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Chapter: 14 -Problem: 34 >> A small block is attached to an ideal spring and is moving in SHM on a horizontal, frictionless surface. When the amplitude of the motion is 0.090 m, it takes the block 2.70 s to travel from x = 0.090 to x = – 0.090 m. If the amplitude is doubled, to 0.180 m, how long does it take the block to travel(a) From x = 0.180 m to x = – 0.180 m (b) From x = 0.090 m to x = – 0.090 m?
Answer Preview: Identify The motion is SHM and in each case the motion described is one half of a …

, Chapter: 13 -Problem: 13 >> If a projectile is fired straight up from the earth’s surface, what would happen if the total mechanical energy (kinetic plus potential) is(a) Less than zero, and(b) Greater than zero? In each case, ignore air resistance and the gravitational effects of the sun, the moon, and the other planets.
Answer Preview: a b To just barely escape from the earth the initial total mech…

, Chapter: 26 -Problem: 86 >> Assume that a typical open ion channel spanning an axon’s membrane has a resistance of 1 × 1011 ?. We can model this ion channel, with its pore, as a 12-nm-long cylinder of radius 0.3 nm. What is the resistivity of the fluid in the pore?(a) 10 ? ? m; (b) 6 ? ? m;(c) 2 ? ? m;(d) 1 ? ? m. The portion of a nerve cell that conducts signals is called an axon. Many of the electrical properties of axons
Answer Preview: IDENTIFY and SET UP R L A EXECUTE Solve for which is choi…

, Chapter: 37 -Problem: 36 >> Electrons are accelerated through a potential difference of 750 kV, so that their kinetic energy is 7.50 × 105 eV.(a) What is the ratio of the speed v of an electron having this energy to the speed of light, c?(b) What would the speed be if it were computed from the principles of classical mechanics?
Answer Preview: IDENTIFY With such a large potential difference the electron…

, Chapter: 13 -Problem: 43 >> Two satellites are in circular orbits around a planet that has radius 9.00 × 106 m. One satellite has mass 68.0 kg, orbital radius 5.00 × 107 m, and orbital speed 4800 m s. The second satellite has mass 84.0 kg and orbital radius 3.00 × 107 m. What is the orbital speed of this second satellite?
Answer Preview: Identify We know orbital data speed and orbital radius …

, Chapter: 3 -Problem: 68 >> A firefighting crew uses a water cannon that shoots water at 25.0 m/s at a fixed angle of 53.0° above the horizontal. The firefighters want to direct the water at a blaze that is 10.0 m above ground level. How far from the building should they position their cannon? There are two possibilities; can you get them both?
Answer Preview: IDENTIFY The water follows a parabolic trajectory since it is affected only by gravity so we apply t…

, Chapter: 16 -Problem: 80 >> In some applications of ultrasound, such as its use on cranial tissues, large reflections from the surrounding bones can produce standing waves. This is of concern because the large pressure amplitude in an antinode can damage tissues. For a frequency of 1.0 MHz, what is the distance between antinodes in tissue? (a) 0.38 mm;(b) 0.75 mm;(c) 1.5 mm;(d) 3.0 mm. A typical ultrasound transducer used fo
Answer Preview: IDENTIFY and SET UP In a standing wave pattern the distance between antinod…

, Chapter: 17 -Problem: 20 >> A person pours a cup of hot coffee, intending to drink it five minutes later. To keep the coffee as hot as possible, should she put cream in it now or wait until just before she drinks it? Explain.
Answer Preview: The heat lost by the coffee during the five minutes is propor…

, Chapter: 9 -Problem: 121 >> A sphere with radius R = 0.200 m has density that decreases with distance r from the center of the sphere according to ? = 3.00 × 103 kg/m3 – (9.00 × 103 kg/m4)r.(a) Calculate the total mass of the sphere.(b) Calculate the moment of inertia of the sphere for an axis along a diameter.
Answer Preview: Identify The density depends on the distance from the center of the sphere so it …

, Chapter: 13 -Problem: 10 >> Which takes more fuel: a voyage from the earth to the moon or from the moon to the earth? Explain.
Answer Preview: At a given distance from each the attracti…

, Chapter: 27 -Problem: 12 >> Each of the lettered points at the corners of the cube in Fig. Q27.12 represents a positive charge q moving with a velocity of magnitude v in the direction indicated. The region in the figure is in a uniform magnetic field BÌ…(vector), parallel to the x-axis and directed toward the right. Which charges experience a force due to BÌ…(vector) ? What is the direction of the force on each charge? Figur
Answer Preview: The direction of the force is given by the right hand rule that is illustrated in Fig 27 7 If v …

, Chapter: 33 -Problem: 37 >> Physicians use high-frequency (f = 195 MHz) sound waves, called ultrasound, to image internal organs. The speed of these ultrasound waves is 1480 m/s in muscle and 344 m/s in air. We define the index of refraction of a material for sound waves to be the ratio of the speed of sound in air to the speed of sound in the material. Snell’s law then applies to the refraction of sound waves.(a) At what an
Answer Preview: IDENTIFY Snells law applies to the sound waves in the heart SET UP n a sin a n b sin b If …

, Chapter: 4 -Problem: 55 >> A 4.80-kg bucket of water is accelerated upward by a cord of negligible mass whose breaking strength is 75.0 N. If the bucket starts from rest, what is the minimum time required to raise the bucket a vertical distance of 12.0 m without breaking the cord?
Answer Preview: Identify Apply Newtons second law to the bucket and co…

, Chapter: 4 -Problem: 25 >> A horse is hitched to a wagon. Since the wagon pulls back on the horse just as hard as the horse pulls on the wagon, why doesn’t the wagon remain in equilibrium, no matter how hard the horse pulls?
Answer Preview: The motion of an object depends on th…

, Chapter: 14 -Problem: 96 >> By what percentage does the frequency of oscillation change if ksurf= 5 N/m?(a) 0.1%;(b) 0.2%;(c) 0.5%;(d) 1.0%. One technique for making images of surfaces at the nanometer scale, including membranes and biomolecules, is dynamic atomic force microscopy. In this technique, a small tip is attached to a cantilever, which is a flexible, rectangular slab supported at one end, like a diving board. The
Answer Preview: IDENTIFY and SET UP The frequency is and we want f f EXECUTE Using And calli…

, Chapter: 18 -Problem: 23 >> The discussion in Section 18.4 concluded that all ideal monatomic gases have the same heat capacity CV. Does this mean that it takes the same amount of heat to raise the temperature of 1.0 g of each one by 1.0 K? Explain your reasoning.
Answer Preview: No All ideal diatomic gases have the same molar heat capacity C V Therefore if the …

, Chapter: 9 -Problem: 87 >> A disk of radius 25.0 cm is free to turn about an axle perpendicular to it through its center. It has very thin but strong string wrapped around its rim, and the string is attached to a ball that is pulled tangentially away from the rim of the disk (Fig. P9.65). The pull increases in magnitude and produces an acceleration of the ball that obeys the equation α(t) = At, where t is in seconds and A
Answer Preview: Identify The angular acceleration of the disk is rela…

, Chapter: 12 -Problem: 15 >> An old question is “Which weighs more, a pound of feathers or a pound of lead?” If the weight in pounds is the gravitational force, will a pound of feathers balance a pound of lead on opposite pans of an equal-arm balance? Explain, taking into account buoyant forces.
Answer Preview: A mass of feathers for which the weight is one pound has a much larger vo…

, Chapter: 26 -Problem: 81 >> You set up the circuit shown in Fig. 26.20, where C = 5.00 × 10-6F. At time t = 0, you close the switch and then measure the charge q on the capacitor as a function of the current i in the resistor. Your results are given in the table: (a) Graph q as a function of i. Explain why the data points, when plotted this way, fall close to a straight line. Find the slope and y-intercept of the straight l
Answer Preview: IDENTIFY and SET UP Kirchhoffs rules apply to the circuit Taking a loop around the circuit give…

, Chapter: 34 -Problem: 20 >> If a piece of photographic film is placed at the location of a real image, the film will record the image. Can this be done with a virtual image? How might one record a virtual image?
Answer Preview: The rays of light do not converge at a virtual image but instead seem to com…

, Chapter: 3 -Problem: 54 >> Spiraling Up. It is common to see birds of prey rising upward on thermals. The paths they take may be spiral-like. You can model the spiral motion as uniform circular motion combined with a constant upward velocity. Assume a bird completes a circle of radius 6.00 m every 5.00 s and rises vertically at a constant rate of 3.00 m/s. Determine:(a) The speed of the bird relative to the ground;(b) The b
Answer Preview: Identify The velocity has a horizontal tangential component and a vertical …

, Chapter: 4 -Problem: 19 >> A person can dive into water from a height of 10 m without injury, but a person who jumps off the roof of a 10-m-tall building and lands on a concrete street is likely to be seriously injured. Why is there a difference?
Answer Preview: You have the same speed just before impac…

, Chapter: 16 -Problem: 24 >> If you are riding in a supersonic aircraft, what do you hear? Explain. In particular, do you hear a continuous sonic boom? Why or why not?
Answer Preview: The air inside the plane is moving with the plane so sound travels relative t…

, Chapter: 19 -Problem: 9 >> Imagine a gas made up entirely of negatively charged electrons. Like charges repel, so the electrons exert repulsive forces on each other. Would you expect that the temperature of such a gas would rise, fall, or stay the same in a free expansion? Why?
Answer Preview: In the expansion the repulsive …

, Chapter: 14 -Problem: 33 >> The point of the needle of a sewing machine moves in SHM along the x-axis with a frequency of 2.5 Hz. At t = 0 its position and velocity components are +1.1 cm –15 cm/s. and respectively.(a) Find the acceleration component of the needle at t = 0.(b) Write equations giving the position, velocity, and acceleration components of the point as a function of time.
Answer Preview: Identify For SHM Apply Eqs 14 13 14 15 and 14 16 with A and fr…

, Chapter: 15 -Problem: 15 >> Can a standing wave be produced on a string by superposing two waves traveling in opposite directions with the same frequency but different amplitudes? Why or why not? Can a standing wave be produced by superposing two waves traveling in opposite directions with different frequencies but the same amplitude? Why or why not?
Answer Preview: No a standing wave is not produced if the two waves dont have the sam…

, Chapter: 28 -Problem: 16 >> Why should the permeability of a paramagnetic material be expected to decrease with increasing temperature?
Answer Preview: Smaller permeability means it is more difficult for an external mag…

, Chapter: 7 -Problem: 29 >> The maximum energy that a bone can absorb without breaking depends on its characteristics, such as its cross-sectional area and its elasticity. For healthy human leg bones of approximately 6.0 cm2 cross-sectional area, this energy has been experimentally measured to be about 200 J. (a) From approximately what maximum height could a 60-kg person jumpand land rigidly upright on both feet without bre
Answer Preview: Identify The potential energy is transformed into ki…

, Chapter: 25 -Problem: 52 >> An overhead transmission cable for electrical power is 2000 m long and consists of two parallel copper wires, each encased in insulating material. A short circuit has developed somewhere along the length of the cable where the insulation has worn thin and the two wires are in contact. As a power-company employee, you must locate the short so that repair crews can be sent to that location. Both end
Answer Preview: IDENTIFY and SET UP Use R L A and V RI Call x the dista…

, Chapter: 10 -Problem: 89 >> You have one object of each of these shapes, all with mass 0.840 kg: a uniform solid cylinder, a thin-walled hollow cylinder, a uniform solid sphere, and a thin-walled hollow sphere. You release each object from rest at the same vertical height h above the bottom of a long wooden ramp that is inclined at 35.0ofrom the horizontal. Each object rolls without slipping down the ramp. You measure the ti
Answer Preview: IDENTIFY All the objects have the same mass and start from rest at the same height h They roll without slipping so their mechanical energy is conserved Newtons second law in its linear and rotational …

, Chapter: 18 -Problem: 30 >> In addition to the normal cooking directions printed on the back of a box of rice, there are also “high-altitude directions.” The only difference is that the “high altitude directions” suggest increasing the cooking time and using a greater volume of boiling water in which to cook the rice. Why should the directions depend on the altitude in this way?
Answer Preview: The boiling point temperature …

, Chapter: 9 -Problem: 69 >> A frictionless pulley has the shape of a uniform solid disk of mass 2.50 kg and radius 20.0 cm. A 1.50-kg stone is attached to a very light wire that is wrapped around the rim of the pulley (Fig. E9.47), and the system is released from rest.(a) How far must the stone fall so that the pulley has 4.50 J of kinetic energy?(b) What percent of the total kinetic energy does the pulley have?Figure 9.47:
Answer Preview: Identify Apply conservation of energy to the system of stone plus pulley v r rela…

, Chapter: 12 -Problem: 10 >> Which has a greater buoyant force on it: a 25-cm3 piece of wood floating with part of its volume above water or a 25-cm3 piece of submerged iron? Or, must you know their masses before you can answer? Explain.
Answer Preview: Assume that in each case the liquid is the same The buoyant …

, Chapter: 26 -Problem: 16 >> Identical light bulbs A, B, and C are connected as shown in Fig. Q26.16. When the switch S is closed, bulb C goes out. Explain why. What happens to the brightness of bulbs A and B? Explain. Figure Q26.16
Answer Preview: With the switch open the three bulbs are connected in …

, Chapter: 35 -Problem: 53 >> Short-wave radio antennas A and B are connected to the same transmitter and emit coherent waves in phase and with the same frequency f. You must determine the value of f and the placement of the antennas that produce a maximum intensity through constructive interference at a receiving antenna that is located at point P, which is at the corner of your garage. First you place antenna A at a point 24
Answer Preview: IDENTIFY The wave from A travels a longer distance than the wave from B to reach point P so the two …

, Chapter: 7 -Problem: 76 >> A sled with rider having a combined mass of 125 kg travels over the perfectly smooth icy hill shown in Fig. 7.68. How far does the sled land from the foot of the cliff?Figure 7.68: Transcribed Image Text: 11.0m Cliff 22.5 m/s
Answer Preview: Identify Mechanical energy is conserved on the hill which gives us the …

, Chapter: 4 -Problem: 37 >> In a head-on collision between a compact 1000-kg car and a large 2500-kg car, which one experiences the greater force? Explain. Which one experiences the greater acceleration? Explain why. Why are passengers in the small car more likely to be injured than those in the large car, even when the two car bodies are equally strong?
Answer Preview: By Newtons 3rd law the force the large car exerts on the small car equa…

, Chapter: 16 -Problem: 17 >> A large church has part of the organ in the front of the church and part in the back. A person walking rapidly down the aisle while both segments are playing at once reports that the two segments sound out of tune. Why?
Answer Preview: The person is moving toward one source and it…

, Chapter: 19 -Problem: 17 >> The prevailing winds on the Hawaiian island of Kauai blow from the northeast. The winds cool as they go up the slope of Mt. Waialeale (elevation 1523 m), causing water vapor to condense and rain to fall. There is much more precipitation at the summit than at the base of the mountain. In fact, Mt. Waialeale is the rainiest spot on earth, averaging 11.7 m of rainfall a year. But what makes the winds
Answer Preview: The air does positive work t…

, Chapter: 14 -Problem: 59 >> A mass m is attached to a spring of force constant 75 N m and allowed to oscillate. Figure E14.34 shows a graph of its velocity as a function of time t. Find(a) The period,(b) The frequency,(c) The angular frequency of this motion.(d) What is the amplitude (in cm), and at what times does the mass reach this position?(e) Find the maximum acceleration of the mass and the times at which it occurs.(f)
Answer Preview: Identify The velocity is a sinusoidal function From the graph we can r…

, Chapter: 15 -Problem: 7 >> Is it possible to have a longitudinal wave on a stretched string? Why or why not? Is it possible to have a transverse wave on a steel rod? Again, why or why not? If your answer is yes in either case, explain how you would create such a wave.
Answer Preview: The answer is yes to both questions All that is required is t…

, Chapter: 28 -Problem: 19 >> The magnetic susceptibility of paramagnetic materials is quite strongly temperature dependent, but that of diamagnetic materials is nearly independent of temperature. Why the difference?
Answer Preview: Paramagnetism is due to partial alignment of the magnetic moments of individual atoms and this …

, Chapter: 34 -Problem: 53 >> Ordinary glasses are worn in front of the eye and usually 2.0 cm in front of the eyeball. Suppose that the person in Exercise 34.52 prefers ordinary glasses to contact lenses. What focal length lenses are needed to correct his vision, and what is their power in diopters?
Answer Preview: IDENTIFY and SET UP For an object 25 0 cm from the …

, Chapter: 6 -Problem: 116 >> All birds, independent of their size, must maintain a power output of 10–25 watts per kilogram of body mass in order to fly by flapping their wings.(a) The Andean giant hummingbird (Patagona gigas) has mass 70 g and flaps its wings 10 times per second while hovering. Estimate the amount of work done by such a hummingbird in each wingbeat.(b) A 70-kg athlete can maintain a power output of 1.4 kW fo
Answer Preview: Identify and Set Up W Pt Execute a The hummingbird produces energy at a rate of 07 Js to 175 Js …

, Chapter: 25 -Problem: 75 >> The voltage drop Vabacross each of resistors A and B was measured as a function of the current I in the resistor. The results are shown in the table: (a) For each resistor, graph Vab as a function of I and graph the resistance R = Vab/I as a function of I.(b) Does resistor A obey Ohm€™s law? Explain.(c) Does resistor B obey Ohm€™s law? Explain.(d) What is the power dissipated in A if it is connect
Answer Preview: IDENTIFY According to Ohms law R V ab I constant and a graph of V ab versus I will be a straight lin…

, Chapter: 8 -Problem: 108 >> What is the average force the fish exerts on the drop of water?(a) 0.00015 N;(b) 0.00075 N;(c) 0.075 N;(d) 0.15 N. Archerfish are tropical fish that hunt by shooting drops of water from their mouths at insects above the water’s surface to knock them into the water, where the fish can eat them. A 65-g fish at rest just at the surface of the water can expel a 0.30-g drop of water in a short burst of
Answer Preview: IDENTIFY and SET UP J F av t p EXECUTE F av p …

, Chapter: 19 -Problem: 52 >> A certain ideal gas has molar heat capacity at constant volume CV . A sample of this gas initially occupies a volume V0 at pressure p0 and absolute temperature T0 . The gas expands isobarically to a volume 2V0 and then expands further adiabatically to a final volume 4V0.(a) Draw a pV-diagram for this sequence of processes.(b) Compute the total work done by the gas for this sequence of processes.(c
Answer Preview: IDENTIFY For constant pressure W pV For an adiabatic process of an ideal …

, Chapter: 9 -Problem: 71 >> A thin, light wire is wrapped around the rim of a wheel, as shown in Fig. E9.49. The wheel rotates without friction about a stationary horizontal axis that passes through the center of the wheel. The wheel is a uniform disk with radius R = 0.280 m. An object of mass m = 4.20 kg is suspended from the free end of the wire. The system is released from rest and the suspended object descends with const
Answer Preview: Identify With constant acceleration we can use kinematics to find the speed of …

, Chapter: 15 -Problem: 3 >> What kinds of energy are associated with waves on a stretched string? How could you detect such energy experimentally?
Answer Preview: There is kinetic energy of the moving strin…

, Chapter: 28 -Problem: 83 >> The solenoid is removed from the enclosure and then used in a location where the earth’s magnetic field is 50 µT and points horizontally. A sample of bacteria is placed in the center of the solenoid, and the same current is applied that produced a magnetic field of 150 µT in the lab. Describe the field experienced by the bacteria: The field(a) Is still 150 µT;(b) Is now 200 µT;(c) Is between 100 a
Answer Preview: IDENTIFY and SET UP The enclosure is no longer present to shield the solenoid from the e…

, Chapter: 37 -Problem: 25 >> A source of electromagnetic radiation is moving in a radial direction relative to you. The frequency you measure is 1.25 times the frequency measured in the rest frame of the source. What is the speed of the source relative to you? Is the source moving toward you or away from you?
Answer Preview: IDENTIFY There is a Doppler effect in the frequency of the radiation …

, Chapter: 6 -Problem: 106 >> Your cat “Ms.” (mass 7.00 kg) is trying to make it to the top of a frictionless ramp 2.00 m long and inclined upward 30.0º at above the horizontal. Since the poor cat can’t get any traction on the ramp, you push her up the entire length of the ramp by exerting a constant 100-N force parallel to the ramp. If Ms. takes a running start so that she is moving at 2.40 m/s at the bottom of the ramp, what
Answer Preview: Identify Apply W tot K 2 K 1 to the cat Set Up Let point 1 be …

, Chapter: 4 -Problem: 5 >> If the two ends of a rope in equilibrium are pulled with forces of equal magnitude and opposite directions, why isn’t the total tension in the rope zero?
Answer Preview: Let the force applied to each end have …

, Chapter: 10 -Problem: 96 >> A doubling of the torque produces a greater angular acceleration. Which of the following would do this, assuming that the tension in the rope doesn€™t change?(a) Increasing the pulley diameter by a factor of ˆš2;(b) Increasing the pulley diameter by a factor of 2;(c) Increasing the pulley diameter by a factor of 4;(d) Decreasing the pulley diameter by a factor of ˆš2. The moment of inertia of the
Answer Preview: IDENTIFY and SET UP The torque is the product of the force times the lever a…

, Chapter: 19 -Problem: 7 >> You hold an inflated balloon over a hot-air vent in your house and watch it slowly expand. You then remove it and let it cool back to room temperature. During the expansion, which was larger: the heat added to the balloon or the work done by the air inside it? Explain. (Assume that air is an ideal gas.) Once the balloon has returned to room temperature, how does the net heat gained or lost by the
Answer Preview: U Q W If we treat the air inside the balloon as an ideal gas U for the gas dep…

, Chapter: 12 -Problem: 119 >> A cylindrical container of an in-compressible liquid with density ρ rotates with constant angular speed ω about its axis of symmetry, which we take to be the y-axis (Fig. P12.86).(a) Show that the pressure at a given height within the fluid increases in the radial direction (outward from the axis of rotation) according to ˆ‚p/ˆ‚r = ÏÏ‰2r.(b) Integrate this partial differential equation to find
Answer Preview: Identify Apply to a small fluid element located a distance r from the axis S…

, Chapter: 14 -Problem: 92 >> Two springs with the same unstretched length but different force constants k1and k2are attached to a block with mass m on a level, frictionless surface. Calculate the effective force constant keffin each of the three cases (a), (b), and (c) depicted in Fig. P14.92. (The effective force constant is defined by ΣFx= -keffx.) (d) An object with mass m, suspended from a uniform spring with a force con
Answer Preview: IDENTIFY In each situation imagine the mass moves a distance x the springs move distances x 1 …

, Chapter: 37 -Problem: 12 >> When a monochromatic light source moves toward an observer, its wavelength appears to be shorter than the value measured when the source is at rest. Does this contradict the hypothesis that the speed of light is the same for all observers? Explain.
Answer Preview: No The speed of light is the same for all observer…

, Chapter: 7 -Problem: 35 >> Tendons are strong elastic fibers that attach muscles to bones. To a reasonable approximation, they obey Hooke’s law. In laboratory tests on a particular tendon, it was found that, when a 250-g object was hung from it, the tendon stretched 1.23 cm.(a) Find the force constant of this tendon in N/m.(b) Because of its thickness, the maximum tension this tendon can support without rupturing is 138 N.
Answer Preview: Identify We treat the tendon like a spring and apply Hookes law to it Knowing the force stretc…

, Chapter: 4 -Problem: 20 >> Why are cars designed to crumple in front and back for safety? Why not for side collisions and rollovers?
Answer Preview: The crumpling increases the stopping distance …

, Chapter: 16 -Problem: 3 >> Would you expect the pitch (or frequency) of an organ pipe to increase or decrease with increasing temperature? Explain.
Answer Preview: The wave speed increases with temperature so …

, Chapter: 19 -Problem: 21 >> When a gas expands adiabatically, it does work on its surroundings. But if there is no heat input to the gas, where does the energy come from to do the work?
Answer Preview: The energy comes …

, Chapter: 13 -Problem: 1 >> A student wrote: “The only reason an apple falls downward to meet the earth instead of the earth rising upward to meet the apple is that the earth is much more massive and so exerts a much greater pull.” Please comment.
Answer Preview: The force the earth exerts on the apple …

, Chapter: 29 -Problem: 13 >> A metal ring is oriented with the plane of its area perpendicular to a spatially uniform magnetic field that increases at a steady rate. If the radius of the ring is doubled, by what factor do(a) The emf induced in the ring and(b) The electric field induced in the ring change?
Answer Preview: a where r is the radius of the ring I…

, Chapter: 34 -Problem: 16 >> The focal length of a simple lens depends on the color (wavelength) of light passing through it. Why? Is it possible for a lens to have a positive focal length for some colors and negative for others? Explain.
Answer Preview: The focal length of a thin lens is given by Eq 34 19 The refractive index n of the lens mat…

, Chapter: 13 -Problem: 101 >> A 5000-kg spacecraft is in a circular orbit 2000 km above the surface of Mars. How much work must the spacecraft engines perform to move the spacecraft to a circular orbit that is 4000 km above the surface?
Answer Preview: Identify and Set Up Apply conservation of energy Eq 713 and solve fo…

, Chapter: 4 -Problem: 21 >> When a string barely strong enough lifts a heavy weight, it can lift the weight by a steady pull; but if you jerk the string, it will break. Explain in terms of Newton’s laws of motion.
Answer Preview: For a steady pull the acceleration is small and the tension in …

, Chapter: 11 -Problem: 94 >> His body is again leaning back at 30.0oto the vertical, but now the height at which the rope is held above but still parallel to the ground is varied. The tension in the rope in front of the competitor (T1) is measured as a function of the shortest distance between the rope and the ground (the holding height). Tension T1is found to decrease as the holding height increases. What could explain this
Answer Preview: IDENTIFY and SET UP Apply Fl EXECUTE The moment arm for T 1 has increase…

, Chapter: 18 -Problem: 80 >> A steel cylinder with rigid walls is evacuated to a high degree of vacuum; you then put a small amount of helium into the cylinder. The cylinder has a pressure gauge that measures the pressure of the gas inside the cylinder. You place the cylinder in various temperature environments, wait for thermal equilibrium to be established, and then measure the pressure of the gas. You obtain these results:
Answer Preview: IDENTIFY and SET UP For an ideal gas its pressure approaches zero as its temperatu…

, Chapter: 14 -Problem: 67 >> At the end of a ride at a winter-theme amusement park, a sleigh with mass 250 kg (including two passengers) slides without friction along a horizontal, snow-covered surface. The sleigh hits one end of a light horizontal spring that obeys Hooke’s law and has its other end attached to a wall. The sleigh latches onto the end of the spring and subsequently moves back and forth in SHM on the end of the
Answer Preview: IDENTIFY and SET UP For SHM we know that v max A and a max 2 A EXECUTE a J…

, Chapter: 27 -Problem: 85 >> The large magnetic fields used in MRI can produce forces on electric currents within the human body. This effect has been proposed as a possible method for imaging €œbiocurrents€ flowing in the body, such as the current that flows in individual nerves. For a magnetic field strength of 2 T, estimate the magnitude of the maximum force on a 1-mm-long segment of a single cylindrical nerve that has a
Answer Preview: IDENTIFY and SET UP Model the nerve as a current carry…

, Chapter: 34 -Problem: 24 >> You take a lens and mask it so that light can pass through only the bottom half of the lens. How does the image formed by the masked lens compare to the image formed before 32 masking?
Answer Preview: Each section of a lens forms the entire image The image forme…

, Chapter: 2 -Problem: 54 >> Two cars, A and B, move along the x-axis. Figure E2.32 is a graph of the positions of A and B versus time.Figure E2.32(a) In motion diagrams (like Figs. 2.13b and 2.14b), show the position, velocity, and acceleration of each of the two cars at t = 0, t = 1 s, and t = 3 s.(b) At what time(s), if any, do A and B have the same position?(c) Graph velocity versus time for both A and B.(d) At what time(
Answer Preview: v x t is the slope of the x versus t graph Car B moves with constant speed and zero acceleration Car …

, Chapter: 4 -Problem: 16 >> Students sometimes say that the force of gravity on an object is 9.8 m/s2. What is wrong with this view?
Answer Preview: The quantity g 9 8 m s 2 is the acceleration pro…

, Chapter: 16 -Problem: 77 >> If the deepest structure you wish to image is 10.0 cm from the transducer, what is the maximum number of pulses per second that can be emitted?(a) 3850;(b) 7700;(c) 15,400;(d) 1,000,000. A typical ultrasound transducer used for medical diagnosis produces a beam of ultrasound with a frequency of 1.0 MHz. The beam travels from the transducer through tissue and partially reflects when it encounters d
Answer Preview: IDENTIFY and SET UP The time between pulses is limited by the time for the wave to travel from the …

, Chapter: 18 -Problem: 10 >> Use the concepts of the kinetic-molecular model to explain:(a) why the pressure of a gas in a rigid container increases as heat is added to the gas and(b) why the pressure of a gas increases as we compress it, even if we do not change its temperature.
Answer Preview: a Adding heat to the gas increases the average kine…

, Chapter: 15 -Problem: 4 >> The amplitude of a wave decreases gradually as the wave travels down a long, stretched string. What happens to the energy of the wave when this happens?
Answer Preview: The energy in the wave decre…

, Chapter: 26 -Problem: 88 >> Cell membranes across a wide variety of organisms have a capacitance per unit area of 1 µF/cm2. For the electrical signal in a nerve to propagate down the axon, the charge on the membrane “capacitor” must change. What time constant is required when the ion channels are open?(a) 1 µs;(b) 10 µs;(c) 100 µs;(d) 1 ms. The portion of a nerve cell that conducts signals is called an axon. Many of the elec
Answer Preview: IDENTIFY and SET UP RC The resistance is 1 10 11 C is the capacitance …

, Chapter: 35 -Problem: 30 >> A researcher measures the thickness of a layer of benzene (n = 1.50) floating on water by shining monochromatic light onto the film and varying the wavelength of the light. She finds that light of wavelength 575 nm is reflected most strongly from the film. What does she calculate for the minimum thickness of the film?
Answer Preview: IDENTIFY and SET UP Since the film reflects 575 nm strongly we must have const…

, Chapter: 4 -Problem: 64 >> Human Biomechanics. The fastest served tennis ball, served by “Big Bill” Tilden in 1931, was measured at 73.14 m/s. The mass of a tennis ball is 57 g, and the ball is typically in contact with the tennis racquet for 30.0 ms, with the ball starting from rest. Assuming constant acceleration,(a) What force did Big Bill’s tennis racquet exert on the tennis ball if he hit it essentially horizontally?(b
Answer Preview: Identify Kinematics will give us the balls acceleration and Newtons second law will gi…

, Chapter: 25 -Problem: 79 >> What is the best explanation for the behavior exhibited in the data? (a) Longer threads can carry more current than shorter threads do and so make better electrical conductors. (b) The thread stops being a conductor when it is stretched to 13 mm, due to breaks that occur in the thin coating. (c) As the thread is stretched, the coating thins and its resistance increases; as the thread is relaxed, t
Answer Preview: IDENTIFY and SET UP R L A EXECUTE From the equation R L A if we double the length …

, Chapter: 16 -Problem: 10 >> If the pressure amplitude of a sound wave is halved, by what factor does the intensity of the wave decrease? By what factor must the pressure amplitude of a sound wave be increased in order to increase the intensity by a factor of 16? Explain.
Answer Preview: According to Eq 16 14 the intensity is proportional to the square of the pres…

, Chapter: 17 -Problem: 116 >> You place 35 g of this cryoprotectant at 22°C in contact with a cold plate that is maintained at the boiling temperature of liquid nitrogen (77 K). The cryoprotectant is thermally insulated from everything but the cold plate. Use the values in the table to determine how much heat will be transferred from the cryoprotectant as it reaches thermal equilibrium with the cold plate. (a) 1.5 × 104 J;(b)
Answer Preview: IDENTIFY The cryoprotectant must cool from 22C to 2…

, Chapter: 14 -Problem: 15 >> Why do short dogs (like Chihuahuas) walk with quicker strides than do tall dogs (like Great Danes)?
Answer Preview: The period of oscillation of the short…

, Chapter: 29 -Problem: 10 >> A square conducting loop is in a region of uniform, constant magnetic field. Can the loop be rotated about an axis along one side and no emf be induced in the loop? Discuss, in terms of the orientation of the rotation axis relative to the magnetic-field direction.
Answer Preview: If the axis of rotation is parallel t…

, Chapter: 36 -Problem: 8 >> A rainbow ordinarily shows a range of colors (see Section 33.4). But if the water droplets that form the rainbow are small enough, the rainbow will appear white. Explain why, using diffraction ideas. How small do you think the raindrops would have to be for this to occur?
Answer Preview: The raindrop acts as an aperture If the drop is sm…

, Chapter: 7 -Problem: 57 >> A 15.0-kg stone slides down a snow-covered hill (Fig. P7.49), leaving point A with a speed of 10.00 m/s. There is no friction on the hill between points A and B, but there is friction on the level ground at the bottom of the hill, between B and the wall. After entering the rough horizontal region, the stone travels 100 m and then runs into a very long, light spring with force constant 2.00 N/m. Th
Answer Preview: Identify Apply Eq 77 to the motion of the stone Set up a Let point 1 be point A and point 2 be poin…

, Chapter: 4 -Problem: 8 >> Some people say that the “force of inertia” (or “force of momentum”) throws the passengers forward when a car brakes sharply. What is wrong with this explanation?
Answer Preview: It is the absence of sufficient force directed o…

, Chapter: 16 -Problem: 55 >> A stationary police car emits a sound of frequency 1200 Hz that bounces off a car on the highway and returns with a frequency of 1250 Hz. The police car is right next to the highway, so the moving car is traveling directly toward or away from it.(a) How fast was the moving car going? Was it moving toward or away from the police car?(b) What frequency would the police car have received if it had be
Answer Preview: IDENTIFY Apply the Doppler shift formulas We first treat the stationary police car as th…

, Chapter: 17 -Problem: 16 >> The climate of regions adjacent to large bodies of water (like the Pacific and Atlantic coasts) usually features a narrower range of temperature than the climate of regions far from large bodies of water (like the prairies). Why?
Answer Preview: The body of water has a large value …

, Chapter: 13 -Problem: 21 >> As part of their training before going into orbit, astronauts ride in an airliner that is flown along the same parabolic trajectory as a freely falling projectile. Explain why this gives the same experience of apparent weightlessness as being in orbit.
Answer Preview: The only force on the …

, Chapter: 29 -Problem: 12 >> In many magnetic resonance imaging (MRI) systems, the magnetic field is produced by a superconducting magnet that must be kept cooled below the superconducting transition temperature. If the cryogenic cooling system fails, the magnet coils may lose their superconductivity and the strength of the magnetic field will rapidly decrease, or quench. The dissipation of energy as heat in the now-non super
Answer Preview: IDENTIFY and SET UP Use Faradays law Th…

, Chapter: 36 -Problem: 71 >> When the light is passed through the bottom of the sample container, the interference maximum is observed to be at 41°; when it is passed through the top, the corresponding maximum is at 37°. What is the best explanation for this observation?(a) The microspheres are more tightly packed at the bottom, because they tend to settle in the suspension.(b) The microspheres are more tightly packed at the
Answer Preview: IDENTIFY and SET UP For an interference maxima 2d sin m 0 n so sin 1 d If d is smaller …

, Chapter: 6 -Problem: 93 >> When a car is hit from behind, its passengers undergo sudden forward acceleration, which can cause a severe neck injury known as whiplash. During normal acceleration, the neck muscles play a large role in accelerating the head so that the bones are not injured. But during a very sudden acceleration, the muscles do not react immediately because they are flexible, so most of the accelerating force i
Answer Preview: Identify The initial kinetic energy of the head is abso…

, Chapter: 4 -Problem: 6 >> You tie a brick to the end of a rope and whirl the brick around you in a horizontal circle. Describe the path of the brick after you suddenly let go of the rope.
Answer Preview: Before you let go the velocity of the brick is tangen…

, Chapter: 5 -Problem: 26 >> A ball is dropped from rest and feels air resistance as it falls. Which of the graphs in Fig. Q5.26 best represents its vertical velocity component as a function of time?Figure Q5.26 Transcribed Image Text: (a) (c) (d) (e) (b)
Answer Preview: Dropped from rest means the initial speed …

, Chapter: 17 -Problem: 94 >> A thirsty nurse cools a 2.00-L bottle of a soft drink (mostly water) by pouring it into a large aluminum mug of mass 0.257 kg and adding 0.120 kg of ice initially at -15.0°C. If the soft drink and mug are initially at 20.0°C, what is the final temperature of the system, assuming that no heat is lost?
Answer Preview: IDENTIFY The amount of heat lost by the soft drink and mug is equal to the heat gained by the ice Th…

, Chapter: 13 -Problem: 11 >> A planet is moving at constant speed in a circular orbit around a star. In one complete orbit, what is the net amount of work done on the planet by the star’s gravitational force: positive, negative, or zero? What if the planet’s orbit is an ellipse, so that the speed is not constant? Explain your answers.
Answer Preview: For a circular orbit the work done is zero We can see this in either of two ways …

, Chapter: 27 -Problem: 1 >> Can a charged particle move through a magnetic field without experiencing any force? If so, how? If not, why not?
Answer Preview: There is no force when v ve…

, Chapter: 34 -Problem: 12 >> In Example 34.4 (Section 34.2), there appears to be an ambiguity for the case s = 10 cm as to whether s' is +? or -? and whether the image is erect or inverted. How is this resolved? Or is it?
Answer Preview: For s exactly equal to f the reflected rays are parallel to the axis and there is n…

, Chapter: 13 -Problem: 107 >> A shaft is drilled from the surface to the center of the earth (see Fig. 13.24). As in Example 13.10 (Section 13.6), make the unrealistic assumption that the density of the earth is uniform. With this approximation, the gravitational force on an object with mass m, that is inside the earth at a distance r from the center, has magnitude (as shown in Example 13.10) and points toward the center of th
Answer Preview: Identify Compare F E to Hookes law Set Up The earth has mass and radius Execute a Fo…

, Chapter: 3 -Problem: 14 >> In a rainstorm with a strong wind, what determines the best position in which to hold an umbrella?
Answer Preview: Hold the umbrella at an angle …

, Chapter: 8 -Problem: 74 >> Block B (mass 4.00 kg) is at rest at the edge of a smooth platform, 2.60 m above the floor. Block A (mass 2.00 kg) is sliding with a speed of 8.00 m/s along the platform toward block B. A strikes B and rebounds with a speed of 2.00 m/s. The collision projects B horizontally off the platform. What is the speed of B just before it strikes the floor?
Answer Preview: IDENTIFY An inelastic collision the objects stick together occurs during which momentum is conserved …

, Chapter: 19 -Problem: 18 >> Applying the same considerations as in Question Q19.17, explain why the island of Niihau, a few kilometers to the southwest of Kauai, is almost a desert and farms there need to be irrigated. Data from Q19.17The prevailing winds on the Hawaiian island of Kauai blow from the northeast. The winds cool as they go up the slope of Mt. Waialeale (elevation 1523 m), causing water vapor to condense and rai
Answer Preview: As the air moves downward on the smo…

, Chapter: 13 -Problem: 17 >> At what point in an elliptical orbit is the acceleration maximum? At what point is it minimum? Justify your answers.
Answer Preview: The acceleration is greatest when the …

, Chapter: 28 -Problem: 10 >> What are the relative advantages and disadvantages of Ampere’s law and the law of Biot and Savart for practical calculations of magnetic fields?
Answer Preview: The Biot Savart law applies directly to an infinitesimal current element In …

, Chapter: 35 -Problem: 7 >> Could the Young two-slit interference experiment be performed with gamma rays? If not, why not? If so, discuss differences in the experimental design compared to the experiment with visible light.
Answer Preview: In principle yes But the wavelengths of ga…

, Chapter: 2 -Problem: 63 >> A typical male sprinter can maintain his maximum acceleration for 2.0 s and his maximum speed is 10 m/s. After reaching this maximum speed, his acceleration becomes zero and then he runs at constant speed. Assume that his acceleration is constant during the first 2.0 s of the race, that he starts from rest, and that he runs in a straight line.(a) How far has the sprinter run when he reaches his ma
Answer Preview: Identify The sprinters acceleration is constant for the first 20 s …

, Chapter: 25 -Problem: 82 >> In another experiment, a piece of the web is suspended so that it can move freely. When either a positively charged object or a negatively charged object is brought near the web, the thread is observed to move toward the charged object. What is the best interpretation of this observation? The web is (a) A negatively charged conductor; (b) A positively charged conductor; (c) Either a positively or
Answer Preview: IDENTIFY and SET UP An electrically neutral conductor contains equal amounts of posit…

, Chapter: 16 -Problem: 34 >> Small speakers A and B are driven in phase at 725 Hz by the same audio oscillator. Both speakers start out 4.50 m from the listener, but speaker A is slowly moved away (Fig. E16.34).(a) At what distance d will the sound from the speakers first produce destructive interference at the listener€™s location?(b) If A is moved even farther away than in part (a), at what distance d will the speakers next
Answer Preview: IDENTIFY and SET UP The path difference for the two sources is d Fo…

, Chapter: 18 -Problem: 14 >> The temperature of an ideal gas is directly proportional to the average kinetic energy of its molecules. If a container of ideal gas is moving past you at 2000 m/s, is the temperature of the gas higher than if the container was at rest? Explain your reasoning.
Answer Preview: Temperature is related to the a…

, Chapter: 12 -Problem: 26 >> In a store-window vacuum cleaner display, a table-tennis ball is suspended in midair in a jet of air blown from the outlet hose of a tank type vacuum cleaner. The ball bounces around a little but always moves back toward the center of the jet, even if the jet is tilted from the vertical. How does this behavior illustrate Bernoulli’s equation?
Answer Preview: The pressure is le…

, Chapter: 28 -Problem: 9 >> A current was sent through a helical coil spring. The spring contracted, as though it had been compressed. Why?
Answer Preview: Adjacent turns of …

, Chapter: 35 -Problem: 60 >> The professor once again returns the apparatus to its original setting, but now she adjusts the oscillator to produce sound waves of half the original frequency. What happens?(a) The students who originally heard a loud tone again hear a loud tone, and the students who originally heard nothing still hear nothing. (b) The students who originally heard a loud tone now hear nothing, and the students
Answer Preview: IDENTIFY and SET UP Since v f reducing the frequency half increases the wavelength by a factor of 2 …

, Chapter: 13 -Problem: 89 >> A spacecraft is to be launched from the surface of the earth so that it will escape from the solar system altogether.(a) Find the speed relative to the center of the earth with which the spacecraft must be launched. Take into consideration the gravitational effects of both the earth and the sun, and include the effects of the earth€™s orbital speed, but ignore air resistance.(b) The rotation of th
Answer Preview: Identify At the escape speed E K U 0 Set Up At the surface of the earth the satellite is a distance …

, Chapter: 2 -Problem: 13 >> The official€™s truck in Fig. 2.2 is at x1= 277 m at t1= 16.0 s and is at x2= 19 m at t2= 25.0 s.(a) Sketch two different possible x-t graphs for the motion of the truck.(b) Does the average velocity vav-x during the time interval from t1 to t2 have the same value for both of your graphs? Why or why not?Fig. 2.2  Transcrib
Answer Preview: a Two possible x t graphs for the motion of the truck are sk…

, Chapter: 16 -Problem: 6 >> In a popular and amusing science demonstration, a person inhales helium and then his voice becomes high and squeaky. Why does this happen? (Warning: Inhaling too much helium can cause unconsciousness or death.)
Answer Preview: The speed of sound in helium is muc…

, Chapter: 17 -Problem: 114 >> Consider a poor lost soul walking at 5 km/h on a hot day in the desert, wearing only a bathing suit. This person’s skin temperature tends to rise due to four mechanisms:(i) Energy is generated by metabolic reactions in the body at a rate of 280 W, and almost all of this energy is converted to heat that flows to the skin;(ii) Heat is delivered to the skin by convection from the outside air at a rat
Answer Preview: IDENTIFY The rate in iv is given by H net e A T 4 T 4 s with T 309 K and Ts 320 K The heat absorbed …

, Chapter: 13 -Problem: 44 >> There is strong evidence that Europa, a satellite of Jupiter, has a liquid ocean beneath its icy surface. Many scientists think we should land a vehicle there to search for life. Before launching it, we would want to test such a lander under the gravity conditions at the surface of Europa. One way to do this is to put the lander at the end of a rotating arm in an orbiting earth satellite. If the a
Answer Preview: IDENTIFY Use g G m E r 2 to calculate g for Europa The accelerati…

, Chapter: 27 -Problem: 22 >> In a cyclotron, the orbital radius of protons with energy 300 keV is 16.0 cm. You are redesigning the cyclotron to be used instead for alpha particles with energy 300 keV. An alpha particle has charge q = +2e and mass m = 6.64 × 10-27 kg. If the magnetic field isn’t changed, what will be the orbital radius of the alpha particles?
Answer Preview: IDENTIFY An alpha particle has twice as much charge and …

, Chapter: 36 -Problem: 15 >> Why is a diffraction grating better than a two-slit setup for measuring wavelengths of light?
Answer Preview: With a grating the bright fringes are …

, Chapter: 3 -Problem: 61 >> A toy rocket is launched with an initial velocity of 12.0 m s in the horizontal direction from the roof of a 30.0-m-tall building. The rocket’s engine produces a horizontal acceleration of (1.60 m/s3)t, in the same direction as the initial velocity, but in the vertical direction the acceleration is g, downward. Air resistance can be neglected. What horizontal distance does the rocket travel before
Answer Preview: Identify Find the horizontal distance a rocket moves if it h…

, Chapter: 25 -Problem: 81 >> What is the maximum current that flows in the thread during this experiment if the voltage source is a 9-V battery?(a) About 1 A;(b) About 0.1 A;(c) About 1 µA;(d) about 1 nA. Some types of spiders build webs that consist of threads made of dry silk coated with a solution of a variety of compounds. This coating leaves the threads, which are used to capture prey, hygroscopic that is, they attract w
Answer Preview: IDENTIFY and SET UP Apply Ohms law V RI The minimum res…

, Chapter: 16 -Problem: 13 >> A small metal band is slipped onto one of the tines of a tuning fork. As this band is moved closer and closer to the end of the tine, what effect does this have on the wavelength and frequency of the sound the tine produces? Why?
Answer Preview: The added mass slows the vibration of the tine …

, Chapter: 19 -Problem: 1 >> For the following processes, is the work done by the system (defined as the expanding or contracting gas) on the environment positive or negative?(a) Expansion of the burned gasoline–air mixture in the cylinder of an automobile engine;(b) Opening a bottle of champagne;(c) Filling a scuba tank with compressed air;(d) Partial crumpling of a sealed, empty water bottle as you drive from the mountains
Answer Preview: a Positive volume of the gas in…

, Chapter: 12 -Problem: 17 >> At a certain depth in an incompressible liquid, the absolute pressure is p. At twice this depth, will the absolute pressure be equal to 2p, greater than 2p, or less than 2p? Justify your answer.
Answer Preview: The pressure at depth h in an incompressible fluid is …

, Chapter: 28 -Problem: 33 >> The magnetic field around the head has been measured to be approximately 3.0 × 10-8 G. Although the currents that cause this field are quite complicated, we can get a rough estimate of their size by modeling them as a single circular current loop 16 cm (the width of a typical head) in diameter. What is the current needed to produce such a field at the center of the loop?
Answer Preview: IDENTIFY We can model the current in the brain as a …

, Chapter: 35 -Problem: 12 >> In using the superposition principle to calculate intensities in interference patterns, could you add the intensities of the waves instead of their amplitudes? Explain.
Answer Preview: No amplitudes must be added For electro…

, Chapter: 2 -Problem: 33 >> A test car travels in a straight line along the x-axis. The graph in Fig. E2.11 shows the car€™s position x as a function of time. Find its instantaneous velocity at points A through G.Figure E2.11:  Transcribed Image Text: x (m) 40 30 20 B. 10 2 3 4 5 6 7 89 10 t (s)
Answer Preview: Identify Find the instantaneous velocity of a car using a graph of its position as a f…

, Chapter: 4 -Problem: 26 >> True or false? You exert a push P on an object and it pushes back on you with a force F. If the object is moving at constant velocity, then F is equal to P, but if the object is being accelerated, then P must be greater than F.
Answer Preview: False Newtons third law requires tha…

, Chapter: 15 -Problem: 6 >> The speed of ocean waves depends on the depth of the water; the deeper the water, the faster the wave travels. Use this to explain why ocean waves crest and “break” as they near the shore.
Answer Preview: The waves slow down …

, Chapter: 19 -Problem: 26 >> Five moles of monatomic ideal gas have initial pressure 2.50 × 103 Pa and initial volume 2.10 m3. While undergoing an adiabatic expansion, the gas does 1480 J of work. What is the final pressure of the gas after the expansion?
Answer Preview: IDENTIFY For an adiabatic process of an ideal gas p 1 V 1 p 2 V 2 no heat enters or leaves the gas T…

, Chapter: 12 -Problem: 11 >> The purity of gold can be tested by weighing it in air and in water. How? Do you think you could get away with making a fake gold brick by gold plating some cheaper material?
Answer Preview: The weight in air is w air mg obj V obj g where obj and V obj are the density and volume of the obje…

, Chapter: 29 -Problem: 8 >> Consider the situation in Exercise 29.21. In part (a), find the direction of the force that the large circuit exerts on the small one. Explain how this result is consistent with Lenz€™s law. Data from exercise 29.21A small, circular ring is inside a larger loop that is connected to a battery and a switch (Fig. E29.21). Use Lenz€™s law to find the direction of the current induced in the small ring.
Answer Preview: Just after the switch is closed the current increases from zero to …

, Chapter: 36 -Problem: 2 >> What is the difference between Fresnel and Fraunhofer diffraction? Are they different physical processes? Explain.
Answer Preview: Fresnel and Fraunhofer diffraction are ba…

, Chapter: 3 -Problem: 20 >> The position of a squirrel running in a park is given by r = [(0.280 m/s)t + (0.0360 m/s2)t2]i? + (0.0190 m/s3)t3 j?.(a) What are and ux(t) and uy(t), the x- and y-components of the velocity of the squirrel, as functions of time?(b) At t = 5.00 s, how far is the squirrel from its initial position?(c) At t = 5.00 s, what are the magnitude and direction of the squirrel’s velocity?
Answer Preview: Identify Given the position vector of a squirrel find …

, Chapter: 3 -Problem: 8 >> If a jumping frog can give itself the same initial speed regardless of the direction in which it jumps (forward or straight up), how is the maximum vertical height to which it can jump related to its maximum horizontal range Rmax = v20/g?
Answer Preview: R max v 0 g If the fro…

, Chapter: 16 -Problem: 23 >> Does an aircraft make a sonic boom only at the instant its speed exceeds Mach 1? Explain.
Answer Preview: No the aircraft continually produces a s…

, Chapter: 17 -Problem: 108 >> A metal sphere with radius 3.20 cm is suspended in a large metal box with interior walls that are maintained at 30.0°C. A small electric heater is embedded in the sphere. Heat energy must be supplied to the sphere at the rate of 0.660 J/s to maintain the sphere at a constant temperature of 41.0°C.(a) What is the emissivity of the metal sphere?(b) What power input to the sphere is required to maint
Answer Preview: IDENTIFY We have blackbody radiation The sphere at 41 0C 314 K radiates into the box but the bo…

, Chapter: 13 -Problem: 20 >> Many people believe that orbiting astronauts feel weightless because they are “beyond the pull of the earth’s gravity.” How far from the earth would a spacecraft have to travel to be truly beyond the earth’s gravitational influence? If a spacecraft were really unaffected by the earth’s gravity, would it remain in orbit? Explain. What is the real reason astronauts in orbit feel weightless?
Answer Preview: Only at an infinite distance from the earth is its gravitational force z…

, Chapter: 28 -Problem: 12 >> Two very long, parallel wires carry equal currents in opposite directions.(a) Is there any place that their magnetic fields completely cancel? If so, where? If not, why not?(b) How would the answer to part (a) change if the currents were in the same direction?
Answer Preview: a No Between the two wires the fields of the wires are in th…

, Chapter: 34 -Problem: 7 >> When a room has mirrors on two opposite walls, an infinite series of reflections can be seen. Discuss this phenomenon in terms of images. Why do the distant images appear fainter?
Answer Preview: Each image formed by one mirror serve…

, Chapter: 13 -Problem: 105 >> An object in the shape of a thin ring has radius a and mass M. A uniform sphere with mass m and radius R is placed with its center at a distance x to the right of the center of the ring, along a line through the center of the ring, and perpendicular to its plane (see Fig. E13.33). What is the gravitational force that the sphere exerts on the ring-shaped object? Show that your result reduces to the
Answer Preview: Identify The direct calculation of the force that the sphere exerts on the rin…

, Chapter: 4 -Problem: 50 >> You have landed on an unknown planet, Newtonia, and want to know what objects weigh there. When you push a

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