Q&A Hero

Q: Ethanol is an alcohol-based fuel that is made from the sugars found in corn and barley. Other sources, such as rice, sugar cane, and potato skins, are also used to produce ethanol. a. True b. False

Q: Two types of wind turbines are used to extract the energy from the wind, a vertical axis turbine and a horizontal axis turbine. a. True b. False

Q: A photovoltaic system converts light energy directly into heat. a. True b. False

Q: A direct passive solar system uses large glass areas on the south wall of a building and a thermal mass to collect the solar energy. a. True b. False

Q: Solar energy starts with the sun at an average distance of 93 million miles from earth. The sun is a nuclear fusion reactor, with its surface temperature at approximately 10,000 F (5500 C). a. True b. False

Q: The U.S. natural gas transportation network consists of 1.5 million miles of mainline and secondary pipelines. a. True b. False

Q: The largest source of electric power in the U.S. is a. solar b. natural gas c. nuclear d. coal e. hydroelectric f. wind

Q: In general, efficiency is defined as a. actual output divided by required input. b. required input divided by actual output. c. actual output multiplied by required input. d. actual output minus required input.

Q: One horsepower represents the power required a. to lift an object weighing 220 lbf, a distance of 2.5 ft in 1 second. b. to lift an object weighting 100 lbf a distance of 5.5 ft in 1 second. c. to lift an object weighting 50 lbf a distance of 11 ft in 1 second. d. all of the above

Q: A common unit used in the United States in air-conditioning and refrigeration systems is ton of refrigeration or cooling. One ton of refrigeration represents the capacity of a refrigeration system to freeze a. 1000 lbm of liquid water at 32F into 32F ice in one hour. b. 2000 lbm of liquid water at 32F into 32F ice in 24 hours. c. 1000 lbm of liquid water at 32F into 32F ice in 24 hours. d. 2000 lbm of liquid water at 32F into 32F ice in one hour.

Q: A team is more powerful than an individual because a. the team can do more work than the individual in the same amount of time. b. the team can do the same amount of work as the individual, but in less time. c. the team can do more work than the individual in less time. d. All of the above.

Q: The SI unit for power is a. watts b. joules c. newtons d. horsepower

Q: Power can be described as a. how hard you push. b. how fast you push. c. how far you push. d. how long you push.

Q: The time rate of doing work is called a. energy b. power c. force d. momentum

Q: Power is found by dividing work by what other physical quantity? a. distance b. mass c. force d. time

Q: The law that simply states that energy is conserved is a. the 0th law of thermodynamics. b. the 1st law of thermodynamics. c. the 2nd law of thermodynamics. d. the 3rd law of thermodynamics.

Q: One Btu is a. nearly equal to 1000 J b. much smaller than 1000 J c. much greater than 1000 J d. none of the above

Q: What are the SI units for heat? a. Kelvins b. Celsius c. Joules d. Watts

Q: Thermal energy transfer is called a. temperature difference b. heat difference c. temperature flux d. heat

Q: Thermal energy transfer occurs whenever there exists a temperature difference within an object, or whenever there is a temperature difference between two bodies, or a temperature difference between a body and its surroundings. a. True b. False

Q: In the absence if heat transfer and no work, conservation of mechanical energy states that the total mechanical energy of a system is a. increasing b. constant c. decreasing d. none of the above

Q: In the following equation, what does the x stand for? elastic energy a. deflection of a spring from its unstretched position b. original length of an unstretched spring c. spring force d. total length of a stretched spring

Q: In the following equation, what does the k stand for? elastic energy a. kinetic energy b. spring constant c. modulus of elasticity d. momentum

Q: What is the SI unit for elastic energy? a. Newtons b. Watts c. Kelvins d. Joules

Q: Calculate the energy required to lift an elevator and its occupants with a mass of 1000 kg through a vertical distance of 5 m. a. 5000 J b. 49000 J c. 25000 J d. 2500 J

Q: A stone is dropped from a bridge and allowed to free-fall downward. As it falls a certain distance its gravitational potential energy decreases by1000 J. By how much does the stone's kinetic energy increase? (Neglect air resistance). a. 100 J b. 500 J c. 1000 J d. 2000 J

Q: The change in gravitational potential energy is found by multiplying an object's change in elevation by its a. mass b. weight c. density d. height

Q: A ping pong ball and a bowling ball are moving with the same momentum. Which has the greater kinetic energy? a. The ping pong ball b. The bowling ball

Q: Which of the following requires the most work done by the brakes of a car? a. slowing down from to b. stopping from c. equal amounts of work for both

Q: Which produces the greater change in kinetic energy (assume that all of the work goes into kinetic energy)? a. exerting a 10 N horizontal force through a distance of 5 m b. exerting a horizontal force of 20 N through a distance of 2 m c. exerting a 30 N horizontal force through a distance of 1.5 m d. exerting a horizontal force of 40 N through a distance of 1m

Q: How much kinetic energy does a 200 g soccer ball have while moving at toward your opponents' goal? a. 4 Joules b. 40 Joules c. 80 Joules d. 8 Joules

Q: What is the SI unit for gravitational potential energy? a. Newtons b. Watts c. Kelvins d. Joules

Q: If you were to push a lawn mower with a constant horizontal force of 20 N. How much work do you do while pushing the lawn mower a total distance of 100 m on level ground?

Q: In the U.S. customary system of units, the unit for kinetic energy is a. lbf.ft b. lbf.ft/s c. slugs.ft d. horsepower

Q: What is the SI unit for work? a. Newtons b. Watts c. Kelvins d. Joules

Q: Work is found by multiplying force by what other physical quantity? a. distance b. mass c. power d. time

Q: Power is a derived dimension. a. True b. False

Q: Energy is a fundamental dimension. a. True b. False

Q: An object having a mass m and moving with a speed V has a kinetic energy, which is equal to a. mV b. mV2 c. mV2 d. mV

Q: When work is done on or against an object, it changes the kinetic energy of the object a. True b. False

Q: Mechanical work is performed when a force moves an object through a distance. a. True b. False

Q: According to a light bulb manufacturer, its 75 W CFL floodlight consumes 25 W and produces 1500 lumens. What is the efficacy of the floodlight?

Q: Most indoor fluorescent light fixtures contain two or three 40-watt bulbs each. If a classroom has 15 fluorescent light fixtures, each with three 40-watt bulbs, how much does it cost to leave the lights on for a two-hour class? Assume the electric company charges approximately 10 cents per kilowatt-hour.

Q: In lighting design, a variable called CRI is often used. What does CRI stand for? a. Color Repeatability Index b. Color Rendition Index c. Capacitive-Resistive Index d. none of the above

Q: The ratio of how much light is produced by a lamp (in lumens) to how much energy is consumed by the lamp (in watts) is known as a. efficacy b. efficiency c. illumination cost d. energy cost

Q: A common unit of illumination intensity is called a footcandle and is equal to a. the amount of light one foot away from a candle. b. the amount of light from a one-foot long candle. c. one lumen distributed over an area of 1-square-foot. d. none of the above

Q: the amount of light emitted by a lamp is expressed in lumens. a. True b. False

Q: The distribution of light on a horizontal surface is known as a. luminescence b. luminosity c. illuminescence d. illumination

Q: Some of the factors that engineers consider when selecting a motor for an application are: a. motor type and speed (rpm). b. motor performance and efficiency. c. cost, life expectancy, and noise level. d. maintenance and service requirements. e. all of the above

Q: How many kW-hour is consumed by a TV set that uses 250 watts when it is left on for 4 hours? a. 250 b. 1000 c. 1 d. 0.25

Q: One kilowatt hour represents the amount of power consumed during 1 hour by a device that uses one kilowatt (kW). a. True b. False

Q: Capacitors are used for a. energy storage b. electronic filters c. timing elements d. all of the above

Q: Electrical components that store energy on two oppositely charged electrodes, rather than through a chemical reaction are known as a. batteries b. inductors c. transistors d. capacitors

Q: In certain circuits, if one of the elements fails, that failure prevents the current from flowing through other elements in the circuit; thus the entire circuit fails. This type of circuit is a a. parallel circuit b. series circuit c. none of the above

Q: Electrical resistance is a fundamental dimension. a. True b. False

Q: When it comes to wire size, the larger the gage number the larger the wire diameter. a. True b. False

Q: The ratio of the diameter of No. 1 AWG wire to No. 2 is a. 1.25 b. 1.5 c. 2.0 d. 1.12

Q: A numbering system that describes the size of an electric conductor is AWG. What does AWG stand for? a. American Wire Gage b. Association of Wire Gages c. Atlas of Wire Gages d. All Wire Gages

Q: Ohm's law describes the relationship between voltage, resistance, and current. Which of these is Ohm's law? a. b. c. d.

Q: Some materials exhibit near-zero resistance at very low temperatures. This behavior is called a. infra-resistance b. anti-resistance c. semiconductivity d. superconductivity

Q: The electrical resistance of a material does not vary with temperature. a. True b. False

Q: An electrical circuit refers to the combination of various electrical components that are connected together. a. True b. False

Q: The law that states that at any given time, the sum of the currents entering a node must equal the sum of the currents leaving the node is know as a. Kirchoff's current law b. Kirchoff's voltage law c. Ohm's law d. Coulomb's law

Q: The flow of electric charge that periodically reverses direction that is typically produced by rotating generators is known as a. ac current. b. dc current. c. ac/dc current. d. omni directional current.

Q: The flow of electric charge that occurs in one direction that is typically produced by batteries is known as a. ac current. b. dc current. c. ac/dc current. d. unidirectional current.

Q: In general, there are two ways in which the sun's energy is converted into electricity: a. photovoltaic and photothermal b. photovoltaic and photochemical c. photovoltaic and photosynthetic d. none of the above

Q: Which of the following batteries is an example of a primary cell? a. Nickel-cadmium (NiCd) also known as "nicad" b. Nickel-metal hydride (NiMH) c. Alkaline d. Lead acid

Q: Primary cells are batteries that can be recharged while secondary cells are batteries that cannot be recharged. a. True b. False

Q: In all batteries, electricity is produced by a. light b. heat c. a chemical reaction d. all of the above

Q: Voltage is sometime referred to as emf. What does emf stand for? a. Electromagnetic frequency b. Electromotive frequency c. Electromagnetic force d. Electromotive force

Q: The amount of work required to move charge between two points is represented by a. electric current b. resistance c. voltage d. energy

Q: One coulomb is defined as the amount of charge that passes a point in a wire in 1 second when a current of 1 ampere is flowing through the wire. a. True b. False

Q: The flow of charge will occur when the two bodies are connected by an electrical conductor such as a copper wire. The flow of electric charge is called electric current. a. True b. False

Q: The SI unit for electric current is a. amperes b. electrons per second c. coulombs d. watts

Q: In SI units, the unit of charge is the coulomb (C). a. True b. False

Q: The basic law of electric charges states that unlike charges attract each other while like charges repel. a. True b. False

Q: Which subatomic particle has no charge? a. Proton b. Neutron c. Electron d. Ion

Q: Which subatomic particle has a positive charge? a. Proton b. Neutron c. Electron d. Ion

Q: Which subatomic particle has a negative charge? a. Proton b. Neutron c. Electron d. Ion

Q: Electric current is a fundamental dimension. a. True b. False