Q&A Hero

Q: A car increases its speed from 60 to 65 miles per hour in the same time that a bicycle increases its speed from rest to 5 miles per hour. Acceleration is 1) greater for the car, 2) greater for the bicycle, 3) the same for each, principally because 4) the car undergoes the greater change in velocity. 5) the bicycle has considerably less mass. 6) both undergo equal increases in velocity during the same interval of time.

Q: An object is accelerating if it moves 1) with constant velocity 2) in a circular path 3) in a straight-line path because it is undergoing a change in its 4) speed. 5) direction. 6) net force.

Q: To say that an object is moving at constant velocity means that it is 1) at rest, 2) moving at an unchanging speed, 3) moving at an unchanging speed in a straight-line path, and that its acceleration is 4) zero. 5) constantly increasing (or decreasing). 6) uniform.

Q: To say that an object is being accelerated, means that 1) it is at rest, 2) it is moving, 3) it is either at a state of rest or a state of constant velocity, 4) its state of motion is changing, and we define acceleration to be 5) a change in speed. 6) a change in velocity. 7) the rate at which speed changes. 8) the rate at which velocity changes.

Q: Figure V-8 Which of the sailboats shown sails fastest in its forward direction? 1) 1 2) 2 3) 3 4) None sails forward. It is interesting to note that the force of the wind impact is 5) nonexistent on each sail. 6) greatest on 1. 7) greatest on 2. 8) greatest on 3.

Q: Figure V-7 The boat to make the fastest progress in its forward direction is boat 1) 1. 2) 2. 3) 3. 4) 4. Boat 3 is not propelled in a forward direction because 5) the wind does not make impact with the sail. 6) there is no component of force parallel to the keel. 7) of air resistance on the front of the sail. 8) But it is propelled in a forward direction!

Q: Figure V-6 The boat that will sail fastest in the intended direction is 1) 1, 2) 2, 3) 3, 4) 4, and the boat that responds least to the wind is 5) 1. 6) 2. 7) 3. 8) 4.

Q: Figure V-4 Which of the sailboats shown sails the fastest in its forward direction? 1) 1 2) 2 3) 3 4) 4 It is interesting to note that 5) this is the only boat that sails forward. 6) only two of the boats sail forward. 7) three out of the four boats sail forward. 8) all sail forward, but at different speeds.

Q: Figure V-5 A small railroad car is pulled by a rope as shown in the sketch (top view). The force F that the rope exerts on the car has a component along the track and another component perpendicular to the track. Judging from the diagram, the larger of these two components would be 1) along the track. 2) perpendicular to the track. These components will be equal if 3) the rope makes an angle of 45o with the track. 4) the rope is pulled in a direction along the track, rather than at an angle to it. 5) they form an action-reaction pair on the car. 6) but they can never really be equal.

Q: The airspeed of an airplane is 100 km/h. When it is caught in a 100-km/h right-angled crosswind, its speed across the ground below is about 1) 0 km/h. 2) 100 km/h. 3) 140 km/h. 4) 200 km/h. 5) more than 200 km/h. If the airplane changes direction and flies at 60 degrees to the wind, its ground speed will 6) decrease. 7) remain the same. 8) increase.

Q: Figure V-3 The weight of the barrel on the slope is shown by the vector which has components (not shown) parallel to the surface of the incline and perpendicular to the surface of the incline. Judging from the slope of incline, the greater of these two components is 1) parallel to the slope. 2) perpendicular to the slope. 3) both the same. 4) need more information If the slope of the incline were steeper, this component vector would 5) decrease. 6) remain the same. 7) increase. 8) again, can't really say.

Q: Figure V-2 A block is pulled across a floor as shown in the vector diagram. The greater component of F is in the 1) horizontal direction, 2) vertical direction, although both horizontal and vertical components would be of equal magnitude if vector F were 3) horizontal. 4) vertical. 5) at an angle of 45o.

Q: Figure V-1 A block is pulled across a floor as shown in the vector diagram. The force vector F has the greater component in the 1) horizontal direction, 2) vertical direction, and this component is 3) larger than the vector F. 4) smaller than the vector F. 5) equal to the vector F.

Q: A spear 10 meters long is thrown at a relativistic speed through a pipe that is 10 meters long (both these dimensions are measured when each is at rest). When the spear passes through the pipe, which of the following statements best describes what is observed? 1) The spear shrinks so that the pipe completely covers it at some point. 2) The pipe shrinks so that the spear extends from both ends at some point. 3) Both shrink equally so the pipe just barely covers the spear at some point. 4) any of these, depending on the motion of the observer (moving with the spear, at rest with the pipe, etc.) An observer fixed to the pipe would measure the mass of the spear to be greater than when at rest; an observer moving with the spear would measure the mass of the pipe to be 5) more than when at rest. 6) less than when at rest. 7) the same as when at rest.

Q: If the Sun collapsed to a neutron star or black hole, Earth would 1) spiral into the Sun's core, 2) remain in its present orbit, 3) spiral away from the Sun, 4) itself undergo collapse, for the variable that changes in Newton's gravitational equation is 5) distance. 6) the mass of the Sun. 7) the mass of Earth. 8) all of these. 9) none of these.

Q: Strictly speaking, from the point of view of a person on the ground floor of a tall skyscraper, a person at the top ages 1) more slowly, 2) faster, 3) the same, and from the point of view of a person at the top of the skyscraper, the person at the ground level ages 4) more slowly. 5) faster. 6) the same.

Q: An astronaut falling into a black hole would see events toward the singularity 1) red shifted, 2) blue shifted, 3) with no shift, and she would see events from the outside normal universe 4) red shifted. 5) blue shifted. 6) with no shift.

Q: When light is gravitationally red or blue shifted, that which is shifted is 1) wave frequency, 2) wavelength, 3) wave energy, 4) all of these, 5) none of these, and when light is Doppler shifted, that which is shifted is actually 6) wave frequency. 7) wave amplitude. 8) both of these. 9) none of these.

Q: cannot distinguish between observations made in an accelerating frame and a gravitational field.

Q: Light bends as it 1) passes a massive star, 2) traverses any gravitational field, 3) both of these, 4) none of these, and when emitted from a massive star, light is 5) red shifted. 6) blue shifted. 7) speeded up. 8) none of these.

Q: Special relativity is most concerned with 1) uniform motion, 2) accelerated motion, 3) the warping of space-time, 4) gravitation, whereas general relativity is more concerned with 5) uniform motion. 6) accelerated motion. 7) energy and mass. 8) time.

Q: If you were traveling at the speed of light, next to a beam of light, the beam would appear to 1) be at relative rest, traveling beside you at an equal speed. 2) still travel away from you, but at a speed less than c. 3) travel away from you at c. From this we see that the speed of light in free space will be found to 4) have the same value for all observers. 5) be relative to the motion of the observer.

Q: As a particle is accelerated to relativistic speeds, laboratory measurements of its momentum show 1) an increase, 2) a decrease, 3) no change, and measurements of its volume show 4) an increase. 5) a decrease. 6) no change.

Q: According to special relativity 1) space and time are aspects of each other. 2) mass and energy are aspects of each other, 3) both of the above, 4) neither of the above, and the underlying postulate of special relativity is 5)F = ma. 6) E = mc2. 7) that the speed of light has a constant value for all observers.

Q: Figure A-5If the mass per nucleon in atomic nuclei varied as shown in the fictitious plot above, then nuclear energy would be available from the element iron (atomic no.26) by the process of nuclear1) fission.2) fusion.3) both.4) neither.Accordingly, krypton (atomic no.36) would yield energy by nuclear5) fission.6) fusion.7) both.8) neither.9) not enough information to say.

Q: Figure A-4If the mass per nucleon in atomic nuclei varied as shown in the fictitious plot above, then nuclear energy would be available from the element iron (atomic by no. 26 the process of nuclear1) fission.2) fusion.3) both.4) neither.Accordingly, krypton (atomic no. 36) would yield energy by nuclear5) fission.6) fusion.7) both.8) neither.9) not enough information to say.

Q: Figure A-3If the mass per nucleon in atomic nuclei varied as shown in the fictitious plot above, then nuclear energy would be available from the element iron (atomic no. 26 by the process of nuclear1) fission.2) fusion.3) both.4) neither.Accordingly, hydrogen would yield energy by nuclear5) fission.6) fusion.7) both.8) neither.9) not enough information to say.

Q: Figure A-2If the mass per nucleon in atomic nuclei varied as shown in the fictitious plot above, then nuclear energy would be available from the element iron (atomic no. 26 by the process of nuclear1) fission.2) fusion.3) both.4) neither.Accordingly, uranium would yield energy by nuclear5) fission.6) fusion.7) both.8) neither.

Q: When heavy elements such as uranium undergo fission, there is an accompanying 1) loss of mass, 2) gain of mass, 3) no change in mass, and when light elements such as hydrogen undergo fusion, there is an accompanying 4) loss of mass. 5) gain of mass. 6) no change in mass.

Q: The energy released by the Sun is the outcome of atomic nuclei 1) breaking apart, 2) combining together, and radioactive by-products are a chief result of atomic nuclei 3) breaking apart. 4) combining together. 5) doing neither.

Q: Radioactive by-products mostly occur when atomic nuclei 1) break apart, 2) combine together, and radioactive by-products are a chief result of atomic nuclei 3) breaking apart. 4) combining together. 5) doing neither.

Q: A radioactive isotope has a half-life of one week. At the end of two weeks the amount remaining is 1) none, 2) one-eighth, 3) one-quarter, 4) one-half, and at the end of three weeks the amount remaining is 5) none. 6) one-eighth. 7) one-quarter. 8) one-half.

Q: Radioactive isotope A has a half-life of one year, while radioactive isotope B has a half-life of one day. If equal numbers of atoms of each are present, which will give the highest reading on a Geiger counter? 1) A 2) B 3) both the same How much of the original sample of radioactive isotope A will be left at the end of the second year? 4) none 5) one-quarter 6) one-half 7) one-eighth

Q: A radioactive isotope has a half-life of one month. At the end of one month, the amount of the original isotope still remaining is 1) none, 2) one-quarter, 3) one-half, 4) three-fourths, and at the end of two months, the amount of original isotope remaining is 5) none. 6) one-fourth. 7) one-half. 8) three-fourths.

Q: A new theory conforms to the Correspondence Principle when it 1) successfully accounts for the verified results of the old theory. 2) corresponds to all theories of nature. 3) states the essence of the old theory, but in an up-to-date way. 4) successfully ties two or more theories together. The Correspondence Principle is applicable 5) principally at the atomic level. 6) in all realms of physics. 7) for all good theory, scientific or otherwise.

Q: Orbital electrons do not spiral into the atomic nucleus because of 1) electrical forces, 2) the wave nature of the electrons, 3) angular momentum, 4) the discreteness of energy levels, 5) quantum mechanical laws, and the electrons have discrete radii from the nucleus because 6) the circumference of each orbit is an integral multiple of the electron wavelength. 7) electrical forces act over discrete distances. 8) energy levels themselves are discrete.

Q: The ratio of the circumference of any circle to its diameter is π. Similarly, the ratio of the energy of any photon to its frequency is 1) h, Planck's constant, 2) uncertain, unlike π, 3) the wavelength of the photon, 4) c, the photon's speed, which is 5) a basic constant of nature setting a lower limit on the smallness of things. 6) a basic constant of nature setting an upper limit on the speed of things.

Q: The diameter of a mercury atom, atomic number 80, compared with the diameter of a zirconium atom, atomic number 40, is approximately 1) half as large 2) twice as large 3) the same size because the 4) atomic masses are not appreciably different. 5) greater nuclear charge pulls the orbiting electrons closer. 6) atomic number and atomic diameter are directly proportional to each other. 7) atomic number and atomic diameter are inversely proportional to each other.

Q: The Uncertainty Principle states that 1) all measurements are essentially incorrect to some degree. 2) no measurement is exact. 3) we cannot in principle know both the position and momentum (or energy and time) of a particle with absolute certainty. 4) science itself is essentially uncertain. The Uncertainty Principle is applicable 5) only in the atomic domain. 6) in all physical domains, from the nuclear to the cosmic. 7) in all areas of good theory, scientific or otherwise.

Q: Refer to the figure above. Suppose that an electron makes a transition from n = 3 to n = 2 and emits a photon of frequency 4 1014 Hz. Then an electron that makes a transition from n = 3 to n = 1 may emit a photon with a frequency of 1) 1 1014 Hz, 2) 3 1014 Hz, 3) 4 1014 Hz, 4) 9 1014 Hz, which is consistent with emission of the most energetic photon from a transition from n = 3 to 5) n = 1. 6) n = 2. 7) either, as both transitions are equivalent.

Q: Figure A-1 Refer to the figure above. Assuming that all transitions between levels are possible, how many spectral lines will this atom exhibit? 1) 1 2) 2 3) 3 4) 4 5) 5 The spectral line of highest frequency will result from an electron transition from n = 3 to 6) n = 2. 7) n = 1. 8) either, if the levels are equidistant.

Q: The thing that is different between x-rays and radio waves is1) their charges,2) their masses,3) their frequencies,4) the medium through which they travel,5) the speeds at which they travel,and the thing that is the same for x-rays and radio waves is6) their masses.7) their frequencies.8) the medium through which they travel.9) the speeds at which they travel.10)none of these.

Q: Light from a laser is 1) monochromatic. 2) in phase. 3) coherent. 4) all of the above. Compared to the energy put into a laser, the energy of the laser beam is 5) usually much more. 6) much less. 7) the same.

Q: Figure L-3 The radiation curve is a plot of light intensity versus frequency for an incandescent source such as a glowing lamp filament. If the source of light were excited atoms in the gaseous phase, the radiation curve would look like 1) I. 2) II. 3) III. 4) IV. The plot shown in IV is of 5) monochromatic light. 6) a very bright source. 7) light that has passed through a thin slit.

Q: Figure L-2 The radiation curve is a plot of light intensity versus frequency for an incandescent source. If this light is first passed through a cool gas, the resulting radiation curve would most probable look like 1) I. 2) II. 3) III. This best illustrates that the atoms of gas have 4) been excited. 5) absorbed part of the light. 6) simplified selective frequencies of the transmitted light.

Q: Figure L-1 The diagram is of a simple spectroscope. If lens #1 were omitted, the resulting spectrum would be 1) much dimmer. 2) upside down. 3) no different. If, instead, the slit were opened too wide, the middle of the spectrum would appear 4) white. 5) much narrower. 6) black. 7) a broader yellow.

Q: A spectrum of colors seen in gasoline on a wet street is primarily a result of 1) interference, 2) polarization, 3) refraction, 4) scattering, 5) diffraction, where 6) the light reaching the eye is polarized by double reflection. 7) only the higher frequencies of light resonate with the gasoline and H2O molecules. 8) the thin film of gasoline spreads the light out into its component colors. 9) light reflecting from the gasoline surface interferes with light reflecting from the water surface.

Q: If the sky were ordinarily yellow-orange instead of blue, then sunsets would appear 1) orange, 2) green, 3) blue, 4) black, which has to do with 5) the polarization of sunlight. 6) yellow-orange and sky blue being complementary colors. 7) the refraction of sunlight through the thicker atmosphere.

Q: The "after glow" from some clock faces is caused by atoms 1) being excited, 2) vibrating at frequencies greater than a million billion times per second, 3) remaining for some time in a state of excitation before de-exciting, and materials exhibiting this property are called 4) fluorescent. 5) phosphorescent. 6) incandescent. 7) luminescent.

Q: A pinhole cameras has no lens. The tiny pin-hole opening insures that rays of light from different parts of an object 1) overlap. 2) don't overlap. 3) bend to a focus. Small openings between leaves in a tree act as pinholes. The round spots of light cast on the ground below are images of 4) the Sun. 5) the openings themselves. 6) both of these 7) neither of these

Q: Rainbows exist because light in water drops is 1) reflected. 2) refracted. 3) both of these And the main reason drops disperse different colors involves light's different 4) frequencies. 5) speeds. 6) directions. 7) energies.

Q: Light passes readily through a pair of Polaroids when their axes are 1) parallel. 2) perpendicular. 3) neither of these, and for a pair of Polaroids with axes at 45 degrees to each other 4) light will not pass. 5) light that passes is dimmer than for parallel Polaroids. 6) another Polaroid is necessary for any light to pass.

Q: A 2-m-tall person viewing his full-length image in a plane mirror requires a mirror that is at least 1) any visible size. 2) 2 m tall. 3) 1 m tall. The size of mirror required 4) depends on how far away from it he stands. 5) does not depend on how far away from it he stands.

Q: A ray of light is incident on a pane of common window glass at an angle of 35o to the normal. The angle of the reflected ray with respect to the normal is 1) 35o 2) 55o 3) 90o 4) 20o and the refracted ray within the glass may be at an angle of 5) 35o. 6) 55o. 7) 22o. 8) 75o.

Q: Strictly speaking, if a beam of white light is shone through a piece of very thick glass, the first color to emerge from the other side is 1) white. 2) violet. 3) red. 4) green. This is because 5) all frequencies travel at c. 6) lower frequencies undergo more refraction in a medium. 7) higher frequencies of light travel at a faster average speed through a medium. 8) higher frequencies of light interact with more molecules in a medium.

Q: A device that transforms electrical energy to mechanical energy is 1) a generator, 2) a motor, 3) a transformer, 4) any common magnet, and a device that transforms mechanical energy into electrical energy is a 5) generator. 6) motor. 7) transformer.

Q: Figure E/M-4 Refer to the figure above. Assume the switch in the primary has been closed for a few minutes. Then there is a current in the 1) primary, but not the secondary. 2) secondary, but not the primary. 3) primary and secondary. 4) neither the primary nor the secondary. When the switch is opened suddenly, current in the primary 5) decreases, while current builds up in the secondary. 6) increases, while current decreases in the secondary.

Q: Figure E/M-3 Refer to the figure above. When the switch is closed in the primary circuit, 1) voltage is established in the primary coil 2) a current is established in the primary coil 3) a magnetic field builds up around the primary coil 4) all of the above and a voltage is induced in the secondary circuit principally because 5) of the voltage in the primary. 6) of the change of current in the primary. 7) the expanding magnetic field about the primary is sensed by the secondary.

Q: In a 120-volt circuit, 120 joules of 1) charge move each second, which makes up the current, 2) energy are given to each unit of charge that makes up the current, 3) energy are given to each unit of resistance in the circuit, and if the current is 1 ampere, then 4) 1 unit of charge per second passes any point in the circuit. 5) 120 units of charge per second pass any point in the circuit. 6) the resistance of the circuit is 1 ohm.

Q: The electrons that make up the current in an electric circuit move by 1) interacting with the electric field established in the circuit. 2) bumping into one another in such as way as to send pulses over long distances. The drift speed of individual electrons making up the current is 3) very low, about a snail's pace. 4) about the speed of sound. 5) about the speed of light.

Q: For three identical lamps in parallel with a 1.5-volt dry cell, the voltage across the lower lamp is 1) 1/2 V. 2) 1 V. 3) 1.5 V. 4) 3 V. If that lamp is disconnected, the other two lamps will 5) glow the same. 6) glow much more brightly. 7) glow much more dimly.

Q: Figure E/M-2Refer to the identical lamps above. If the current in lamp 1 is one ampere, then the current in lamp 2 is1) 1/2 A2) 1/3 A3) 1 A4) 2 A5) 3 Aand the voltage across lamp 2 is6) 1/2 V.7) 1/3 V.8) 1 V.9) 1.5 V.10)3 V.

Q: In a series circuit of three identical lamps powered by a 1.5-volt dry cell, the voltage across each lamp is 1) 1/2 V. 2) 1 V. 3) 1-1/2 V. If any one of the lamps is disconnected, the other lamps will 4) go out. 5) continue to glow.

Q: Figure E/M-1Refer to the identical lamps above. If the current in lamp 1 is one ampere, then the current in lamp 2 is1) 1/2 ampere,2) 1/3 ampere,3) 1 ampere,4) 2 amperes,and the total current in the lamps and in the dry cell is5) 0.6) 1/2 ampere.8) 1/3 ampere.9) 1 ampere.10)3 amperes.

Q: When two lamps are connected in series to a battery, the electrical resistance that the battery senses is 1) more than the resistance of either lamp, 2) less than the resistance of either lamp, And when the same two lamps are connected in parallel to a battery, the electrical resistance that the battery senses is 3) more than the resistance of either lamp. 4) less than the resistance of either lamp. 5) none of these

Q: The source of electrons lighting common lamps in your classroom is 1) the power company, 2) the electrical outlet, 3) atoms in the lamp filament, 4) the wires leading to the lamp, whereas the source of energy that lights a common lamp in your home is 5) the power company. 6) the electrical outlet. 7) atoms in the bulb filament. 8) the wires leading to the lamp.

Q: Ohm's law tells us that the amount of current produced in a circuit is 1) directly proportional to voltage. 2) inversely proportional to resistance. 3) both of these which means that current in a conductor can be increased by 4) increasing the voltage across it. 5) reducing its resistance. 6) both of these D) none of the above

Q: Electric potential energy is measured in 1) amperes. 2) volts. 3) joules. 4) watts and electric potential is measure in 5) amperes. 6) volts. 7) joules. 8) watts

Q: A bird sitting on a bare high-voltage wire is not electrocuted because 1) of the high resistance of its body. 2) of no electrical potential difference across its body. 3) its body is at a low electric potential compared to the wire. 4) the high voltage across its feet produces a very small current. If the bird stood on the wire with only one foot, it would 5) be electrocuted. 6) remain unharmed.

Q: A hydrogen atom consists of a single proton and a single electron. If the distance between the proton and the electron were doubled, the electric force would be 1) 1/4 as much, 2) 1/2 as much, 3) twice as much, 4) not enough information to say, and if instead the distance between the electron and proton were halved, the electric force would be 5) 1/4 as much. 6) 1/2 as much. 7) twice as much. 8) four times as much. 9) not enough information to say

Q: A pair of like electric charges 1) repel each other, 2) attract each other, and a pair of like magnetic poles 3) repel each other. 4) attract each other.

Q: The force that holds atoms together to form molecules is 1) electric, 2) magnetic, 3) gravitational, 4) nuclear, and the force that holds the protons in a nucleus together is 5) electric. 6) magnetic. 7) gravitational. 8) nuclear.

Q: Protons and electrons 1) repel each other. 2) attract each other. 3) do not interact with each other. If the distance between a proton and an electron is doubled, the electrical force is 4) 1/4 as much. 5) 1/2 as much. 6) the same. 7) twice as much. 8) four times as much.

Q: Refraction occurs for both sound and light. When refraction occurs there is a change in 1) frequency. 2) wavelength. 3) speed. 4) all of the above. When sound travels faster near the ground than above, bending of sound tends to be 5) upward. 6) downward. 7) neither of these.

Q: Figure S-4 A supersonic aircraft flies between observers A and B as shown. The resulting sonic boom will soon be heard by 1) only observer A. 2) only observer B. 3) both A and B. 4) neither A nor B. The intensity of the sonic boom depends on the 5) speed of the aircraft. 6) size of the aircraft. 7) distance from the aircraft. 8) all of the above. 9) none of the above.

Q: Figure S-3 A V-shaped bow wave is produced when a boat moves 1) more slowly than the velocity of waves in the water. 2) as fast as the waves in the water. 3) faster than the velocity of waves in the water. 4) at any speed, slower or faster than the water waves. Which bow wave corresponds to the faster-moving boat? 5) I 6) II

Q: The aircraft that generates a shock wave will fly at 1) half the speed of sound. 2) exactly the speed of sound. 3) twice the speed of sound. 4) all of these. A sonic boom is produced by a missile traveling 5) near the speed of sound. 6) at the speed of sound. 7) only above the speed of sound. 8) near, at, or above the speed of sound.

Q: When a source of sound approaches, measurements will show an increase in the sound's 1) speed, 2) frequency, 3) wavelength, 4) all of these, 5) none of these, and when a source of sound recedes, measurements will show an increase in the sound's 6) speed. 7) frequency. 8) wavelength. 9) all of these. 10) none of these.

Q: If the handle of a tuning fork is held solidly against a table, its resulting sound is 1) louder, 2) softer, 3) doesn't change, and as a result of this, the length of time the fork keeps vibrating 4) increases. 5) decreases. 6) doesn't change.

Q: Compared to a soft sound, the speed of a loud sound is 1) less, 2) greater, 3) the same, and compared to low-frequency sound, higher-frequency sound travels 4) more slowly. 5) faster. 6) the same speed.