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Question About Science |
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| Title: |
Chemistry -Elctronics and Electricity, sound, Mechanics,heat (#35BB) |
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Science |
| Inquirer: |
helpmeplease_21 |
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I need this done if you can help it would be nice. It is an exam that needs to be done but I don't understand it...
This is dealing with electronics and Electricity
1. If one body is positively charged and another body is negatively charged, free electrons tend to
A. move from the negatively charged body to the positively charged body.
B. move from the positively charged body to the negatively charged body.
C. remain in the negatively charged body.
D. remain in the positively charged body.
2. A battery consists of five dry cells connected in series. If the voltage developed by each cell is 1.5 V, the total voltage developed by the battery is
A. 0.3 V.
B. 1.5 V.
C. 5.0 V.
D. 7.5 V.
3. The grid in a high-vacuum triode is usually kept negatively charged with respect to the cathode so that the electrons may be
A. accelerated toward the anode.
B. accelerated toward the cathode.
C. attracted to the anode instead of the grid.
D. attracted to the cathode instead of the grid.
4. An example of an atom that has no charge is one that has
A. 2 protons, 2 electrons, and 1 neutron.
B. 1 proton, 2 electrons, and 3 neutrons.
C. 3 protons, 1 electron, and 3 neutrons.
D. 3 protons, 2 electrons, and 1 neutron.
5. If an electrically uncharged body is contacted by an electrically charged body, the uncharged body will
A. develop the opposite charge as the charged body.
B. remain a neutrally charged body.
C. develop the same charge as the charged body.
D. neutralize the charged body.
6. What bias conditions must be present for the normal operation of a transistor amplifier?
A. The emitter-base junction must be reverse biased, and the collector-base junction must be forward biased.
B. The emitter-base junction must be forward biased, and the collector-base junction must be reverse biased.
C. Both junctions must be reverse biased.
D. Both junctions must be forward biased.
7. When an electric current flows through a long conductor, each free electron moves
A. from one end of the conductor to the other end.
B. with a speed of 300,000,000 m/s.
C. back and forth between the ends of the conductor.
D. through a relatively short distance.
8. If the resistance of an electric circuit is 12 ohms and the voltage in the circuit is 60 V, the current flowing through the circuit is
A. 0.2 A.
B. 5 A.
C. 60 A.
D. 720 A.
9. Electrons are emitted from a conductor when the conductor is
A. exposed to weak light.
B. cooled rapidly.
C. bombarded by high-speed electrons.
D. subjected to a small voltage.
10. A circuit contains two devices that are connected in parallel. If the resistance of one of these devices is 12 ohms and the resistance of the other device is 4 ohms, the total resistance of the two devices is
A. 0.0625 ohms.
B. 0.333 ohms.
C. 3 ohms.
D. 16 ohms.
11. When a PNP transistor is connected in a circuit in the manner shown in Figure 52 of Electricity and Electronics, it can be used as a power amplifier because
A. the output current will be much smaller than the input current.
B. the output current will be much larger than the input current.
C. the output voltage will be much smaller than the input voltage.
D. the output voltage will be much larger than the input voltage.
12. The function of a capacitor in an electric circuit is to
A. allow current flow between its plates.
B. measure the amount of current in the circuit.
C. increase circuit power.
D. store electric charges.
13. In a cathode ray tube, the number of electrons that reach the fluorescent screen is controlled by the
A. anode.
B. cathode.
C. deflecting plate.
D. grid.
14. Which of the following frequencies falls in the range of RF waves used by commercial radio broadcasting stations?
A. 60 Hz
B. 6,000 Hz
C. 600,000 Hz
D. 6,000,000 Hz
15. To use your left hand to determine the direction of the voltage developed in a moving conductor in a stationary magnetic field, you must point your
A. thumb in the direction of the magnetic flux.
B. thumb in the direction of the electromagnetic force.
C. forefinger in the direction of the lines of force.
D. forefinger in the direction of the motion.
16. A complete circuit contains two parallel-connected devices and a generator for providing the electromotive force. The resistance of the first device is 12 ohms, the resistance of the second device is 4 ohms, and the voltage developed by the generator is 40 V. What is the magnitude of the current flowing through the first device?
A. 3.33 A
B. 8 A
C. 10 A
D. 13.32 A
17. A transformer has a primary voltage of 115 V and a secondary voltage of 24 V. If the number of turns in the primary is 345, how many turns are in the secondary?
A. 8
B. 72
C. 690
D. 1,653
19. An electric heating element is connected to a 110 V circuit and a current of 3.2 A is flowing through the element. How much energy is used up during a period of 5 hours by the element?
A. 352 Wh
B. 550 Wh
C. 1,760 Wh
D. 2,580 Wh
20. The magnitude of the voltage induced in a conductor moving through a stationary magnetic field depends on the _______ and the _______ of the conductor.
A. length, speed
B. distance, circumference
C. resistance, current
D. color, capacitance
21. If a bar of copper is brought near a magnet, the copper bar will be
A. attracted by the magnet.
B. unaffected by the magnet.
C. repelled by the magnet.
D. made into an induced magnet.
22. When all parts of a circuit are composed of conducting materials, the circuit is said to be
A. parallel.
B. shorted.
C. open.
D. closed.
23. When an electron is displaced in a semiconductor, the hole that's left behind is
A. attracted to the negative terminal of the voltage source.
B. incapable of carrying a charge.
C. attracted to the anode of the voltage source.
D. considered an impurity in the crystal.
24. Including a full-wave rectifier in an AC circuit will yield a(n) _______ current.
A. intermittent direct
B. intermittent alternating
C. continuous direct
D. continuous alternating
25. Suppose that you're facing a straight current-carrying conductor, and the current is flowing toward you. The lines of magnetic force at any point in the magnetic field will act in
A. the same direction as the current.
B. a clockwise direction.
C. the direction opposite to the current.
D. a counterclockwise direction.
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This is dealing with sound--
1. Which one of the following frequencies of a wave in the air can be heard as an audible sound by the human ear?
A. 0.10 Hz
B. 10 Hz
C. 1,000 Hz
D. 100,000 Hz
2. If two waves with equal amplitudes and wavelengths travel through a medium in such a way that a particular particle of the medium is at the crest of one wave and at the trough of the other wave at the same time, what will happen to that particle?
A. The particle will vibrate with double amplitude due to resonance.
B. The particle will remain stationary due to interference.
C. The particle will move halfway to the crest due to reinforcement.
D. The particle will cause beats as a result of the wave combination.
3. Which of the following phenomena is taking place when sound waves are reflected from a surface along parallel lines?
A. Diffusion
B. Absorption
C. Refracting
D. Focusing
4. An overtone that's a whole number multiple of the fundamental frequency of a string is called a
A. harmonic.
B. pitch.
C. discordant sound.
D. scale.
5. Sound waves can't travel through
A. a solid.
B. a liquid.
C. an elastic material.
D. a vacuum.
6. The function of the eardrum in the middle ear is to
A. carry the sound energy to the brain.
B. collect the sound waves.
C. amplify the received sound.
D. vibrate with the frequency of the received sound.
7. A wave with a period of 0.008 second has a frequency of
A. 12.5 Hz.
B. 80 Hz.
C. 125 Hz.
D. 800 Hz.
8. During the process of steel production, the flaws in steel casting are detected by
A. infrasonic vibrations.
B. ultrasonic vibrations.
C. longitudinal vibrations.
D. resonant vibrations.
9. When the temperature of the air is 25°C, the velocity of a sound wave traveling through the air is approximately
A. 320 m/s.
B. 332 m/s.
C. 347 m/s.
D. 357 m/s.
10. In a transverse wave that travels through a medium, the molecules of the medium vibrate
A. in the direction in which the wave travels.
B. at right angles to the direction in which the wave travels.
C. at twice the velocity of the molecules in a longitudinal wave.
D. with smaller amplitudes than the molecules in a longitudinal wave.
11. A wave front has the form of a
A. sine wave.
B. surface of a sphere.
C. straight line.
D. circle.
12. If a source of sound waves is rapidly approaching a person, the sound heard by the person appears to have
A. a frequency higher than the original frequency.
B. a period higher than the original period.
C. an amplitude lower than the original amplitude.
D. a pitch lower than the original pitch.
13. In a stringed musical instrument, the part that vibrates in resonance with the sound waves produced by the strings is called the
A. sounding board.
B. diatonic scale.
C. membrane.
D. reed.
14. If a wave hits a smooth surface at an angle of incidence of 40 degrees, the angle of reflection is
A. 0 degrees.
B. 40 degrees.
C. 80 degrees.
D. 90 degrees.
15. When a tuning fork vibrates over an open pipe and the air in the pipe starts to vibrate, the vibrations in the tube are caused by
A. harmonics.
B. reinforcement.
C. beats.
D. resonance.
16. When a sound from a source is refracted away from the surface of the earth, it gives an indication that the
A. air is cooler than the ground.
B. wind is blowing in the direction of the sound.
C. air has high humidity.
D. ground is cooling faster than the air.
17. A sound that's produced by a single wave at a constant frequency and with no overtones is called
A. a mellow sound.
B. a discordant sound.
C. a pure sound.
D. an average sound.
18. In which one of the following locations can a person hear the echo of a sound?
A. Less than 16.6 meters in front of the reflecting surface
B. At least 33.2 meters behind the reflecting surface
C. At least 16.6 meters in front of the reflecting surface
D. Less than 33.2 meters behind the reflecting surface
19. Rarefaction occurs only in a _______ wave.
A. longitudinal.
B. transverse.
C. sympathetic.
D. forced.
20. If a string vibrates at the fundamental frequency of 528 Hz and also produces an overtone with a frequency of 1,056 Hz, this overtone is the
A. first harmonic.
B. second harmonic.
C. third harmonic.
D. fourth harmonic.
21. A surface receiving sound is moved from its original position to a position three times farther away from the source of the sound. The intensity of the received sound thus becomes
A. three times as low.
B. nine times as low.
C. three times as high.
D. nine times as high.
22. The wavelength of a wave is the distance between
A. the amplitude and the normal position.
B. the crest and the following trough.
C. the rarefaction and the following compression.
D. two consecutive crests.
23. If a person is in front of a smooth surface from which a sound is reflected, the person would hear a sound that
A. has a higher intensity than the sound produced by the source.
B. seems to come from behind the surface.
C. has a higher pitch than the sound produced by the source.
D. seems to lack overtones.
24. In a stringed musical instrument, the sound frequency of a particular string can be increased by
A. lengthening the string.
B. loosening the string.
C. tightening the string.
D. increasing the string's thickness.
25. Through which one of the following mediums is the velocity of a sound wave the greatest?
A. Steel
B. Lead
C. Water
D. Air
------------------------------------------------------------------------------------------------ This is dealing with Machanics
1. In which of the following units is acceleration expressed?
A. Newtons
B. Foot-pounds
C. Kilograms
D. Meters per second squared
2. A stone falls from a ledge and takes 8 seconds to hit the ground. The stone has an original velocity of 0 m/s. How tall is the ledge?
A. 1,254.4 meters
B. 313.6 meters
C. 78.4 meters
D. 39.2 meters
3. A tank with a flat bottom is filled with water to a height of 4 meters. What is the pressure at any point at the bottom of the tank? (You can ignore atmospheric pressure when calculating your answer.)
A. 4.0 kPa
B. 9.8 kPa
C. 18.9 kPa
D. 39.2 kPa
4. The ability of a material to transfer heat or electric current is called
A. insulation.
B. porosity.
C. conductivity.
D. convection.
5. A steel block has a volume of 0.08 m³ and a density of 7,840 kg/m³. What is the force of gravity acting on the block (the weight) in water?
A. 5,362.56 N
B. 6,150.64 N
C. 6,700.56 N
D. 7,600.18 N
6. When an automotive battery is fully charged, the sulfuric acid and water mixture will have a specific gravity of about
A. 0.15.
B. 1.0.
C. 1.3.
D. 2.5.
7. If an object has a mass of 20 kg, what is the force of gravity acting on it on earth?
A. 196 N
B. 2.04 kg
C. 32.67 N
D. 1.96 kg
8. If a small-diameter open glass tube is partially immersed in a vessel containing mercury, the surface of the mercury inside the tube will be
A. lower than the mercury in the vessel, and shaped like the outside of an umbrella.
B. higher than the mercury in the vessel, and shaped like the outside of an umbrella.
C. lower than the mercury in the vessel, and shaped like the inside of a bowl.
D. higher than the mercury in the vessel, and shaped like the inside of a bowl.
9. How much time should be allowed for a 605-mile car trip if the car will be traveling at an average speed of 55 miles per hour?
A. 8.75 hours
B. 9 hours
C. 10.5 hours
D. 11 hours
10. A machine is supplied energy at a rate of 4,000 W and does useful work at a rate of 3,760 W. What is the efficiency of the machine?
A. 92 percent
B. 94 percent
C. 96 percent
D. 97 percent
11. What is the kinetic energy of an object that has a mass of 30 kilograms and moves with a velocity of 20 m/s?
A. 2,940 J
B. 5,880 J
C. 6,000 J
D. 12,000 J
12. If a gas has a gage pressure of 156 kPa, its absolute pressure is approximately
A. 56 kPa.
B. 100 kPa
C. 256 kPa.
D. 300 kPa.
13. According to Ptolemy's model of the movement of celestial bodies,
A. the earth rotates around the sun.
B. the sun is the center of the universe.
C. the earth rotates around the moon.
D. planets orbit in circular paths around the earth.
14. A car with a mass of 1,200 kilograms is moving around a circular curve at a uniform velocity of 20 meters per second. The centripetal force on the car is 6,000 newtons. What is the radius of the curve?
A. 160 meters
B. 80 meters
C. 32 meters
D. 16 meters
15. What force is required to accelerate a body with a mass of 15 kilograms at a rate of 8 m/s²?
A. 1.875 kg
B. 23 kg
C. 23 N
D. 120 N
16. Oil flows upward in the wick of a lantern because of the liquid property called
A. viscosity.
B. capillarity.
C. meniscusity.
D. density.
17. A car travels from Boston to Hartford in 4 hours. The two cities are 240 kilometers apart. What was the average speed of the car during the trip?
A. 4 km/hour
B. 36 km/hour
C. 60 km/hour
D. 960 km/hour
18. Which of the following is the term used to describe a body's resistance to a change in motion?
A. Inertia
B. Acceleration
C. Gravity
D. Mass
19. If the velocity of an object changes from 65 m/s to 98 m/s during a time interval of 12 s, what is the acceleration of the object?
A. 2.75 m/s
B. 5.42 m/s
C. 13.58 m/s
D. 33 m/s
20. An object has a mass of 120 kg on the moon. What is the force of gravity acting on the object on the moon?
A. 12.24 N
B. 20 N
C. 196 N
D. 1,176 N
21. In a practical machine, the power output is _______ the power input.
A. smaller than
B. larger than
C. equal to
D. multiplied by
22. If a stone with an original velocity of 0 is falling from a ledge and takes 8 seconds to hit the ground, what is the final velocity of the stone?
A. 39.2 m/s
B. 42.6 m/s
C. 78.4 m/s
D. 156.8 m/s
23. The ratio of output power to input power, in percent, is called
A. conductivity.
B. efficiency.
C. work.
D. horsepower.
24. An object with a mass of 78 kilograms is lifted through a height of 6 meters. How much work is done?
A. 47.75 J
B. 468 J
C. 764.4 J
D. 4,586.4 J
25. A car with a mass of 2,000 kilograms is moving around a circular curve at a uniform velocity of 25 meters per second. The curve has a radius of 80 meters. What is the centripetal force on the car?
A. 625 N
B. 703 N
C. 15,625 N
D. 20,250 N
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Heat
1. A silver bar 0.125 meter long is subjected to a temperature change from 200°C to 100°C. What will be the length of the bar after the temperature change?
A. 0.124764 meter
B. 0.00023635 meter
C. 0.00002363 meter
D. 0.0000189 meter
2. When the molecules in a body move with increased speed, it's possible that the body will change from a
A. gas to a liquid.
B. gas to a solid.
C. liquid to a solid.
D. liquid to a gas.
3. If the absolute temperature of a gas is 600 K, the temperature in degrees Celsius is
A. 273°C.
B. 327°C.
C. 705°C.
D. 873°C.
4. The main purpose of the turbine in the turbojet engine is to
A. drive the compressor.
B. compress the air.
C. increase the velocity of the exhaust gases.
D. reduce the temperature of the exhaust gas.
5. 20 cubic inches of a gas with an absolute pressure of 5 psi is compressed until its pressure reaches 10 psi. What is the new volume of the gas? (Assume that there's no change in temperature.)
A. 5 cubic inches
B. 10 cubic inches
C. 40 cubic inches
D. 100 cubic inches
6. Unlike other kinds of liquids, volatile liquids
A. ignite readily at a relatively low temperature.
B. flow rapidly at a relatively low temperature.
C. evaporate rapidly at a relatively low temperature.
D. freeze readily at a relatively high temperature.
7. A temperature of 273 K is the temperature at which water
A. boils.
B. lacks any moving molecules.
C. evaporates.
D. freezes.
8. Which of the following takes place in the combustion chamber of a gas turbine engine?
A. Fuel oil is stored with sufficient pressure.
B. Fuel oil is mixed with a proper portion of compressed air.
C. A mixture of fuel oil and compressed air is ignited.
D. Gases are cooled to a desired temperature.
9. How much heat energy is required to raise the temperature of 5 kilograms of coal from 20°C to 220°C?
A. 314 J
B. 6,573 J
C. 1,314,718 J
D. 4,187,000 J
10. One degree Celsius indicates the same temperature change as
A. one degree Fahrenheit.
B. one kelvin.
C. 5/9 degree Fahrenheit.
D. 9/5 kelvin.
11. A quantity of a gas has an absolute pressure of 400 kPa and an absolute temperature of 110 degrees kelvin. When the temperature of the gas is raised to 235 degrees kelvin, what is the new pressure of the gas? (Assume that there's no change in volume.)
A. 1.702 kPa
B. 3.636 kPa
C. 510 kPa
D. 854.46 kPa
12. A temperature of 20°C is equivalent to approximately
A. -6°F.
B. 32°F.
C. 68°F.
D. 136°F.
13. If the absolute pressure of a gas is 550.280 kPa, its gage pressure is
A. 101.325 kPa.
B. 277.280 kPa.
C. 448.955 kPa.
D. 651.605 kPa.
14. Which one of the following substances is a liquid fuel used in rocket engines?
A. Liquid oxygen
B. Ammonia
C. Potassium perchlorate
D. Codium nitrate
15. The density of water is the greatest at a temperature of
A. 0 K.
B. 4 K.
C. 273 K.
D. 277 K.
16. In a gasoline engine, the area in the cylinder head where the air-and-fuel mixture is burned is called the
A. piston.
B. cylinder.
C. combustion chamber.
D. intake valve.
17. How much heat is required to convert 0.3 kilogram of ice at 0°C to water at the same temperature?
A. 100,375 J
B. 167,292 J
C. 334,584 J
D. 450,759 J
18. Which of the following cools the air in a household refrigerator?
A. Reduction of the air temperature due to condensation of the gaseous refrigerant
B. The transfer of heat from the air to the compressor due to expansion of the gaseous refrigerant
C. The transfer of heat to the evaporator due to compression of the liquid refrigerant
D. Absorption of the heat from the air due to evaporation of the liquid refrigerant
19. Which one of the following temperatures is equal to 5°C?
A. 0 K
B. 41 K
C. 278 K
D. 465 K
20. Liquid alcohol will change to vapor when its temperature reaches the
A. boiling point.
B. fusing point.
C. freezing point.
D. melting point.
21. A temperature of 200°F is equivalent to approximately
A. 37.8°C.
B. 93.3°C.
C. 232°C.
D. 840°C.
22. A quantity of gas has a volume of 0.20 cubic meter and an absolute temperature of 333 degrees kelvin. When the temperature of the gas is raised to 533 degrees kelvin, what is the new volume of the gas? (Assume that there's no change in pressure.)
A. 0.0006 m3
B. 0.2146 m3
C. 0.2333 m3
D. 0.3198 m3
23. Which of the following statements correctly describes the position of the intake and exhaust valves during most of the power stage in a four-cycle gas engine?
A. The intake valve is closed and the exhaust valve is open.
B. The intake valve is open and the exhaust valve is closed.
C. Both the intake valve and the exhaust valve are closed.
D. Both the intake valve and the exhaust valve are open.
24. What is the length of an aluminum rod at 65°C if its length at 15°C is 1.2 meters?
A. 0.001386 meter
B. 0.00180 meter
C. 1.201386 meters
D. 1.214855 meters
25. Heat from burning fuel warms the walls of the firebox section of the furnace in
A. a hot-air heating system.
B. an evaporation system.
C. a compressor compartment.
D. a hot-water heating system.
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| Question Expires: |
Question closed |
| End Time: |
2006-06-06 14:16:38 Started:
2006-06-06 13:20:22
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