Question: The thermal conductivities of human tissues vary

> An emf of 10 V is connected to a series RC circuit consisting of a resistor of 2.0 x 106 Ω and an initially uncharged capacitor of 3.0 μF. Find the time required for the charge on the capacitor to reach 90% of its final value.

> A dead battery is charged by connecting it to the live battery of another car with jumper cables (Fig. P18.28). Determine the current in (a) The starter and in (b) The dead battery. Figure P18.28:

> (a) Can the circuit shown in Figure P18.27 be reduced to a single resistor connected to the batteries? Explain. (b) Calculate each of the unknown currents I1, I2, and I3 for the circuit. Figure P18.27:

> Figure P18.26 shows a voltage divider, a circuit used to obtain a desired voltage ΔVout from a source voltage ε. Determine the required value of R2 if ε = 5.00 V, ΔVout = 1.50 V, and R1 = 1.00 x 103 &Icir

> Using Kirchhoff’s rules, (a) Find the current in each resistor shown in Figure P18.25 and (b) Find the potential difference between points c and f. Figure P18.25:

> Four resistors are connected to a battery with a terminal voltage of 12 V, as shown in Figure P18.24. (a) How would you reduce the circuit to an equivalent single resistor connected to the battery? Use this procedure to find the equivalent resistance of

> In the circuit of Figure P18.23, determine (a) The current in each resistor, (b) The potential difference across the 2.00 x 102 - Ω resistor, and (c) The power delivered by each battery. Figure P18.23:

> In the circuit of Figure P18.22, the current I1 is 3.0 A and the values of ε and R are unknown. What are the currents I2 and I3? Figure P18.22:

> Taking R = 1.00 kΩ and ε = 250. V in Figure P18.21, determine the direction and magnitude of the current in the horizontal wire between a and e. Figure P18.21:

> For the circuit shown in Figure P18.20, calculate (a) The current in the 2.00 - Ω resistor and (b) The potential difference between points a and b, ΔV = Vb – V. Figure P18.20:

> Figure P18.19 shows a Wheatstone bridge, a circuit used to precisely measure an unknown resistance R by varying Rvar until the ammeter reads zero current and the bridge is said to be “balanced.” If the bridge is balanc

> The circuit in Figure P18.55 has been connected for several seconds. Find the current (a) In the 4.00 - V battery, (b) In the 3.00 - Ω resistor, (c) In the 8.00 - V battery, and (d) In the 3.00 - V battery. (e) Find the charge on the capacito

> (a) Find the current in each resistor of Figure P18.18 by using the rules for resistors in series and parallel. (b) Write three independent equations for the three currents using Kirchhoff’s laws: one with the node rule; a second using

> (a) You need a 45 - Ω resistor, but the stockroom has only 20. - Ω and 50. - Ω resistors. How can the desired resistance be achieved under these circumstances? (b) What can you do if you need a 35 - Ω resistor?

> (a) Is it possible to reduce the circuit shown in Figure P18.16 to a single equivalent resistor connected across the battery? Explain. (b) Find the current in the 2.00 - Ω resistor. (c) Calculate the power delivered by the battery to the circ

> Find the current in the 12 - Ω resistor in Figure P18.15. Figure P18.15:

> A 2.00 - nF capacitor with an initial charge of 5.10 μC is discharged through a 1.30 – kΩ resistor. (a) Calculate the magnitude of the current in the resistor 9.00 μs after the resistor is connected across the terminals of the capacitor. (b) What charge

> The given pair of capacitors in Figure P18.67 is fully charged by a 12.0 - V battery. The battery is disconnected and the circuit closed. After 1.00 ms, how much charge remains on (a) The 3.00 - μF capacitor? (b) The 2.00 - μF

> Consider the two arrangements of batteries and bulbs shown in Figure P18.66. The two bulbs are identical and have resistance R, and the two batteries are identical with output voltage ΔV. (a) In case 1, with the two bulbs in series, compare t

> What are the expected readings of the ammeter and voltmeter for the circuit in Figure P18.65? Figure P18.65:

> In Figure P18.64, R1 = 0.100 Ω, R2 = 1.00 Ω, and R3 = 10.0 Ω. Find the equivalent resistance of the circuit and the current in each resistor when a 5.00 - V power supply is connected between (a) Points A and B, (b) Poi

> An electric eel generates electric currents through its highly specialized Hunter’s organ, in which thousands of disk - shaped cells called electrocytes are lined up in series, very much in the same way batteries are lined up inside a flashlight. When ac

> The resistance between points a and b in Figure P18.54 drops to one - half its original value when switch S is closed. Determine the value of R. Figure P18.54:

> Three liquids are at temperatures of 10°C, 20°C, and 30°C, respectively. Equal masses of the first two liquids are mixed, and the equilibrium temperature is 17°C. Equal masses of the second and third are then mixed, and the equilibrium temperature is 28°

> An automobile has a mass of 1500 kg, and its aluminum brakes have an overall mass of 6.00 kg. (a) Assuming all the internal energy transformed by friction when the car stops is deposited in the brakes and neglecting energy transfer, how many times could

> An iron plate is held against an iron wheel so that a sliding frictional force of 50. N acts between the two pieces of metal. The relative speed at which the two surfaces slide over each other is 40. m/s. (a) Calculate the rate at which mechanical energy

> A bar of gold (Au) is in thermal contact with a bar of silver (Ag) of the same length and area (Fig. P11.63). One end of the compound bar is maintained at 80.0°C, and the opposite end is at 30.0°C. Find the temperature at the juncti

> A class of 10 students taking an exam has a power output per student of about 200 W. Assume the initial temperature of the room is 20°C and that its dimensions are 6.0 m by 15.0 m by 3.0 m. What is the temperature of the room at the end of 1.0 h if all t

> Liquid helium has a very low boiling point, 4.2 K, as well as a very low latent heat of vaporization, 2.00 x 104 J/kg. If energy is transferred to a container of liquid helium at the boiling point from an immersed electric heater at a rate of 10.0 W, how

> Overall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2430 kJ/kg), evaporation from the lungs (38 kJ/h), conduction, and conv

> The temperature of a silver bar rises by 10.0°C when it absorbs 1.23 kJ of energy by heat. The mass of the bar is 525 g. Determine the specific heat of silver from these data.

> A student measures the following data in a calorimetry experiment designed to determine the specific heat of aluminum: Initial temperature of water and calorimeter: 70.0°C Mass of water: 0.400 kg Mass of calorimeter: 0.040 kg Specific heat of

> The surface area of an unclothed person is 1.50 m2, and his skin temperature is 33.0°C. The person is located in a dark room with a temperature of 20.0°C, and the emissivity of the skin is e = 0.95. (a) At what rate is energy radiated by the body? (b) Wh

> In an analogy between traffic flow and electrical current, (a) What would correspond to the charge Q? (b) What would correspond to the current I?

> A 0.040.-kg ice cube floats in 0.200 kg of water in a 0.100-kg copper cup; all are at a temperature of 0°C. A piece of lead at 98°C is dropped into the cup, and the final equilibrium temperature is 12°C. What is the mass of the lead?

> A family comes home from a long vacation with laundry to do and showers to take. The water heater has been turned off during the vacation. If the heater has a capacity of 50.0 gallons and a 4800-W heating element, how much time is required to raise the t

> The bottom of a copper kettle has a 10.0-cm radius and is 2.00 mm thick. The temperature of the outside surface is 102°C, and the water inside the kettle is boiling at 1 atm of pressure. Find the rate at which energy is being transferred through the bott

> The filament of a 75-W light bulb is at a temperature of 3300 K. Assuming the filament has an emissivity e = 1.0, find its surface area.

> Measurements on two stars indicate that Star X has a surface temperature of 5727°C and Star Y has a surface temperature of 11727°C. If both stars have the same radius, what is the ratio of the luminosity (total power output) of Star Y to the luminosity o

> A granite ball of radius 2.00 m and emissivity 0.450 is heated to 135°C. (a) Convert the given temperature to Kelvin. (b) What is the surface area of the ball? (c) If the ambient temperature is 25.0°C, what net power does the ball radiate?

> A rectangular glass window pane on a house has a width of 1.0 m, a height of 2.0 m, and a thickness of 0.40 cm. Find the energy transferred through the window by conduction in 12 hours on a day when the inside temperature of the house is 22°C and the out

> A Styrofoam box has a surface area of 0.80 m2 and a wall thickness of 2.0 cm. The temperature of the inner surface is 5.0°C, and the outside temperature is 25°C. If it takes 8.0 h for 5.0 kg of ice to melt in the container, determine the thermal conducti

> A person’s basal metabolic rate (BMR) is the rate at which energy is expended while resting in a neutrally temperate environment. A typical BMR is 7.00 x 106 J/day. Convert this BMR to units of (a) Watts and (b) Kilocalories (or Calories) per hour. (c) S

> A copper rod and an aluminum rod of equal diameter are joined end to end in good thermal contact. The temperature of the free end of the copper rod is held constant at 100.°C and that of the far end of the aluminum rod is held at 0°C. If the copper rod i

> A 12 - V battery is connected across a device with variable resistance. As the resistance of the device increases, determine whether the following quantities increase, decrease, or remain unchanged. Indicate your answers with I, D, or U, respectively. (a

> A thermopane window consists of two glass panes, each 0.50 cm thick, with a 1.0-cm-thick sealed layer of air in between. (a) If the inside surface temperature is 23°C and the outside surface temperature is 0.0°C, determine the rate of energy transfer thr

> Consider two cooking pots of the same dimensions, each containing the same amount of water at the same initial temperature. The bottom of the first pot is made of copper, while the bottom of the second pot is made of aluminum. Both pots are placed on a h

> The average thermal conductivity of the walls (including windows) and roof of a house in Figure P11.46 is 4.8 x 10-4 kW/m · °C, and their average thickness is 21.0 cm. The house is heated with natural gas, with a heat of combusti

> A steam pipe is covered with 1.50-cm-thick insulating material of thermal conductivity 0.200 cal/cm · °C · s. How much energy is lost every second when the steam is at 200.°C and the surrounding air is at 20.0 °C? The pipe has a circumference of 800. cm

> A pond with a flat bottom has a surface area of 820 m2 and a depth of 2.0 m. On a warm day, the surface water is at a temperature of 25°C, while the bottom of the pond is at 12°C. Find the rate at which energy is transferred by conduction from the surfac

> A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.0 m x 2.0 m. On a certain day, the indoor temperature is 25°C and the outdoor temperature is 0°C. (a) What is the rate at which energy is transferred by heat through the glass? (b) How

> The plates of a capacitor are connected to a battery. (a) What happens to the charge on the plates if the connecting wires are removed from the battery? (b) What happens to the charge if the wires are removed from the battery and connected to each other?

> If you are given three different capacitors C1, C2, and C3, how many different combinations of capacitance can you produce, using all capacitors in your circuits?

> Consider point A in Figure CQ15.8 located an arbitrary distance from two point charges in otherwise empty space. (a) Is it possible for an electric field to exist at point A in empty space? (b) Does charge exist at this point? (c) Does a force exist at t

> If a suspended object A is attracted to a charged object B, can we conclude that A is charged? Explain.

> A 3.00-g lead bullet at 30.0°C is fired at a speed of 2.40 x 102 m/s into a large, fixed block of ice at 0°C, in which it becomes embedded. (a) Describe the energy transformations that occur as the bullet is cooled. What is the final temperature of the b

> Two uncharged, conducting spheres are separated by a distance d. When charge -Q is moved from sphere A to sphere B, the Coulomb force between them has magnitude F0. (a) Is the Coulomb force attractive or repulsive? (b) If an additional charge -Q is moved

> The fundamental charge is e = 1.60 x 10-19 C. Identify whether each of the following statements is true or false. (a) It’s possible to transfer electric charge to an object so that its net electric charge is 7.5 times the fundamental electric charge, e.

> A student who grew up in a tropical country and is studying in the United States may have no experience with static electricity sparks and shocks until his or her first American winter. Explain.

> A spherical surface surrounds a point charge q. Describe what happens to the total flux through the surface if (a) The charge is tripled, (b) The volume of the sphere is doubled, (c) The surface is changed to a cube, (d) The charge is moved to another lo

> A bat flying at 5.00 m/s is chasing an insect flying in the same direction. If the bat emits a 40.0-kHz chirp and receives back an echo at 40.4 kHz, (a) What is the speed of the insect? (b) Will the bat be able to catch the insect? Explain.

> Why should a ground wire be connected to the metal support rod for a television antenna?

> In fair weather, there is an electric field at the surface of the Earth, pointing down into the ground. What is the sign of the electric charge on the ground in this situation?

> Each of the following statements is related to standing waves on a string. Choose the words that make each statement correct. (i) The harmonic number is equal to the number of [(a) nodes; (b) antinodes]. (ii) The distance from a node to its adjacent anti

> Why does a vibrating guitar string sound louder when placed on the instrument than it would if allowed to vibrate in the air while off the instrument?

> Explain how the distance to a lightning bolt (Fig. CQ14.4) can be determined by counting the seconds between the flash and the sound of thunder. Fig CQ14.4:

> The excess internal energy of metabolism is exhausted through a variety of channels, such as through radiation and evaporation of perspiration. Consider another pathway for energy loss: moisture in exhaled breath. Suppose you breathe out 22.0 breaths per

> When dealing with sound intensities and decibel levels, a convenient approximation (accurate to 2 significant figures) is: For every doubling of the intensity, the decibel level increases by 3.0. Suppose the sound level at some location is 85 dB. Find th

> A soft drink bottle resonates as air is blown across its top. What happens to the resonant frequency as the level of fluid in the bottle decreases?

> A block connected to a horizontal spring is in simple harmonic motion on a level, frictionless surface, oscillating with amplitude A around x = 0. Identify whether each of the following statements is true or false: (a) If x = (A then |v|=|vmax| and |a|=|

> If a spring is cut in half, what happens to its spring constant?

> If the spring constant shown in Figure CQ13.3 is doubled to 2k0, determine (a) The ratio of the new force to the original force, Fn/F0, and (b) The ratio of the new to the original elastic potential energy, PEsn/PEs0. Figure CQ13.3:

> If an object – spring system is hung vertically and set into oscillation, why does the motion eventually stop?

> Identify each of the following waves as either transverse or longitudinal: (a) The waves on a plucked guitar string. (b) The sound waves produced by a vibrating guitar string. (c) The waves on a spring with its end pumped back and forth along the spring’

> If you stretch a rubber hose and pluck it, you can observe a pulse traveling up and down the hose. What happens to the speed of the pulse if you stretch the hose more tightly? What happens to the speed if you fill the hose with water?

> If a grandfather clock were running slow, how could we adjust the length of the pendulum to correct the time?

> A thermodynamic process occurs in which the entropy of a system changes by -6 J/K. According to the second law of thermodynamics, what can you conclude about the entropy change of the environment? (a) It must be +6 J/K or less. (b) It must be equal to 6

> A 55-kg student eats a 540-Calorie (540 kcal) jelly doughnut for breakfast. (a) How many joules of energy are the equivalent of one jelly doughnut? (b) How many stairs must the student climb to perform an amount of mechanical work equivalent to the food

> Power P0 = I0 ΔV0 is delivered to a resistor of resistance R0. If the resistance is doubled (Rnew = 2R0) while the voltage is adjusted such that the current is constant, what are the ratios (a) Pnew/P0 and (b) ΔVnew/ΔV0? If, instead, the resistance is he

> Star A has twice the radius and twice the absolute temperature of star B. What is the ratio of the power output of star A to that of star B? The emissivity of both stars can be assumed to be 1. (a) 4 (b) 8 (c) 16 (d) 32 (e) 64

> What is wrong with the following statement: “Given any two bodies, the one with the higher temperature contains more heat.”

> On a very hot day, it’s possible to cook an egg on the hood of a car. Would you select a black car or a white car on which to cook your egg? Why?

> Objects A and B with TA > TB are placed in thermal contact and come to equilibrium. (a) For which object does the entropy increase? (b) For which object does the entropy decrease? (c) Which object has the greater magnitude of entropy change?

> Objects A and B have the same size and shape with emissivities eA and eB and temperatures TA and TB, respectively. (a) If eA = eB and TB = 4TA, what is the ratio PB /PA of their radiated powers? (b) If, instead, they radiate the same power and eA = 4eB,

> The first law of thermodynamics is ΔU = Q + W. For each of the following cases, state whether the internal energy of an ideal gas increases, decreases, or remains constant: (a) No energy is transferred to the gas as it expands to twice its original volum

> In a calorimetry experiment, three samples A, B, and C with TA > TB > TC are placed in thermal contact. When the samples have reached thermal equilibrium at a common temperature T, which one of the following must be true? (a) QA > QB > QC (b) QA < 0, QB

> A heat engine does work Weng while absorbing energy Qh from the hot reservoir and expelling energy Qc to the cold reservoir. Which one of the following is impossible? (a) |Qh| > |Qc| > Weng (b) |Qh| > Weng > |Qc| (c) |Qh| > Weng = |Qc| (d) Weng > |Qh| (e

> The U.S. penny is now made of copper-coated zinc. Can a calorimetric experiment be devised to test for the metal content in a collection of pennies? If so, describe the procedure.

> An ideal gas undergoes an adiabatic process so that no energy enters or leaves the gas by heat. Which one of the following statements is true? (a) Because no energy is added by heat, the temperature cannot change. (b) The temperature increases if the gas

> Steam at 100.°C is added to ice at 0°C. (a) Find the amount of ice melted and the final temperature when the mass of steam is 10. g and the mass of ice is 50. g. (b) Repeat with steam of mass 1.0 g and ice of mass 50. g.

> Different amounts of thermal energy are added to each of three isolated samples A, B, and C of lead. If the energy transfers are ordered as QB > QC > QA and each sample undergoes the same temperature change, which sample has the largest mass?

> Clearly distinguish among temperature, heat, and internal energy.

> Equal masses of substance A at 10.0°C and substance B at 90.0°C are placed in a well-insulated container of negligible mass and allowed to come to equilibrium. If the equilibrium temperature is 75.0°C, which substance has the larger specific heat? (a) Su

> Which one of the following statements is true? (a) The path on a PV diagram always goes from the smaller volume to the larger volume. (b) The path on a PV diagram always goes from the smaller pressure to the larger pressure. (c) The area under the path o

> On a clear, cold night, why does frost tend to form on the tops, rather than the sides, of mailboxes and cars?

> For each of the following temperatures, find the equivalent temperature on the indicated scale: (a) -273.15°C on the Fahrenheit scale, (b) 98.6°F on the Celsius scale, and (c) 1.00 x 102 K on the Fahrenheit scale.

> Calculate the slopes for the A, C, and E portions of Figure 11.3. Rank the slopes from least to greatest and explain what your ranking means. (a) A, C, E (b) C, A, E (c) E, A, C (d) E, C, A Figure 11.3:

> Suppose you have 1 kg each of iron, glass, and water, and all three samples are at 10°C. (a) Rank the samples from lowest to highest temperature after 100 J of energy is added to each by heat. (b) Rank them from least to greatest amount of energy transfe

> The switch is closed in Figure 18.20. After a long time compared with the time constant of the circuit, what will the current be in the 2 - &Icirc;&copy; resistor? (a) 4 A (b) 3 A (c) 2 A (d) 1 A (e) More information is needed. Figure 18.20:

> If the light-bulbs in Quick Quiz 18.7 are connected one by one in series instead of in parallel, what happens to (a) The brightness of the light-bulbs? (b) The individual currents in the light-bulbs? (c) The power delivered by the battery? (d) The lifeti