Question: An instrument known as an atomic force

> A parallel plate capacitor has a capacitance of 2.0 µF and plate separation of 1.0 mm. (a) How much potential difference can be placed across the capacitor before dielectric breakdown of air occurs (Emax = 3 × 106 V/m)? (b) What is the magnitude of the

> Points A and B are at the same potential. What is the total work that must be done by an external agent to move a charge from A to B? Does your answer mean that no external force need be applied? Explain.

> A charged particle is accelerated from rest through a potential difference ΔV. The particle then passes straight through a velocity selector (field magnitudes E and B). Derive an expression for the charge-to-mass ratio (q/m) of the particle in terms of Δ

> What are some of the advantages of using mirrors rather than lenses for astronomical telescopes?

> 11. A woman stands on a bathroom scale in an elevator that is not moving. The scale reads 500 N. The elevator then moves downward at a constant velocity of 4.5 m/s. What does the scale read while the elevator descends with constant velocity? (a) 100 N (b

> In a reciprocating saw, a Scotch yoke converts the rotation of the motor into the back-and-forth motion of the blade. The Scotch yoke is a mechanical device used to convert oscillatory motion to circular motion or vice versa. A wheel with a fixed knob ro

> The motion of a simple pendulum is approximately SHM only if the amplitude is small. Consider a simple pendulum that is released from a horizontal position (θi = 90° in Fig. 10.23). (a) Using conservation of energy, find the speed of the pendulum bob at

> The f-stop of a camera lens is defined as the ratio of the focal length of lens to the diameter of the aperture. A large f-stop therefore means a small aperture. If diffraction is the only consideration, would you use the largest or the smallest f-stop t

> An object is subjected to two constant forces that are perpendicular to each other. Can a set of x- and y-axes be chosen so that the acceleration of the object has only one nonzero component? If so, how? Explain.

> Suppose some astronauts have landed on Mars. When the astronauts ask a question of mission control personnel on Earth, what is the shortest possible time they have to wait for a response? The average distance from Mars to the Sun is 2.28 × 1011 m.

> Two sheets of ideal polarizing material are placed with their transmission axes at right angles to each other. A third polarizing sheet is placed between them with its transmission axis at 45° to the axes of the other two. (a) If unpolarized light of in

> Four long straight wires, each with current I, overlap to form a square with side 2r. (a) Find the magnetic field at the center of the square. (b) Compare your answer with the magnetic field at the center of a circular loop of radius r carrying current

> A 1500 kg car moving east at 17 m/s collides with a 1800 kg car moving south at 15 m/s, and the two cars stick together. (a) What is the velocity of the cars right after the collision? (b) How much kinetic energy was converted to another form during th

> If a capacitor has a capacitance of 10.2 µF and we wish to lower the potential difference across the plates by 60.0 V, what magnitude of charge will we have to remove from each plate?

> In aviation, a standard rate turn proceeds at an angular speed of 180° per minute. What is the radius of a standard rate turn for a plane moving at 240 m/s?

> Roger is in a ship offshore and listening to a baseball game on his radio. He notices that there is destructive interference when seaplanes from the nearby Coast Guard station are flying directly overhead at elevations of 780 m, 975 m, and 1170 m. The br

> (a) If you measure the ship that passes you in Problem 76 to be 24 m long, how long will the observers on Earth measure that ship to be? (b) If there is a rod on your spaceship that you measure to be 24 m long, how long will the observers on Earth measu

> A portable radio requires an emf of 4.5 V. Olivia has only two nonrechargeable 1.5 V batteries, but she finds a larger 6.0 V battery. (a) How can she arrange the batteries to produce an emf of 4.5 V? Draw a circuit diagram. (b) Is it advisable to use th

> Zach insists that the seasons are caused by the elliptical shape of Earth’s orbit. He says that it is summer when Earth is closest to the Sun and winter when it is farthest away from the Sun. What evidence can you think of to show that the seasons are no

> In musical acoustics, a frequency ratio of 2:1 is called an octave. Humans with extremely good hearing can hear sounds ranging from 20 Hz to 20 kHz, which is approximately 10 octaves (since 210 = 1024 ≈ 1000). (a) Approximately how many octaves of visib

> (a) In double-slit interference, how does the slit separation affect the distance between adjacent interference maxima? (b) How does the distance between the slits and screen affect that separation? (c) If you are trying to resolve two closely spaced m

> The International Space Station (ISS) has a mass of 4.5 × 105 kg and orbits Earth at a speed of 7.7 km/s. By what percentage does the approximate momentum of the ISS calculated nonrelativistically differ from the relativistic momentum? [Hint: Use one of

> A positive charge is initially at rest in an electric field and is free to move. Does the charge start to move toward a position of higher or lower potential? What happens to a negative charge in the same situation?

> Light visible to humans consists of electromagnetic waves with wavelengths (in air) in the range 400–700 nm (4.0 × 10−7 m to 7.0 × 10−7 m). The speed of light in air is 3.0 × 108 m/s. What are the frequencies of electromagnetic waves that are visible?

> Using the results of Problem 75, we can find the electric field at any radius for any spherically symmetrical charge distribution. A solid sphere of charge of radius R has a total charge of q uniformly spread throughout the sphere. (a) Find the magnitud

> What is the potential energy if a third point charge q = −4.2 nC is placed at point b?

> 1. Which one of these statements is true? (a) The principal quantum number of the electron in a hydrogen atom does not affect its energy. (b) The principal quantum number of an electron in its ground state is zero. (c) The orbital angular momentum quantu

> A curve in a stretch of highway has radius 512 m. The road is unbanked. The coefficient of static friction between the tires and road is 0.70. (a) What is the maximum speed that a car can travel around the curve without skidding? (b) Explain what happe

> A beam of neutrons has the same de Broglie wavelength as a beam of photons. Is it possible that the energy of each photon is equal to the kinetic energy of each neutron? If so, at what de Broglie wavelength(s) does this occur? [Hint: For the neutron, use

> Glenda drops a coin from ear level down a wishing well. The coin falls a distance of 7.00 m before it strikes the water. If the speed of sound is 343 m/s, how long after Glenda releases the coin will she hear a splash?

> Find the molar mass of ammonia (NH3).

> A thin film of oil with index of refraction of 1.50 sits on top of a pool of water with index of refraction of 1.33. When light is incident on this film, a maximum is observed in reflected light at 480 nm and a minimum is observed in reflected light at 6

> If rays from points on an object are converging as they enter a lens, is the object real or virtual?

> Why must projectors and cameras form real images? Does the lens in the eye form real or virtual images on the retina?

> The windings of an electromagnet have inductance L = 8.0 H and resistance R = 2.0 Ω. A 100.0 V dc power supply is connected to the windings by closing switch S2. (a) A few minutes later, what is the current in the windings? (b) The electrom

> A car drives around a curve with radius 410 m at a speed of 32 m/s. The road is banked at 5.0°. The mass of the car is 1400 kg. (a) What is the frictional force on the car? (b) At what speed could you drive around this curve so that the force of fricti

> What causes chromatic aberration? What can be done to compensate for chromatic aberration?

> A star is moving away from Earth at a speed of 2.4 × 108 m/s. Light of wavelength 480 nm is emitted by the star. What is the wavelength as measured by an Earth observer?

> For an ideal inductor in an ac circuit, explain why the voltage across the inductor must be zero when the current is maximum.

> A hot air balloon is floating in equilibrium with the surrounding air. (a) How does the pressure inside the balloon compare with the pressure outside? (b) How does the density of the air inside compare to the density outside?

> A parallel plate capacitor has a capacitance of 1.20 nF. There is a charge of 0.80 µC on each plate. How much work must be done by an external agent to double the plate separation while keeping the charge constant?

> The graph shows x(t) for an object traveling along the x-axis. Plot vx as a function of time for this object from t = 0 to t = 8 s.

> A man requires reading glasses with +2.0 D refractive power to read a book held 40.0 cm away with a relaxed eye. Assume the glasses are 2.0 cm from his eyes. (a) What is his uncorrected far point? (b) What refractive power lenses should he use for dist

> A solid copper disk of radius R rotates at angular velocity ω in a perpendicular magnetic field B. The figure shows the disk rotating clockwise and the magnetic field into the page. (a) Is the charge that accumulates on the edge of the disk p

> An African swallow carrying a very small coconut is flying horizontally with a speed of 18 m/s. (a) If it drops the coconut from a height of 10 m above Earth, how long will it take before the coconut strikes the ground? (b) At what horizontal distance

> A bird is perched on a high-voltage power line whose potential varies between −100 kV and +100 kV. Why is the bird not electrocuted?

> A charged parallel plate capacitor has the space between the plates filled with air. The capacitor has been disconnected from the battery that charged it. Describe quantitatively what happens to the capacitance, the potential difference, the charge on th

> In some textbooks, the electric field is called the flux density. Explain the meaning of this term. Does flux density mean the flux per unit volume? If not, then what does it mean?

> A parallel plate capacitor has the space between the plates filled with a slab of dielectric with κ = 3. While the capacitor is connected to a battery, the dielectric slab is removed. Describe quantitatively what happens to the capacitance, the potential

> At a grocery store, a spring scale (spring constant = 450 N/m) hangs near the produce section. The spring hangs vertically with a 0.250 kg pan suspended from its lower end. Jenna drops a 2.20 kg bag of oranges from a height of 30.0 cm above the pan. The

> The particle in a box model is often used to make rough estimates of ground-state energies. Suppose that you have a neutron confined to a one-dimensional box of length equal to a nuclear diameter (say 10−14 m). What is the ground-state energy of the conf

> In a transformer, two coils are wound around an iron core; an alternating current in one coil induces an emf in the second. The core is normally made of either laminated iron—thin sheets of iron with an insulating material between them—or a bundle of par

> Photons of wavelength 350 nm are incident on a metal plate in a photocell, and electrons are ejected. A stopping potential of 1.10 V is able to just prevent any of the ejected electrons from reaching the opposite electrode. What is the maximum wavelength

> How far does a beam of light travel in 1 ns?

> Dry air breaks down for an electric field of about 3000 V/mm. Is it possible to build a parallel plate capacitor with a plate spacing of 1 mm that can be charged to a potential difference greater than 3000 V? If so, explain how.

> The figure shows a schematic diagram of a defective eye. What is this defect called?

> 1. A leopard starts from rest at t = 0 and runs in a straight line with a constant acceleration until t = 3.0 s. The distance covered by the leopard between t = 1.0 s and t = 2.0 s is (a) the same as the distance covered during the first second. (b) twic

> A neutron, with rest energy 939.6 MeV, has momentum 935 MeV/c downward. What is its total energy?

> Two long, straight wires, each with a current of 12.0 A, are placed on two corners of an equilateral triangle with sides of length 2.50 cm as shown. Both of the wires have a current into the page. (a) What is the magnetic field at the third corner of th

> You are asked to hang a uniform beam and sign using a cable that has a breaking strength of 417 N. The store owner desires that it hang out over the sidewalk as shown. The sign has a weight of 200.0 N and the beam's weight is 50.0 N. The beam's length is

> A beam of electrons traveling with a speed of 3.0 × 107 m/s enters a uniform, downward electric field of magnitude 2.0 × 104 N/C between the deflection plates of an oscilloscovpe. The initial velocity of the electrons is perpend

> A stone is launched straight up by a slingshot. Its initial speed is 19.6 m/s, and the stone is 1.50 m above the ground when launched. (a) How high above the ground does the stone rise? (b) How much time elapses before the stone hits the ground?

> Humans can hear sounds with frequencies up to about 20.0 kHz, but dogs can hear frequencies up to about 40.0 kHz. Dog whistles are made to emit sounds that dogs can hear but humans cannot. If the part of a dog whistle that actually produces the high freq

> The electric field just above Earth's surface on a clear day in an open field is about 150 V/m downward. Which is at a higher potential: Earth or the upper atmosphere?

> In Fig. 17.13, why is the person touching the dome of the van de Graaff generator not electrocuted even though there may be a potential difference of hundreds of thousands of volts between him and the ground?

> Under favorable conditions, the human eye can detect light waves with intensities as low as 2.5 × 10−12 W/m2. (a) At this intensity, what is the average power incident on a pupil of diameter 9.0 mm? (b) If this light is produced by an isotropic source 1

> At what time is energy stored in the inductor 0.10 times its initial value?

> Another example of motional emf is a rod attached at one end and rotating in a plane perpendicular to a uniform magnetic field. We can analyze this motional emf using Faraday’s law. (a) Consider the area that the rod sweeps out in each

> A uniform string of length 10.0 m and weight 0.25 N is attached to the ceiling. A weight of 1.00 kN hangs from its lower end. The lower end of the string is suddenly displaced horizontally. How long does it take the resulting wave pulse to travel to the

> If we know the potential at a single point, what (if anything) can we say about the magnitude of the electric field at that same point?

> It takes a flea 1.0 × 10−3 s to reach a peak speed of 0.74 m/s. (a) If the mass of the flea is 0.45 × 10−6 kg, what is the average power required? (b) Insect muscle has a maximum output of 60 W/kg. If 20% of the flea’s weight is muscle, can the muscle

> A lens is placed at the end of a bundle of optical fibers in an endoscope. The purpose of the lens is to make the light rays parallel before they enter the fibers (in other words, to put the image at infinity). What is the advantage of using a lens with

> A 6.2 cm by 2.2 cm parallel plate capacitor has the plates separated by a distance of 2.0 mm. (a) When 4.0 × 10−11 C of charge is placed on this capacitor, what is the electric field between the plates? (b) If a dielectric with dielectric constant of 5

> An axon has the outer part of its membrane positively charged and the inner part negatively charged. The membrane has a thickness of 4.4 nm and a dielectric constant κ = 5. If we model the axon as a parallel plate capacitor whose area is 5 µm2, what is i

> Show that the amplitudes of the graphs you made in Problem 89 satisfy the equation A′ = 2A cos (ωt), where A′ is the amplitude of the wave you plotted and A is 5.0 cm, the amplitude of the waves that were added together.

> A converging lens made from dense flint glass is placed into a container of transparent glycerin. Describe what happens to the focal length.

> Why must a blood pressure cuff be wrapped around the arm at the same vertical level as the heart?

> An electron is placed in a uniform electric field of strength 232 N/C. If the electron is at rest at the origin of a coordinate system at t = 0 and the electric field is in the positive x-direction, what are the x- and y-coordinates of the electron at t

> During a thunderstorm, some cows gather under a large tree. One cow stands facing directly toward the tree. Another cow stands at about the same distance from the tree, but it faces sideways (tangent to a circle centered on the tree). Which cow do you th

> The ball is released from rest when the thread makes an angle of 32° with the vertical. How fast is it moving when the thread is vertical?

> Calculate the kinetic energy of the alpha particle in Problem 25. This time, do not assume that the / nucleus is at rest after the reaction. Start by figuring out the ratio of the kinetic energies of the alpha particle and the / nucleus.

> A photoelectric experiment illuminates the same metal with six different ultraviolet sources. Both the wavelength and the intensity vary from one source to another. Rank the six situations in order of the stopping potential, largest to smallest. (a) λ =

> A curve in a stretch of highway has radius 610 m. The road is banked at angle 5.8° to the horizontal. The coefficient of static friction between the tires and road is 0.50. What is the fastest speed that a car can travel through the curve without skiddin

> The voltage across an inductor and the current through the inductor are related by vL = L Δi/Δt. Suppose that i(t) = I sin ωt. (a) Sketch a graph of i(t), showing at least one full cycle. (b) Using a small-angle approximation (Appendix A.9), find the s

> Suppose that an ideal capacitor and an ideal inductor are connected in series in an ac circuit. (a) What is the phase difference between vC(t) and vL(t)? [Hint: Since they are in series, the same current i(t) flows through both.] (b) If the rms voltage

> If an object is traveling at a constant velocity, is it necessarily traveling in a straight line? Explain.

> Repeat Problem 22, but now the copper washer and the steel bolt are both raised to the same temperature. At what temperature will the washer fit on the bolt?

> What are some of the advantages of a UV microscope over a visible light microscope? What are some of the disadvantages?

> An old highway is built out of concrete blocks of equal length. A car traveling on this highway feels a little bump at the joint between blocks. The passengers in the car feel that the ride is uncomfortable at a speed of 45 mi/h, but much smoother at spe

> Your friend balances a package with mass m = 10 kg on top of his head while standing. The mass of his upper body is M = 55 kg (about 65% of his total mass). Because the spine is vertical rather than horizontal, the force exerted by the sacrum on the spin

> A solenoid with 8500 turns per meter has radius 65 cm. The current in the solenoid is 25.0 A. A circular loop of wire with 100 turns and radius 8.00 cm is put inside the solenoid. The current in the circular loop is 2.20 A. What is the maximum possible m

> If a piece of white cardboard is placed at the location of a virtual object, what (if anything) would be seen on the cardboard?

> Estimate the minimum total kinetic energy of the 2H and 3H nuclei necessary to allow the fusion reaction of Eq. (29-49) to take place.

> A horizontal segment of pipe tapers from a cross-sectional area of 50.0 cm2 to 0.500 cm2. The pressure at the larger end of the pipe is 1.20 × 105 Pa, and the speed is 0.040 m/s. What is the pressure at the narrow end of the segment?

> The charge on a capacitor doubles. What happens to its capacitance?

> Four people sit in a car. The masses of the people are 45 kg, 52 kg, 67 kg, and 61 kg. The car’s mass is 1020 kg. When the car drives over a bump, its springs cause an oscillation with a frequency of 2.00 Hz. What would the frequency be if only the 45 kg

> You are hiking through a lush forest with some of your friends when you come to a large river that seems impossible to cross. However, one of your friends notices an old metal barrel sitting on the shore. The barrel is shaped like a cylinder and is 1.20

> You will be hiking to a lake with some of your friends by following the trails indicated on a map at the trail-head. The map says that you will travel 1.6 mi directly north, then 2.2 mi in a direction 35° east of north, then finally 1.1 mi in a direction

> A sphere of copper is subjected to 100 MPa of pressure. The copper has a bulk modulus of 130 GPa. By what fraction does the volume of the sphere change? By what fraction does the radius of the sphere change?

> A light wave passes through a hazy region in the sky. If the electric field vector of the emerging wave is one quarter that of the incident wave, what is the ratio of the transmitted intensity to the incident intensity?