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physics
college physics a strategic approach 2nd
College Physics A Strategic Approach 2nd Edition Randall D. Knight, Brian Jones, Stuart Field - Solutions
An inexpensive microscope has a tube length of 12.0 cm, and its objective lens is labeled with a magnification of 10x.a. Calculate the focal length of the objective lens. b. What focal length eyepiece lens should the microscope have to give an overall magnification of 150X?
A nearsighted person has a near point of 20 cm and a far point of 40 cm. When he is wearing glasses to correct his distant vision, what is his near point? A. 10 cm B. 20 cm C. 40 cm D. 1.0 m
A standard biological microscope is required to have a magnification of 200x. a. When paired with a 10X eyepiece, what power objective is needed to get this magnification? b. What is the focal length of the objective?
The distance between the objective and eyepiece lenses in a microscope is 20 cm. The objective lens has a focal length of 5.0 mm. What eyepiece focal length will give the microscope an overall angular magnification of 350?
For the combination of two identical lenses shown in Figure P19.24, find the position, size, and orientation of the final image of the 2.0-cm-tall object. FIGURE P19.24 2.0 cm 14 36 cm f = 9.0 cm 15 cm
In a darkened room, red light shines on a red cup, a white card, and a blue toy. The cup, card, and toy will appear, respectively, A. Red, red, blue. B. Red, white, blue. C. Red, red, black. D. Red, black, blue.
For the combination of two lenses shown in Figure P19.25, find the position, size, and orientation of the final image of the 1.0-cm-tall object. FIGURE P19.25 f = 5.0 cm 1.0 cm 14 4.0 cm f= -8.0 cm 12 cm
An amateur astronomer looks at the moon through a tele- scope with a 15-cm-diameter objective. What is the minimum separation between two objects on the moon that she can resolve with this telescope? Assume her eye is most sensitive to light with a wavelength of 550 nm. A. 120 m B. 1.7 km C. 26
A researcher is trying to shoot a tranquilizer dart at a 2.0-m- tall rhino that is 150 m away. Its angular size as seen through the rifle telescope is 9.1°. What is the magnification of the telescope?
A ray of white light strikes the surface of a 4.0-cm- thick slab of flint glass as shown in Figure P19.31. As the ray enters the glass, it is dispersed into its constituent colors. Estimate how far apart the rays of deepest red and deepest violet light are as they ex it the bottom surface. Which
The objective lens of the refracting telescope at the Lick Observatory in California has a focal length of 57 ft. a. What is the refractive power of this lens? b. What focal length (mm) eyepiece would give a magnification of 1000x for this telescope?
A narrow beam of light with wavelengths from 450 nm to 700 nm is incident perpendicular to one face of a 40.00° prism made of crown glass, for which the index of refraction ranges from n = 1.533 to n = 1.517 for those wavelengths. What is the angular spread of the beam after passing through the
Jason uses a lens with focal length of 10.0 cm as a magnifier by holding it right up to his eye. He is observing an object that is 8.0 cm from the lens. What is the angular magnification of the lens used this way if Jason's near-point distance is 25 cm?
A magnifier is labeled "5X." What would its magnification be if used by a person with a near-point distance of 50 cm?
A 20 x microscope objective is designed for use in a microscope with a 16 cm tube length. The objective is marked NA = 0.40. What is the diameter of the objective lens?
A lens with a focal length of 25 cm is placed 40 cm in front of a lens with a focal length of 5.0 cm. How far from the second lens is the final image of an object infinitely far from the first lens? Is this image in front of or behind the second lens?
A microscope with a 5x objective lens images a 1.0-mm- diameter specimen. What is the diameter of the real image of this specimen formed by the objective lens?
Your task in physics lab is to make a microscope from two lenses. One lens has a focal length of 10 cm, the other a focal length of 3.0 cm. You plan to use the more powerful lens as the objective, and you want its image to be 16 cm from the lens, as in a standard biological microscope. a. How far
A 20X objective and 10x eyepiece give an angular magnification of 200x when used in a microscope with a 160 mm tube length. What magnification would this objective and eyepiece give if used in a microscope with a 200 mm tube length?
The objective lens and the eyepiece lens of a telescope are 1.0 m apart. The telescope has an angular magnification of 50. Find the focal lengths of the eyepiece and the objective.
Your telescope has an objective lens with a focal length of 1.0 m. You point the telescope at the moon, only to realize that the eyepiece is missing. Even so, you can still see the real image of the moon formed by the objective lens if you place your eye a little past the image so as to view the
Two stars have an angular separation of 3.3 X 10-6 rad. What diameter telescope objective is necessary to just resolve these two stars, using light with a wavelength of 650 nm?
The planet Neptune is 4.5 x 1012 m from the earth. Its diameter is 4.9 × 107 m. What diameter telescope objective would be necessary to just barely see Neptune as a disk rather than as a point of light? Assume a wavelength of 550 nm.
What is the angular resolution of the Hubble Space Telescope's 2.4-m-diameter mirror when viewing light with a wave- length of 550 nm? The resolution of a reflecting telescope is calculated exactly the same as for a refracting telescope.
The normal human eye has maximum visual acuity with a pupil size of about 3 mm. For larger pupils, acuity decreases due to increasing aberrations; for smaller pupils, acuity decreases due to increasing effects of diffraction. If your pupil diameter is 2.0 mm, as it would be in fairly bright light,
Microtubules are filamentous structures in cells that maintain cell shape and facilitate the movement of molecules within the cell.
A glass rod is charged to +5.0 nC by rubbing. a. Have electrons been removed from the rod or protons added? Explain. b. How many electrons have been removed or protons added?
What is alike about charges when we say "two like charges"? Do they look, smell, or taste the same?
A plastic rod is charged to -20 nC by rubbing. a. Have electrons been added to the rod or protons removed? Explain. b. How many electrons have been added or protons removed?
Suppose you have 1.0 mol of O2 gas. How many coulombs of positive charge are contained in the atomic nuclei of this gas?
When you take clothes out of the drier right after it stops, the clothes often stick to your hands and arms. Is your body charged? If so, how did it acquire a charge? If not, why does this happen?
Figure Q20.8 shows a positively charged rod held near, but not touching, a neutral metal sphere. a. Add plusses and minuses to the figure to show the charge distribution on the sphere. b. Does the sphere experience a net force? If so, in which direction? Explain. XXXXX Metal FIGURE Q20.8
Two identical metal spheres A and B are connected by a metal rod. Both are initially neutral 1.0 × 1012 electrons are added to sphere A, then the connecting rod is removed. After- ward, what are the charge of A and the charge of B?
Two identical metal spheres A and B are connected by a plastic rod. Both are initially neutral. 1.0 × 1012 electrons are added to sphere A, then the connecting rod is removed. Afterward, what are the charge of A and the charge of B?
You are given two metal spheres on portable insulating stands, a glass rod, and a piece of silk. Explain how to give the spheres exactly equal but opposite charges.
A small plastic sphere with a charge of -5.0 nC is near another small plastic sphere with a charge of -12 nC. If the spheres repel one another with a force of magnitude 8.2 x 10-4 N, what is the distance between the spheres?
A honeybee acquires a positive electric charge as it flies. through the air. This charge causes pollen grains to be attracted to the bee. Explain, using words and diagrams, how a neutral, conducting pollen grain will be attracted to a positively charged bee.
A metal rod A and a metal sphere B, on insulating stands, touch each other as shown in Figure Q20.12. They are origi- nally neutral. A positively charged rod is brought near (but not touching) the far end of A. While the charged rod is still close, A and B are separated. The charged rod is then
In Figure P20.15, charge q2 experiences no net electric force. What is q1? FIGURE P20.15 91 10 cm -2.0 nC 10 cm 92
A small metal bead, labeled A, has a charge of 25 nC. It is touched to metal bead B, initially neutral, so that the two beads share the 25 nC charge, but not necessarily equally. When the two beads are then placed 5.0 cm apart, the force between them is 5.4 X 10-4 N. What are the charges A and B on
Object A, which has been charged to +10 nC, is at the origin. Object B, which has been charged to -20 nC, is at (x, y) = (0.0 cm, 2.0 cm). What are the magnitude and direction of the electric force on each object?
When DNA breaks into fragments in a cell, electrostatic forces may actually inhibit repair. Explain why this happens.
What are the strength and direction of the electric field 2.0 cm from a small glass bead that has been charged to +6.0 nC?
A 30 nC charged particle and a 50 nC charged particle are near each other. There are no other charges nearby. The electric force on the 30 nC particle is 0.035 N. The 50 nC particle is then moved very far away. Afterward, what is the magnitude of the electric field at its original position?
A-10 nC charge is located at the origin. a. What are the strengths of the electric fields at the positions (x, y) = (0.0 cm, 5.0 cm), (-5.0 cm, -5.0 cm), and (-5.0 cm, 5.0 cm)? b. Draw a field diagram showing the electric field vectors at these points.
Two lightweight, electrically neutral conducting balls hang from threads. Choose the diagram in Figure Q20.23 that shows how the balls hang after:a. Both are touched by a negatively charged rod. b. Ball 1 is touched by a negatively charged rod and ball 2 is touched by a positively charged rod. c.
All the charges in Figure Q20.26 have the same magnitude. In which case does the electric field at the dot have the largest magnitude? A. C. FIGURE Q20.26 B. D.
a. Is there a point between a 10 nC charge and a 20 nC charge at which the electric field is zero? If so, which charge is this point closer to? If not, why not? b. Repeat part a for the case of a 10 nC charge and a -20 nC charge.
A rod has positive charge +q at one end and negative charge -q at the other, forming a dipole. The dipole is placed in a nonuniform electric field represented by the field lines in Figure Q20.30. Which arrow best indicates the direction of the net electric force on the dipole? +q FIGURE Q20.30 E.
Storm clouds may build up large negative charges near their bottom edges. The earth is a good conductor, so the charge on the cloud attracts an equal and opposite charge on the earth under the cloud. The electric field strength near the earth depends on the shape of the earth's surface, as we can
A glass bead charged to +3.5 nC exerts an 8.0 × 10-4 N repulsive electric force on a plastic bead 2.9 cm away. What is the charge on the plastic bead? A. +2.1 nC B. +7.4 nC C. +21 nCD. +740 nC
A neutral conducting sphere is between two parallel charged plates, as shown in Figure P20.33. Sketch the electric field lines in the region between the plates. Be sure to include the effect of the conducting sphere. H4+ - + FIGURE P20.33 +++
What is the magnitude of the force on the 1.0 nC charge in the middle of Figure P20.49 due to the four other charges? -2.0 nC 1.0 cm 1.0 nC -2.0 nC FIGURE P20.49 -2.0 nC 1.0 cm -2.0 nC
Two equally charged, 1.00 g spheres are placed with 2.00 cm between their centers. When released, each begins to accelerate at 225 m/s2. What is the magnitude of the charge on each sphere?
A 0.020 g plastic bead hangs from a lightweight thread. Another bead is fixed in position beneath the point where the thread is tied. If both beads have charge q, the moveable bead swings out to the position shown in Figure P20.62. What is q? 9 45° 5.0 cm FIGURE P20.62 9
A 5.0 nC point charge sits at x = 0. At the same time, a 4500 N/C uniform electric field (created by distant source charges) points in the positive x-direction. At what point along the x-axis, if any, would.(a) A proton (b) An electron experience no net force?
The electron gun in a television tube uses a uniform electric field to accelerate electrons from rest to 5.0 x 107 m/s in a distance of 1.2 cm. What is the electric field strength?
A bead with a mass of 0.050 g and a charge of 15 nC is free to slide on a vertical rod. At the base of the rod is a fixed 10 nC charge. In equilibrium, at what height above the fixed charge does the bead rest?
A small bead with a positive charge q is free to slide on a horizontal wire of length 4.0 cm. At the left end of the wire is a fixed charge q, and at the right end is a fixed charge 4q. How far from the left end of the wire does the bead come to rest?
An "energy bar" contains 6.0 g of fat. How much energy is this in joules? In calories? In Calories?
An "energy bar" contains 22 g of carbohydrates. How much energy is this in joules? In calories? In Calories?
An "energy bar" contains 22 g of carbohydrates. If the energy bar was his only fuel, how far could a 68 kg person walk at 5.0 km/h?
Suppose your body was able to use the chemical energy in gasoline. How far could you pedal a bicycle at 15 km/h on the energy in 1 gal of gas? (1 gal of gas has a mass of 3.2 kg.)
A typical photovoltaic cell delivers 4.0 X 10-3 W of electric energy when illuminated with 1.2 x 10-1 W of light energy. What is the efficiency of the cell?
An individual white LED (light-emitting diode) has an efficiency of 20% and uses 1.0 W of electric power. How many LEDs must be combined into one light source to give a total of 1.6 W of visible-light output (comparable to the light output of a 40 W incandescent bulb)? What total power is necessary
You're stranded on a remote desert island with only a chicken, a bag of corn, and a shade tree. To survive as long as possible in hopes of being rescued, should you eat the chicken at once and then the corn? Or eat the corn, feeding enough to the chicken to keep it alive, and then eat the chicken
A fast-food hamburger (with cheese and bacon) contains 1000 Calories. What is the burger's energy in joules?
For most automobiles, the number of miles per gallon decreases as highway speed increases. Fuel economy drops as speeds increase from 55 to 65 mph, then decreases further as speeds increase to 75 mph. Explain why this is the case.
In an average human, basic life processes require energy to be supplied at a steady rate of 100 W. What daily energy intake, in Calories, is required to maintain these basic processes?
When the space shuttle returns to earth, its surfaces get very hot as it passes through the atmosphere at high speed. a. Has the space shuttle been heated? If so, what was the source of the heat? If not, why is it hot? b. Energy must be conserved. What happens to the space shuttle's initial
A bottle of helium gas and a bottle of argon gas contain equal numbers of atoms at the same temperature. Which bottle, if either, has the greater total thermal energy?
The label on a candy bar says 400 Calories. Assuming a typical efficiency for energy use by the body, if a 60 kg person were to use the energy in this candy bar to climb stairs, how high could she go?
A weightlifter curls a 30 kg bar, raising it each time a distance of 0.60 m. How many times must he repeat this exercise to burn off the energy in one slice of pizza?
A weightlifter works out at the gym each day. Part of her routine is to lie on her back and lift a 40 kg barbell straight up from chest height to full arm extension, a distance of 0.50 m. a. How much work does the weightlifter do to lift the barbell one time? b. If the weightlifter does 20
The planet Mercury's surface temperature varies from 700 K during the day to 90 K at night. What are these values in °C and °F?
An ideal gas is at 20°C. If we double the average kinetic energy of the gas atoms, what is the new temperature in °C?
An ideal gas is at 20°C. The gas is cooled, reducing the thermal energy by 10%. What is the new temperature in °C?
An ideal gas at °C consists of 1.0 X 1023 atoms. 10 J of thermal energy are added to the gas. What is the new temperature in °C?
An ideal gas at 20°C consists of 2.2 x 1022 atoms. 4.3 J of thermal energy are removed from the gas. What is the new temperature in °C?
In a gasoline engine, fuel vapors are ignited by a spark. In a diesel engine, a fuel-air mixture is drawn in, then rapidly com- pressed to as little as 1/20 the original volume, in the process increasing the temperature enough to ignite the fuel-air mixture. Explain why the temperature rises during
600 J of heat energy are transferred to a system that does 400 J of work. By how much does the system's thermal energy change?
1300 J of energy are transferred to a system in the form of heat while the thermal energy increases by 150 J. How much work is done on or by the system?
10 J of heat are removed from a gas sample while it is being compressed by a piston that does 20 J of work. What is the change in the thermal energy of the gas? Does the temperature of the gas increase or decrease?
A container holding argon atoms changes temperature by 20°C when 30 J of heat are removed. How many atoms are in the container?
A heat engine with a high-temperature reservoir at 400 K has an efficiency of 0.20. What is the maximum possible temperature of the cold reservoir?
An engine does 10 J of work and exhausts 15 J of waste heat. a. What is the engine's efficiency? b. If the cold-reservoir temperature is 20°C, what is the mini- mum possible temperature in C of the hot reservoir?
An engine operating at maximum theoretical efficiency whose cold-reservoir temperature is 7°C is 40% efficient. By how much should the temperature of the hot reservoir be increased to raise the efficiency to 60%?
Some heat engines can run on very small temperature differences. One manufacturer claims to have a very small heat engine that can run on the temperature difference between your hand and the air in the room. Estimate the theoretical maximum efficiency of this heat engine.
An engineer claims to have measured the characteristics of a heat engine that takes in 100 J of thermal energy and produces 50 J of useful work. Is this engine possible? If so, what is the smallest possible ratio of the temperatures (in kelvin) of the hot and cold reservoirs?
Each second, a nuclear power plant generates 2000 MJ of thermal energy from nuclear reactions in the reactor's core. This energy is used to boil water and produce high-pressure steam at 300°C. The steam spins a turbine, which produces 700 MJ of electric power, then the steam is condensed and the
250 students sit in an auditorium listening to a physics lecture. Because they are thinking hard, each is using 125 W of metabolic power, slightly more than they would use at rest. An air conditioner with a COP of 5.0 is being used to keep the room at a constant temperature. What minimum electric
Driving on asphalt roads entails very little rolling resistance, so most of the energy of the engine goes to overcoming air resistance. But driving slowly in dry sand is another story. If a 1500 kg car is driven in sand at 5.0 m/s, the coefficient of rolling friction is 0.06. In this case, nearly
Air conditioners sold in the United States are given a sea- sonal energy-efficiency ratio (SEER) rating that consumers can use to compare different models. A SEER rating is the ratio of heat pumped to energy input, similar to a COP but using English units, so a higher SEER rating means a more
The surface waters of tropical oceans are at a temperature of 27°C while water at a depth of 1200 m is at 3°C. It has been suggested these warm and cold waters could be the energy reservoirs for a heat engine, allowing us to do work or generate electricity from the thermal energy of the ocean.
The light energy that falls on a square meter of ground over the course of a typical sunny day is about 20 MJ. The average rate of electric energy consumption in one house is 1.0 kW. a. On average, how much energy does one house use during each 24 h day? b. If light energy to electric energy
Which contains the most moles: 10 g of hydrogen gas, 100 g of carbon, or 50 g of lead?
Which has more mass, a mole of Ne gas or a mole of N2gas?
How many grams of water (H2O) have the same number of oxygen atoms as 1.0 mol of oxygen gas?
If you launch a projectile upward with a high enough speed, its kinetic energy is sufficient to allow it to escape the earth's gravity-it will go up and not come back down. Given enough time, hydrogen and helium gas atoms in the earth's atmosphere will escape, so these elements are not present in
How many atoms of hydrogen are in 100 g of hydrogen peroxide (H2O2)?
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