Questions and Answers of College Physics A Strategic Approach 2nd

A capacitor with its plates separated by paper stores 4.4 nC of charge when it is connected to a particular battery. An otherwise identical capacitor, but with its plates separated by Pyrex glass, is
What is the electric potential energy of the electron in Figure P21.49? The protons are fixed and can't move. FIGURE P21.49 Protons 0.50 nm 0.50 nm 2.0 nm Electron
A pair of 10 μF capacitors in a high-power laser are charged to 1.7 kV.a. What charge is stored in each capacitor? b. How much energy is stored in each capacitor?
a. What is the electric potential at point A in Figure P21.59?b. What is the potential energy of a proton at point A? 10 nC 4.0 cm 2.0 cm 5.0 nC FIGURE P21.59 -5.0 nC A
Electric outlets have a voltage of approximately 120 V between the two parallel slots. Estimate the electric field strength between these two slots.
Estimate the magnitude of the electric field in a cell membrane with a thickness of 8 nm.
A Na+ ion moves from inside a cell, where the electric potential is -70 mV, to outside the cell, where the potential is 0 V. What is the change in the ion's electric potential energy as it moves from
In the early 1900s, Robert Millikan used small charged droplets of oil, suspended in an electric field, to make the first quantitative measurements of the electron's charge. A 0.70-um- diameter
A 2.5-mm-diameter sphere is charged to -4.5 nC. An electron fired directly at the sphere from far away comes to within 0.30 mm of the surface of the target before being reflected.a. What was the
The plates of a 3.0 nF parallel-plate capacitor are each 0.27 m2 in area. a. How far apart are the plates if there's air between them? b. If the plates are separated by a Teflon sheet, how thick is
The dielectric in a capacitor serves two purposes. It increases the capacitance, compared to an otherwise identical capacitor with an air gap, and it increases the maximum potential difference the
Two wires connect a lightbulb to a battery, completing a circuit and causing the bulb to glow. Do the simple observations and measurements that you can make on this circuit prove that something is
Two wires connect a lightbulb to a battery, completing a circuit and causing the bulb to glow. Are the simple observations and measurements you can make on this circuit able to distinguish a current
A wire carries a 1.0 A current for 30 s. How many electrons move past a point in the wire?
What causes electrons to move through a wire as a current?
When a nerve cell depolarizes, charge is transferred across the cell membrane, changing the potential difference. For a typical nerve cell, 9.0 pC of charge flows in a time of 0.50 ms. What is the
A lightbulb is connected to a battery by two copper wires of equal lengths but different thicknesses. A thick wire connects one side of the lightbulb to the positive terminal of the battery and a
A wire carries a 15 μA current. How many electrons pass a given point on the wire in 1.0 s?
In a typical lightning strike, 2.5 C flows from cloud to ground in 0.20 ms. What is the current during the strike?
A wire carries a 4 A current. What is the current in a second wire that delivers twice as much charge in half the time?
A capacitor is charged to 6.0 X 10-4 C, then discharged by connecting a wire between the two plates. 40 us after the dis- charge begins, the capacitor still holds 13% of its original charge. What was
Metal 1 and metal 2 are each formed into 1-mm-diameter wires. The electric field needed to cause a 1 A current in metal 1 is larger than the electric field needed to cause a 1 A current in metal 2.
Cells in the nervous system have a potential difference of 70 mV across the cell membrane separating the interior of the cell from the extracellular fluid. This potential difference is maintained by
If you change the temperature of a segment of metal wire, the dimensions change and the resistivity changes. How does each of these changes affect the resistance of the wire?
A battery supplies a steady 1.5 A current to a circuit. If the charges moving in the battery are positive ions with charge e, how many ions per second are transported from the negative terminal to
What is the emf of a battery that does 0.60 J of work to transfer 0.050 C of charge from the negative to the positive terminal?
An individual hydrogen-oxygen fuel cell has an output of 0.75 V. How many cells must be connected in series to drive a 24.0 V motor?
When lightning strikes the ground, it generates a large electric field along the surface of the ground directed toward the point of the strike. People near a lightning strike are often injured not by
An electric catfish can generate a significant potential difference using stacks of special cells called electrocytes. Each electrocyte develops a potential difference of 110 mV. How many cells must
Over time, atoms "boil off" the hot filament in an incandescent bulb and the filament becomes thinner. How does this affect the brightness of the lightbulb?
Lightbulbs are typically rated by their power dissipation when operated at a given voltage. Which of the following light- bulbs has the largest current through it when operated at the voltage for
We can model the rear window defroster in a car as a resistor that is connected to the car's 12 V battery. The defroster is made of a material whose resistance increases rapidly as the temperature
Lightbulbs are typically rated by their power dissipation when operated at a given voltage. Which of the following light- bulbs has the largest resistance when operated at the voltage for which it's
What is the resistance of a. A 1.0-m-long copper wire that is 0.50 mm in diameter? b. A 10-cm-long piece of iron with a 1.0 mm X 1.0 mm square cross section?
A stereo amplifier creates a 5.0 V potential difference across a speaker. To double the power output of the speaker, the amplifier's potential difference must be increased to A. 7.1 V B. 10 V C. 14
A motorcyclist is making an electric vest that, when connected to the motorcycle's 12 V battery, will warm her on cold rides. She is using 0.25-mm-diameter copper wire, and she wants a current of 4.0
If a 1.5 V battery stores 5.0 kJ of energy (a reasonable value for an inexpensive C cell), for how many minutes could it sustain a current of 1.2 A? A. 2.7 B. 6.9 C. 9.0 D. 46
A 3.0 V potential difference is applied between the ends of a 0.80-mm-diameter, 50-cm-long nichrome wire. What is the current in the wire?
Figure Q22.28 shows a side view of a wire of varying circular cross section. Rank in order the currents flowing in the three sections. ½ FIGURE Q22.28
A 1.0-mm-diameter, 20-cm-long copper wire carries a 3.0 A current. What is the potential difference between the ends of the wire?
Figure P22.31 is a current-versus-potential-difference graph for a cylinder. What is the cylinder's resistance? 1 (A) 24 0- 0 50 FIGURE P22.31 -AV (V) 100
A person gains weight by adding fat and therefore adding girth to his body and his limbs, with the amount of muscle remaining constant. How will this affect the electrical resistance of his limbs?A.
A small electric lap blanket contains a 40-foot-long wire wrapped back and forth inside. An 18 V supply creates a current in this wire, warming it and thus the blanket. What is the electric field
Two identical lightbulbs are connected in series to a single 9.0 V battery. a. Sketch the circuit. b. Sketch a graph showing the potential as a function of distance through the circuit, starting
You've brought your 1000 W (120 V) hair dryer on vacation to Europe, where the standard outlet voltages are 230 V. Assuming the hair dryer can operate safely at the higher voltage, can you actually
A 70 W electric blanket runs at 18 V. a. What is the resistance of the wire in the blanket? b. How much current does the wire carry?
A 60-cm-long heating wire is connected to a 120 V outlet. If the wire dissipates 45 W, what are(a) The current in(b) The resistance of the wire?
A 3.0 V battery powers a flashlight bulb that has a resistance of 6.0 Ω. How much charge moves through the battery in 10 min?
For a science experiment you need to electroplate a 100-nm-thick zinc coating onto both sides of a very thin, 2.0 cm x 2.0 cm copper sheet. You know that the charge carriers in the ionic solution are
The hot dog cooker described in the chapter heats hot dogs by connecting them to 120 V household electricity. A typical hot dog has a mass of 60 g and a resistance of 150 Ω N. How long will it take
A 40 W (120 V) lightbulb has a tungsten filament of thickness 0.040 mm. The filament's operating temperature is 1500°C.a. How long is the filament? b. What is the resistance of the filament at
When the starter motor on a car is engaged, there is a 300 A current in the wires between the battery and the motor. Suppose the wires are made of copper and have a total length of 1.0 m. What
A wire is 2.3 m long and has a diameter of 0.38 mm. When connected to a 1.2 V battery, there is a current of 0.61 A. What material is the wire likely made of?
You've made the finals of the Science Olympics! As one of your tasks, you're given 1.0 g of copper and asked to make a wire, using all the metal, with a resistance of 1.0 Ω. Copper has a density of
Not too long ago houses were protected from excessive cur- rents by fuses rather than circuit breakers. Sometimes a fuse blew out and a replacement wasn't at hand. Because a copper penny happens to
An immersion heater used to boil water for a single cup of tea plugs into a 120 V outlet and is rated at 300 W. a. What is the resistance of the heater? b. Suppose your super-size, super-insulated
Is it ever possible for one sound wave in air to overtake and pass another? Explain.
Which has the greater density, 1 g of mercury or 1000 g of water?
A 100 mL beaker holds 120 g of liquid. What is the liquid's density in SI units?
Containers A and B have equal volumes. Container A holds helium gas at 1.0 atm pressure and 20°C. Container B is completely filled with a liquid whose mass is 7600 times the mass of helium gas in
You are given an irregularly shaped chunk of material and asked to find its density. List the specific steps that you would follow to do so.
Air enclosed in a sphere has density p = 1.4 kg/m3. What will the density be if the radius of the sphere is halved, com- pressing the air within?
Object 1 has an irregular shape. Its density is 4000 kg/m3.a. Object 2 has the same shape and dimensions as object 1, but it is twice as massive. What is the density of object 2? b. Object 3 has the
When you get a blood transfusion the bag of blood is held above your body, but when you donate blood the collection bag is held below. Why is this?
To explore the bottom of a 10-m-deep lake, your friend Tom proposes to get a long garden hose, put one end on land and the other in his mouth for breathing underwater, and descend into the depths.
Ethyl alcohol has been added to 200 mL of water in a container that has a mass of 150 g when empty. The resulting container and liquid mixture has a mass of 512 g. What volume of alcohol was added to
Helium-filled weather balloons are spherical when they reach very high altitudes. However, they are only partially inflated with helium before they are released. Explain why this is done.
A 35-cm-tall, 5.0-cm-diameter cylindrical beaker is filled to its brim with water. What is the downward force of the water on the bottom of the beaker?
Water expands when heated. Suppose a beaker of water is heated from 10°C to 90°C. Does the pressure at the bottom of the beaker increase, decrease, or stay the same? Explain.
Rank in order, from largest to smallest, the densities of objects A, B, and C in Figure Q13.15. Explain. A B FIGURE Q13.15 C
What is the gas pressure inside the box shown in Figure P13.16? gas 16 cm -Mercury FIGURE P13.16 6.0 cm
Refer to Figure Q13.16. Now A, B, and C have the same density, but still have the masses given in the figure. Rank in order, from largest to smallest, the sizes of the buoyant forces on A, B, and C.
Two pipes have the same inner cross-section area. One has a circular cross section and the other has a rectangular cross section with its height one-tenth its width. Through which pipe, if either,
An oil layer floats on 85 cm of water in a tank. The absolute pressure at the bottom of the tank is 112.0 kPa. How thick is the oil?
The little Dutch boy saved Holland by sticking his finger in the leaking dike. If the water level was 2.5 m above his finger, estimate the force of the water on his finger.
A 6.0-cm-tall cylinder floats in water with its axis perpendicular to the surface. The length of the cylinder above water is 2.0 cm. What is the cylinder's mass density?
A flat slab of styrofoam, with a density of 32 kg/m3, floats on a lake. What minimum volume must the slab have so that a 40 kg boy can sit on the slab without it sinking?
A child's water pistol shoots water through a 1.0-mm-diameter hole. If the pistol is fired horizontally 70 cm above the ground, a squirt hits the ground 1.2 m away. What is the volume flow rate
The leaves of a tree lose water to the atmosphere via the process of transpiration. A particular tree loses water at the rate of 3 × 10-8 m3/s; this water is replenished by the upward flow of sap
Figure P13.62 shows a section of a long tube that narrows near its open end to a diameter of 1.0 mm. Water at 20°C flows out of the open end at 0.020 L/s. What is the gauge pressure at point P,
Water flows at 5.0 L/s through a horizontal pipe that narrows smoothly from 10 cm diameter to 5.0 cm diameter. A pressure gauge in the narrow section reads 50 kPa. What is the reading of a pressure
Suppose that in response to some stimulus a small blood vessel narrows to 90% its original diameter. If there is no change in the pressure across the vessel, what is the ratio of the new volume flow
Sustained exercise can increase the blood flow rate of the heart by a factor of 5 with only a modest increase in blood pressure. This is a large change in flow. Although several factors come into
A person's heart rate is given in beats per minute. Is this a period or a frequency?
Figure Q14.3 shows the position-versus-time graph of a particle in SHM. a. At what time or times is the particle moving to the right at maximum speed? b. At what time or times is the particle
In the aftermath of an intense earthquake, the earth as a whole "rings" with a period of 54 minutes. What is the frequency (in Hz) of this oscillation?
In taking your pulse, you count 75 heartbeats in 1 min. What are the period (in s) and frequency (in Hz) of your heart's oscillations?
Make a table with 3 columns and 8 rows. In row 1, label the columns θ (°),θ (rad), and sineθ. In the left column, starting in row 2, write 0, 2, 4, 6, 8, 10, and 12. a. Convert each of these
A heavy steel ball is hung from a cord to make a pendulum. The ball is pulled to the side so that the cord makes a 5° angle with the vertical. Holding the ball in place takes a force of 20 N. If the
What are the (a) amplitude and (b) frequency of the oscillation shown in Figure P14.8? x (cm) 10 MA 2 3 4 5 0 -5- -10- FIGURE P14.8 -t (s)
A block oscillating on a spring has a maximum kinetic energy of 2.0 J. What will be the maximum kinetic energy if the amplitude is doubled? Explain.
A block oscillating on a spring has a maximum speed of 30 cm/s. What will be the block's maximum speed if the initial elongation of the spring is doubled?
For the graph in Figure Q14.8, determine the frequency f and the oscillation amplitude A. x (cm) 10 0 -10 MA 4 2 FIGURE Q14.8 -1 (s)
What are the (a) amplitude and (b) frequency of the oscillation shown in Figure P14.9? x (cm) AA 2 6 8 20 10 0 -10 -20- FIGURE P14.9 -1 (s)
For the graph in Figure Q14.9, determine the frequency f and the oscillation amplitude A. v (cm/s) 10 0 M 2 -10 FIGURE Q14.9 4 -t (s)
An object in simple harmonic motion has an amplitude of 6.0 cm and a frequency of 0.50 Hz. Draw a position graph showing two cycles of the motion.
During an earthquake, the top of a building oscillates with an amplitude of 30 cm at 1.2 Hz. What are the magnitudes of (a) The maximum displacement, (b) The maximum velocity,(c) The maximum
Some passengers on an ocean cruise may suffer from motion sickness as the ship rocks back and forth on the waves. At one position on the ship, passengers experience a vertical motion of amplitude 1 m
Flies flap their wings at frequencies much too high for pure muscle action. A hypothesis for how they achieve these high frequencies is that the flapping of their wings is the driven oscillation of a
A passenger car traveling down a rough road bounces up and down at 1.3 Hz with a maximum vertical acceleration of 0.20 m/s2, both typical values. What are the (a) Amplitude.(b) Maximum speed of the

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