregunta 54
Pregunta
To keep an iced drink cold for the longest time, what color cup would you use?
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red
-
blue
-
white
-
black
Pregunta 55
Pregunta
Suppose it takes 48,000 Btu to heat up the water in a tank. If the heating element has an output of 2,800 W, then how long will it take to heat up the water, assuming no extra heat losses?
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2 h
-
5 h
-
30 mins
-
3 h
Pregunta 56
Pregunta
The existence of the four seasons, in the mid-latitude locations, is due to the
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-
moon-earth interaction
-
variation of the sun-earth distance
-
tilt of rotation axis of the earth by 23.5 degrees
-
variation of the moon-earth distance
Pregunta 57
Pregunta
Heat transfers by all three ways; conduction, convection, and radiation; are directly proportional to the....
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surface temperature
-
surface roughness
-
surface color
-
surface area
Pregunta 58
Pregunta
The optimal angle of tilt, from the horizontal, for a south facing flat-plate solar collector, or photovoltaic cells panel, in a location with the latitude of 50.5 degrees N, for the purpose of solar panels installation is
Respuesta
-
50.5 degrees
-
60.5 degrees
-
20.5 degrees
-
30.5 degrees
Pregunta 59
Pregunta
What is the main advantage of using thermal mass, in the form of thick concrete floor, or Trombe wall, in a direct-gain passive solar system?
Respuesta
-
to increase temperature fluctuations during the night
-
to provide foundation support for the collector superstructure
-
to increase the insolation on south-facing windows
-
to reduce temperature fluctuations during the day
Pregunta 60
Pregunta
During what season will more insolation be delivered to a vertical south-facing window on a clear day?
Respuesta
-
fall
-
winter
-
spring
-
summer
Pregunta 61
Pregunta
The insolation in a certain location is 900 W/m^2 and 85% of this is direct component on the collector. If a useful rate of energy needed for cooking is 150 W, then what area of the solar collector oven in the form of parabolic mirror is needed to intercept this amount of radiation, take the efficiency to 20%?
Respuesta
-
0.98 m^2
-
1.2 m^2
-
1.6 m^2
-
0.87 m^2
Pregunta 62
Pregunta
Determine the collector area needed to heat 554 lbs of water (80 gallons), in one day, from 50 degrees F to 130 degrees F, if the insolation is 1700 Btu/d/ft^2 and the FPC efficiency is 48%.
Respuesta
-
54 ft^2
-
62 ft^2
-
73 ft^2
-
33 ft^2
Pregunta 63
Pregunta
The main difference between transverse and longitudinal waves is that transverse waves
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-
travel faster than longitudinal waves
-
are not shear waves
-
can not be polarized
-
can be polarized
Pregunta 64
Pregunta
A typical microwave generates the electromagnetic waves of frequency 2.45 GHz (1 Giga= 10^9). The wavelength of the radio wave corresponding to the frequency is
Respuesta
-
9.26 cm
-
8.48 cm
-
11.45 cm
-
12.24 cm
Pregunta 65
Pregunta
In prospection for ore by gravimetric method, (to measure the variation of g=9.8 m/s^2 on the earths surface at a fixed height) how do you distinguish between petroleum and ore?
Respuesta
-
g would be greater over an ore deposit than a petroleum deposit
-
density of ore is less than petroleum
-
g does not change over the surface of the earth
-
g would be greater over a petroleum deposit than an ore deposit
Pregunta 66
Pregunta
When seismic waves (or light waves) travel from one medium into another medium with different wave-speed, what is the difference between reflection and refraction, at the interface between the two media?
Respuesta
-
Refracted wave bends and goes through the second medium
-
reflection and refraction are the same effect
-
reflection can only occur on a smooth interface
-
refraction will not bend the direction of the waves
Pregunta 67
Pregunta
What is the main difference between electromagnetic waves and sound waves?
Respuesta
-
electromagnetic waves can travel in a vacuum
-
sound waves travel faster
-
sound waves can be polarized
-
sound waves can travel in a vacuum
Pregunta 68
Pregunta
The magnitude of gravitational attraction between a 135 kg-person and a 290,000 kg-door of a bunker, with 0.2 m distance between their centers of mass is ____. (G= 6.674 x 10^-11 n*m2/kg2)
Respuesta
-
6.53 x 10^-2 N
-
7.64 x 10^-3
-
8.75 x 10^-3
-
5.42 x 10^-2
Pregunta 69
Pregunta
In a fractionating tower of an oil-refinery, where crude oil is heated from the bottom to separate different hydrocarbon constituents, what is the least volatile constituent of crude oil? That is, the component with the highest boiling point?
Respuesta
-
industrial fuel oil
-
kerosene
-
gasoline
-
asphalt
Pregunta 70
Pregunta
The longevity of a fossil-fuel reserve is determined by the ratio of
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-
proven reserves/ daily production production rate
-
proven reserves / yearly production rate
-
indicated reserves / yearly production rate
-
inferred reserves yearly production rate
Pregunta 71
Pregunta
Pressure on a surface inside a fluid is due to the
Respuesta
-
force of gravity
-
rotational energy of fluid molecules
-
surface tension
-
continuous knocking of fluid molecules on the surface
Pregunta 72
Pregunta
Static pressure at a depth h below the surface of a fluid is given by
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-
mass x g x h
-
density x g x h
-
force x time x h
-
h x g x volume
Pregunta 73
Pregunta
A swimming pool has a depth of 2.5 m. What is the gauge pressure at the bottom of this pool, in psi? (Density of water is pw= 1000 kg/m3)
Respuesta
-
3.553 psi
-
4.652 psi
-
7.324 psi
-
1.334 psi
Pregunta 74
Pregunta
The normal blood pressure is expressed as 80 to 120 mm-of-mercury, which are gauge pressure values. When these values are converted into psi they become ____
Respuesta
-
1.432, 2.133 psi
-
1.547, 2.320 psi
-
1.652, 2.358 psi
-
1.321, 2.142 psi
Pregunta 75
Pregunta
A balloon in the air is buoyed up by a force equal to the
Respuesta
-
weight of the air it displaces
-
weight of the balloon and its contents
-
mass of air displace
-
density of the surrounding air
Pregunta 76
Pregunta
What is the buoyant force on a 3 ton ship that is floating in the sea?
Respuesta
-
2.5 tons
-
3.0 tons
-
3.5 tons
-
1.5 tons
Pregunta 77
Pregunta
Why do you expect photochemical smog to be a greater problem in a city like Los Angeles than in a heavily industrialized city like Pittsburgh?
Respuesta
-
LA has more automobile traffic
-
LA gets more days with temperature inversion
-
LA is less windy
-
Pittsburg has more desulfurization plants
Pregunta 78
Pregunta
The acidity of rain, or other solutions, is measured by the pH number scale that varies from 0 to 14. What does a pH number represent?
Respuesta
-
10 to the positive power of the hydrogen ion concentration
-
the larger the pH number the stronger the acidity
-
the smaller the pH number the less acidic the solution is
-
10 to the negative power of the hydrogen ion concentration in the solution
Pregunta 79
Pregunta
The pressure exerted on your finger if you hold up a 15 lb box of apples, if the contact surface of your finger is 0.25 in x 0.25 in, would be ____
Respuesta
-
200 psi
-
220 psi
-
240 psi
-
160 psi
Pregunta 80
Pregunta
Suppose it takes 38,500 Btu to heat up water in a tank. If the heating element has an output power of 2,500 W, then how long would it take to heat up the water, assuming no extra heat losses? (1 Btu= 1055 Joules, 1 Watt = 1 Joule per second, 1 hour = 3600 s)
Respuesta
-
55 mins
-
2.5 hours
-
3.5 hours
-
4.5 hours
Pregunta 81
Pregunta
During which season will more insolation be delivered to a vertical south facing window on a clear day?
Respuesta
-
Winter
-
Fall
-
Spring
-
Summer
Pregunta 82
Pregunta
The optimum angle of tilt from the horizontal, for a flat plate solar collector, or panels of photovoltaic cells, both facing South, in a location with a latitude of 50.5 degrees North, for the purpose of solar panel installations is
Respuesta
-
30.5 degrees
-
40.5 degrees
-
50.5 degrees
-
60.5 degrees
Pregunta 83
Pregunta
The measure of the angle of position of the sun from the South direction is called the
Respuesta
-
altitude
-
azimuth
-
declination
-
inclination
Pregunta 84
Pregunta
If the insolation (I) upon a flat plate collector is 890 (Btu/ft2*day), how large must the area A of the collector be to provide (Q/t= 12,400 Btu/hr of thermal energy for one day (24 hours)? Take the collector efficiency to be 57.5% (Note: Btu/h is related to I A and E by Q/t = I*A*E)
Respuesta
-
18 ft2
-
164 ft2
-
376 ft2
-
637 ft2
Pregunta 85
Pregunta
The acidity of rain, or a solution, is measured by the pH number, that varies from 0 to 14, what does a pH number represent?
Respuesta
-
10 to the positive power represent the hydrogen ion concentration per mole
-
the larger the pH the stronger the acidity of the solution
-
10 to the negative power of the hydrogen ion concentration per mole in the solution
-
the smaller the pH the less acidic the solution
Pregunta 86
Pregunta
Pressure on a surface is defined as
Respuesta
-
mass x speed
-
mass x velocity
-
density x volume
-
force per unit area
Pregunta 87
Pregunta
Pressure on a surface inside a fluid is caused by
Respuesta
-
weight of fluid molecules
-
force of gravity
-
potential energy of fluid molecules
-
repeated knocking of the fluid molecules on the surface
Pregunta 88
Pregunta
Static pressure at a depth h in a fluid is given by
Respuesta
-
h x g x volume
-
mass x g x h
-
force x time x h
-
density x g x h
Pregunta 89
Pregunta
Atmospheric pressure, at sea level, is 14.7 psi, the gauge pressure of an automobile tire is 38 psi, the absolute pressure of this tire in Pascal is..... (Note: 1 psi = 6895 Pa)
Respuesta
-
131,100 Pa
-
248,200 Pa
-
353,300 Pa
-
363,400 Pa
Pregunta 90
Pregunta
A balloon in the air is buoyed up by a force equal to the ___
Respuesta
-
density of the surrounding air
-
atmospheric pressure
-
weight of the balloon and its contents
-
weight of the air it displaces
Pregunta 91
Pregunta
Which of the following air pollutants is emitted in about equal amounts by stationary and mobile sources?
Respuesta
-
particulates
-
carbon monoxide
-
nitrogen oxides
-
sulfur dioxides
Pregunta 92
Pregunta
Ozone layer in the stratosphere
Respuesta
-
dissipates within days
-
combines with NO or NO2 to produce smog
-
absorbs infrared light from the sun
-
provides protection from incoming UV solar radiation
Pregunta 93
Pregunta
How much has the global temperature on earth changed over the past 100 years?
Respuesta
-
0.5 degrees C
-
1.0 degrees C
-
1.5 degrees C
-
2.0 degrees C
Pregunta 94
Pregunta
One of the fundamentals of electrostatic is that the force between two unlike charges is
Respuesta
-
repulsive
-
neutralized
-
attractive
-
zero
Pregunta 95
Pregunta
Electricity is transmitted from plower plants at ____ to reduce by Joule heating in the transmission lines, which is about 10%.
Respuesta
-
high currents
-
low resistance
-
high resistance
-
high voltage
Pregunta 96
Pregunta
What quantity is the same for three resistors in a series circuit?
Respuesta
-
power
-
resistance
-
current
-
voltage
Pregunta 97
Pregunta
What quantity is the same for three resistors in a parallel circuit?
Respuesta
-
power
-
resistance
-
current
-
voltage
Pregunta 98
Pregunta
A circuit consists of one lightbulb of resistance of 144 ohms and another lightbulb of 240 ohms that are wired in series to a 120 V wall socket outlet. What is the current through this circuit?
Respuesta
-
0.10 A
-
0.20 A
-
0.30 A
-
0.40 A
Pregunta 99
Pregunta
Two resistors of 144 ohms and 240 ohms are wired in parallel to 120 V wall outlet socket outlet, the current through the 240 ohm resistor will be
Respuesta
-
0.3 A
-
0.4 A
-
0.5 A
-
0.6 A
Pregunta 100
Pregunta
The electrostatic force of attraction between two charges of q1= -35 x 10^-6 C and q2 = +69 x 10^-6 C, separated by a distance of 3 m is ___
Respuesta
-
0.4 N
-
1.21 N
-
2.41 N
-
3.53 N
Pregunta 101
Pregunta
A high temperature superconductor compounds such as YBCO ____
Respuesta
-
provides large magnetic fields at room temperature
-
has no resistance at room temperature
-
has no electrical resistance below its critical temperature
-
generates constant voltage at low temperatures
Pregunta 102
Pregunta
A lightbulb draws a current of 2.5 amps, when connected to a wall outlet of 120 V. What is the resistance of the bulb?
Respuesta
-
50 ohms
-
100 ohms
-
200 ohms
-
300 ohms
Pregunta 103
Pregunta
The resistance of four light bulbs are given below. Which one has the highest wattage?
Respuesta
-
144 ohms
-
192 ohms
-
240 ohms
-
320 ohms
Pregunta 104
Pregunta
How much current is drawn by 3240 W electrical appliance operating at 240 V?
Respuesta
-
11.3 A
-
12.4 A
-
13.5 A
-
14.5 A
Pregunta 105
Pregunta
What is the cost of running your water heater of power rating 2800 W for 2.5 hours per day, for one year or 365 days, if the electricity costs 12 cents per kWh?
Respuesta
-
$95
-
$105
-
$206
-
$307
Pregunta 106
Pregunta
The magnetic field of a bar magnet is similar to that produced by
Respuesta
-
a horse shoe magnet
-
a straight current carrying wire
-
two coils separated by long distance
-
a current carrying solenoid
Pregunta 107
Pregunta
Alternating current has an advantage over direct current because
Respuesta
-
batteries can be displaced in most circuits
-
electrical generators can be made
-
produces no heat loss
-
one can step up, or down, the amount of voltage used
Pregunta 108
Pregunta
A transformer (adaptor) can only operate if
Respuesta
-
the power in equals the power out
-
an alternating current is used
-
the potential difference is large enough
-
we step down the current
Pregunta 109
Pregunta
If the current through a 33 ohm resister and a 57 ohm resistor in series is 5 A, then the total voltage drop across both of these resistors will be
Respuesta
-
110 V
-
120 V
-
340 V
-
450 V
Pregunta 110
Pregunta
What transformer turns-ratio of secondary to primary is required to lower the voltage from 120 V wall socket outlet to 8 V for charging a cell phone?
Respuesta
-
15
-
0.044
-
0.075
-
0.067
Pregunta 111
Pregunta
A bird sitting on a bare high voltage wire is not electrocuted because ____
Respuesta
-
of the high resistance of its body
-
its body is at a low electrical potential compared to the wire
-
the high voltage across its feet produced a small current
-
there is no electrical potential difference across its body because the other wire is out of reach
Pregunta 112
Pregunta
For a photovoltaic cell of 0.5 V and of area 1 cm2, the maximum output power is 135 mW (mW= 10^-3 W). What is the current provided by this cell?
Respuesta
-
0.01 A
-
0.02 A
-
0.23 A
-
0.27 A
Pregunta 113
Pregunta
The site location for a wind turbine is especially important. If the power output goes as the cube of the wind velocity, then which of the following average velocities will give approximately 8 times as much output as 10 mph winds?
Respuesta
-
5 mph
-
10 mph
-
15 mph
-
20 mph
Pregunta 114
Pregunta
If the average wind speed for 24 hours is 16 mph at one site but 13 mph at another site for 12 hours and then 23 mph for 12 hours at another site, how much output can be expected from the first turbine compared to the turbine at the second site?
Respuesta
-
35%
-
46%
-
57%
-
68%
Pregunta 115
Pregunta
A 1000 MW power plant is shut down for one day (24 hours). What is the loss of income from this plant if the selling price were 10 cents/kWh (1 MW=10^6 kW).
Respuesta
-
$180,000
-
$700,000
-
$2,400,000
-
$3,500,000
Pregunta 116
Pregunta
For the following circuit, with all the bulbs identical, what is true for the brightness of the lights?
l -----------l (A)
l l_____
l (B) l l (C)
l _______ l ____ l
Respuesta
-
A = B = C
-
A = 4B = 4C
-
A = .5B = .5C
-
A = B, C = 0
Pregunta 117
Pregunta
The existence of atom was proposed by Democritus (420 BCE) and at the beginning of the 19th century, John Dolton proved that every element has an atom, by the ____
Respuesta
-
law of electrostatics
-
ideal gas law
-
law of definite proportion
-
law of conservation of energy
Pregunta 118
Pregunta
The discovery of atomic nucleus was made by firing fast moving ____ at a thin gold foil
Respuesta
-
alpha particles
-
gamma rays
-
electrons
-
neutrons
Pregunta 119
Pregunta
The isotopes of an element all have the same number of
Respuesta
-
protons
-
electrons
-
positron neutrons
-
nucleons
Pregunta 120
Pregunta
For the same energy, the most penetrating type of radiations are
Respuesta
-
B-particles
-
X-rays
-
a-particles
-
y-rays
Pregunta 121
Pregunta
The half-life of a radioactive nuclide is the time taken for _____
Respuesta
-
half of its neutrons to decay
-
half of its electrons to decay
-
half of its mass to decay
-
half of its nuclei to decay
Pregunta 122
Pregunta
At 9 am on Monday, a radioactive sample contained 80 million nuclei. At 9 am on Saturday, 2.5 million of these nuclei are left over and has not decayed. The half life of the sample is
Respuesta
-
1.5 days
-
1 day
-
5 days
-
4 days
Pregunta 123
Pregunta
The radioactive isotope Cobalt-60 decays into Nickel-60 by beta emission, with a half life of 5.3 years. If we start with 100 gram of Co-60, after how many years will we have only 390 milligrams of it left?
Respuesta
-
20
-
42
-
89
-
6
Pregunta 124
Pregunta
The activity of Carbon-14 in the living organism today is 15.3 disintegrations per minute, per gram. Half-life of Carbon-14 is 5730 years. If the activity of an archaeological sample, due to the carbon-14 is 3.825 disintegrations per min, per gram, how old is the sample?
Respuesta
-
2865
-
5730
-
11460
-
22920
Pregunta 125
Pregunta
The binding energy of a Helium nucleus is 4.5 x 10^-12 Joules (28.4 MeV). What is the total binding energy of 4-grams (one mol.) of Helium that has avogadro's number NA= 6.02 x 10^23 of nuclei, when this mass is converted into radiant energy in the interior of the Sun?
Respuesta
-
1.7 x 10^11 J
-
2.7 x 10^12 J
-
1.2 x 10^10 J
-
3.4 x 10^13 J
Pregunta 126
Pregunta
The pair production and annihilation refer to the simultaneous production of a particle and its anti-particle by two energetic gamma-ray photons, near a nucleus, and the destruction of a particle and an anti-particle, as a result of collision between them, these particles and anti-particles can be _____
Respuesta
-
electron and positron
-
proton and electron
-
proton and neutron
-
two neutrons
Pregunta 127
Pregunta
In the following fission reaction, the atomic number Z and mass number of nucleus A of the unknown element Y are:
(0/1)n + (92/235)U --> (53/135)I + (Z/A)Y + (0/2)n
Respuesta
-
38, 102
-
39, 99
-
39, 100
-
37, 100
Pregunta 128
Pregunta
If a light-weight stable nucleus has 12 neutrons, the atomic mass is expected to be _____. (1 atomic mass unit = 1.66 x 10^-27 kg).
Respuesta
-
18 amu
-
24 amu
-
36 amu
-
6 amu
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