Question: A wood stove is used to heat

> Two heat engines are operated in series so that part of the energy expelled from engine A is absorbed by engine B with |QhB| = 0.750|QcA|. Engines A and B have efficiencies eA = eB = 0.250 and engine A performs work WA = 275 J. Find the overall efficienc

> A freezer has a coefficient of performance of 6.30. The freezer is advertised as using 457 kW-h/y. (a) On average, how much energy does the freezer use in a single day? (b) On average, how much thermal energy is removed from the freezer each day? (c) Wha

> A heat pump has a coefficient of performance of 3.80 and operates with a power consumption of 7.03 x 103 W. (a) How much energy does the heat pump deliver into a home during 8.00 h of continuous operation? (b) How much energy does it extract from the out

> An engine absorbs 1.70 kJ from a hot reservoir at 277°C and expels 1.20 kJ to a cold reservoir at 27°C in each cycle. (a) What is the engine’s efficiency? (b) How much work is done by the engine in each cycle? (c) What is the power output of the engine i

> A lawnmower engine ejects 1.00 x 104 J each second while running with an efficiency of 0.200. Find the engine’s horsepower rating, using the conversion factor 1 hp = 746 W.

> One of the most efficient engines ever built is a coal-fired steam turbine engine in the Ohio River valley, driving an electric generator as it operates between 1870°C and 430°C. (a) What is its maximum theoretical efficiency? (b) Its actual efficiency i

> In each cycle of its operation, a heat engine expels 2400 J of energy and performs 1800 J of mechanical work. (a) How much thermal energy must be added to the engine in each cycle? (b) Find the thermal efficiency of the engine.

> Why is it dangerous to turn on a light when you are in a bathtub?

> The work done by an engine equals one-fourth the energy it absorbs from a reservoir. (a) What is its thermal efficiency? (b) What fraction of the energy absorbed is expelled to the cold reservoir?

> A heat engine is being designed to have a Carnot efficiency of 65% when operating between two heat reservoirs. (a) If the temperature of the cold reservoir is 20°C, what must be the temperature of the hot reservoir? (b) Can the actual efficiency of the e

> A heat engine operates between a reservoir at 25°C and one at 375°C. What is the maximum efficiency possible for this engine?

> An ideal gas expands at a constant pressure of 6.00 x 105 Pa from a volume of 1.00 m3 to a volume of 4.00 m3 and then is compressed to one-third that pressure and a volume of 2.50 m3 as shown in Figure P12.32 before returning to its initial state. How mu

> A gas increases in pressure from 2.00 atm to 6.00 atm at a constant volume of 1.00 m3 and then expands at constant pressure to a volume of 3.00 m3 before returning to its initial state as shown in Figure P12.31. How much work is done in one cycle? Figur

> One mole of gas initially at a pressure of 2.00 atm and a volume of 0.300 L has an internal energy equal to 91.0 J. In its final state, the gas is at a pressure of 1.50 atm and a volume of 0.800 L, and its internal energy equals 182 J. For the paths IAF,

> A 5.0-kg block of aluminum is heated from 20°C to 90°C at atmospheric pressure. Find (a) The work done by the aluminum, (b) The amount of energy transferred to it by heat, and (c) The increase in its internal energy.

> Consider the cyclic process described by Figure P12.28. If Q is negative for the process BC and ΔU is negative for the process CA, determine the signs of Q, W, and ΔU associated with each process. Figure P12.28:

> An ideal monatomic gas is contained in a vessel of constant volume 0.200 m3. The initial temperature and pressure of the gas are 300. K and 5.00 atm, respectively. The goal of this problem is to find the temperature and pressure of the gas after 16.0 kJ

> An ideal diatomic gas expands adiabatically from 0.750 m3 to 1.50 m3. If the initial pressure and temperature are 1.50 x 105 Pa and 325 K, respectively, find (a) The number of moles in the gas, (b) The final gas pressure, (c) The final gas temperature, a

> A ski resort consists of a few chairlifts and several interconnected downhill runs on the side of a mountain, with a lodge at the bottom. The lifts are analogous to batteries, and the runs are analogous to resistors. Describe how two runs can be in serie

> An ideal monatomic gas contracts in an isobaric process from 1.25 m3 to 0.500 m3 at a constant pressure of 1.50 x 105 Pa. If the initial temperature is 425 K, find (a) The work done on the gas, (b) The change in internal energy, (c) The energy transfer Q

> An ideal gas expands at constant pressure. (a) Show that PΔV = nRΔT. (b) If the gas is monatomic, start from the definition of internal energy and show that ΔU = 3/2Wenv, where Wenv is the work done by the gas on its environment. (c) For the same monatom

> An ideal monatomic gas expands isothermally from 0.500 m3 to 1.25 m3 at a constant temperature of 675 K. If the initial pressure is 1.00 x 105 Pa, find (a) The work done on the gas, (b) The thermal energy transfer Q, and (c) The change in the internal en

> A system consisting of 0.0256 moles of a diatomic ideal gas is taken from state A to state C along the path in Figure P12.22. (a) How much work is done on the gas during this process? (b) What is the lowest temperature of the gas during this process, and

> An ideal gas is compressed from a volume of Vi = 5.00 L to a volume of Vf = 3.00 L while in thermal contact with a heat reservoir at T = 295 K as in Figure P12.21. During the compression process, the piston moves down a distance of d = 0.130 m under the

> A monatomic ideal gas undergoes the thermodynamic process shown in the PV diagram of Figure P12.20. Determine whether each of the values ΔU, Q, and W for the gas is positive, negative, or zero. Hint: The internal energy of a monatomic ideal g

> A gas is enclosed in a container fitted with a piston of cross-sectional area 0.150 m2. The pressure of the gas is maintained at 6.00 x 103 Pa as the piston moves inward 20.0 cm. (a) Calculate the work done by the gas. (b) If the internal energy of the g

> A quantity of a monatomic ideal gas undergoes a process in which both its pressure and volume are doubled as shown in Figure P12.18. What is the energy absorbed by heat into the gas during this process? Hint: The internal energy of a monatomic ideal gas

> A gas is compressed at a constant pressure of 0.800 atm from 9.00 L to 2.00 L. In the process, 400. J of energy leaves the gas by heat. (a) What is the work done on the gas? (b) What is the change in its internal energy?

> In a running event, a sprinter does 4.8 x 105 J of work and her internal energy decreases by 7.5 x 105 J. (a) Determine the heat transferred between her body and surroundings during this event. (b) What does the sign of your answer to part (a) indicate?

> An uncharged series RC circuit is to be connected across a battery. For each of the following changes, determine whether the time for the capacitor to reach 90% of its final charge would increase, decrease, or remain unchanged. Indicate your answers with

> A gas expands from I to F in Figure P12.5. The energy added to the gas by heat is 418 J when the gas goes from I to F along the diagonal path. (a) What is the change in internal energy of the gas? (b) How much energy must be added to the gas by heat for

> A cylinder of volume 0.300 m3 contains 10.0 mol of neon gas at 20.0°C. Assume neon behaves as an ideal gas. (a) What is the pressure of the gas? (b) Find the internal energy of the gas. (c) Suppose the gas expands at constant pressure to a volume of 1.00

> The only form of energy possessed by molecules of a monatomic ideal gas is translational kinetic energy. Using the results from the discussion of kinetic theory in Section 10.5, show that the internal energy of a monatomic ideal gas at pressure P and occ

> A chemical reaction transfers 1250 J of thermal energy into an ideal gas while the system expands by 2.00 x 10-2 m3 at a constant pressure of 1.50 x 105 Pa. Find the change in the internal energy.

> One mole of an ideal gas initially at a temperature of Ti = 0°C undergoes an expansion at a constant pressure of 1.00 atm to four times its original volume. (a) Calculate the new temperature Tf of the gas. (b) Calculate the work done on the gas during th

> (a) Find the work done by an ideal gas as it expands from point A to point B along the path shown in Figure P12.8. (b) How much work is done by the gas if it compressed from B to A along the same path? Figure P12.8:

> A sample of helium behaves as an ideal gas as it is heated at constant pressure from 273 K to 373 K. If 20.0 J of work is done by the gas during this process, what is the mass of helium present?

> A gas follows the PV diagram in Figure P12.6. Find the work done on the gas along the paths (a) AB, (b) BC, (c) CD, (d) DA, and (e) ABCDA. Figure P12.6:

> A gas expands from I to F along the three paths indicated in Figure P12.5. Calculate the work done on the gas along paths (a) IAF, (b) IF, and (c) IBF. Figure P12.5:

> Find the numeric value of the work done on the gas in (a) Figure P12.4a and (b) Figure P12.4b. Figure P12.4:

> There is an old admonition given to experimenters to “keep one hand in the pocket” when working around high voltages. Why is this warning a good idea?

> Gas in a container is at a pressure of 1.5 atm and a volume of 4.0 m3. What is the work done on the gas (a) If it expands at constant pressure to twice its initial volume, and (b) If it is compressed at constant pressure to one-quarter its initial volum

> Sketch a PV diagram and find the work done by the gas during the following stages. (a) A gas is expanded from a volume of 1.0 L to 3.0 L at a constant pressure of 3.0 atm. (b) The gas is then cooled at constant volume until the pressure falls to 2.0 atm.

> A balloon holding 5.00 moles of helium gas absorbs 925 J of thermal energy while doing 102 J of work expanding to a larger volume. (a) Find the change in the balloon’s internal energy. (b) Calculate the change in temperature of the gas.

> (a) Determine the work done on a fluid that expands from i to f as indicated in Figure P12.10. (b) How much work is done on the fluid if it is compressed from f to i along the same path? Figure P12.10:

> An ideal gas is enclosed in a cylinder with a movable piston on top of it. The piston has a mass of 8.00 x 103 g and an area of 5.00 cm2 and is free to slide up and down, keeping the pressure of the gas constant. (a) How much work is done on the gas as t

> Lake Erie contains roughly 4.00 x 1011 m3 of water. (a) How much energy is required to raise the temperature of that volume of water from 11.0°C to 12.0°C? (b) How many years would it take to supply this amount of energy by using the 1.00 x 104-MW exhaus

> An aluminum rod is 20.0 cm long at 20.0°C and has a mass of 0.350 kg. If 1.00 x 104 J of energy is added to the rod by heat, what is the change in length of the rod?

> The highest recorded waterfall in the world is found at Angel Falls in Venezuela. Its longest single waterfall has a height of 807 m. If water at the top of the falls is at 15.0°C, what is the maximum temperature of the water at the bottom of the falls?

> Earth’s surface absorbs an average of about 960. W/m2 from the Sun’s irradiance. The power absorbed is Pabs = (960. W/m2) (Adisc), where Adisc = πR2E is Earth’s projected area. An equal amount of power is radiated so that Earth remains in thermal equilib

> Two light-bulbs are each connected to a voltage of 120 V. One has a power of 25 W, the other 100 W. (a) Which light-bulb has the higher resistance? (b) Which light-bulb carries more current?

> If you were asked to design a capacitor in which small size and large capacitance were required, what would be the two most important factors in your design?

> Two astronauts (Fig. P8.80), each having a mass of 75.0 kg, are connected by a 10.0-m rope of negligible mass. They are isolated in space, moving in circles around the point halfway between them at a speed of 5.00 m/s. Treating the astronauts as particle

> A uniform ladder of length L and weight w is leaning against a vertical wall. The coefficient of static friction between the ladder and the floor is the same as that between the ladder and the wall. If this coefficient of static friction is μs = 0.500, d

> An object of mass M = 12.0 kg is attached to a cord that is wrapped around a wheel of radius r = 10.0 cm (Fig. P8.78). The acceleration of the object down the frictionless incline is measured to be a = 2.00 m/s2 and the incline makes an angle Î&ced

> A 40.0-kg child stands at one end of a 70.0-kg boat that is 4.00 m long (Fig. P8.77). The boat is initially 3.00 m from the pier. The child notices a turtle on a rock beyond the far end of the boat and proceeds to walk to that end to catch the turtle. (a

> Figure P8.76 shows a clawhammer as it is being used to pull a nail out of a horizontal board. If a force of magnitude 150 N is exerted horizontally as shown, find (a) The force exerted by the hammer claws on the nail and (b) The force exerted by the surf

> A 0.50-kg ball that is tied to the end of a 1.5-m light cord is revolved in a horizontal plane, with the cord making a 30° angle with the vertical. (See Fig. P7.75.) (a) Determine the ball’s speed. (b) If, instead, the ball i

> A massless spring of constant k = 78.4 N/m is fixed on the left side of a level track. A block of mass m = 0.50 kg is pressed against the spring and compresses it a distance d, as in Figure P7.74. The block (initially at rest) is then released and travel

> In a popular amusement park ride, a rotating cylinder of radius 3.00 m is set in rotation at an angular speed of 5.00 rad/s, as in Figure P7.73. The floor then drops away, leaving the riders suspended against the wall in a vertical position. What minimum

> The maximum lift force on a bat is proportional to the square of its flying speed v. For the hoary bat (Lasiurus cinereus), the magnitude of the lift force is given by The bat can fly in a horizontal circle by “bankingâ€&#15

> (a) A luggage carousel at an airport has the form of a section of a large cone, steadily rotating about its vertical axis. Its metallic surface slopes downward toward the outside, making an angle of 20.0° with the horizontal. A 30.0-kg piece of luggage i

> Blood pressure is normally measured with the cuff of the sphygmomanometer around the arm. Suppose the blood pressure is measured with the cuff around the calf of the leg of a standing person. Would the reading of the blood pressure be (a) The same here a

> A 0.275-kg object is swung in a vertical circular path on a string 0.850 m long as in Figure P7.70. (a) What are the forces acting on the ball at any point along this path? (b) Draw free-body diagrams for the ball when it is at the bottom of the circle a

> A 4.00-kg object is attached to a vertical rod by two strings as shown in Figure P7.69. The object rotates in a horizontal circle at constant speed 6.00 m/s. Find the tension in (a) The upper string and (b) The lower string. Figure P7.69:

> A coin rests 15.0 cm from the center of a turntable. The coefficient of static friction between the coin and turntable surface is 0.350. The turntable starts from rest at t = 0 and rotates with a constant angular acceleration of 0.730 rad/s2. (a) Once th

> A minimum-energy orbit to an outer planet consists of putting a spacecraft on an elliptical trajectory with the departure planet corresponding to the perihelion of the ellipse, or closest point to the Sun, and the arrival planet corresponding to the aphe

> The pilot of an airplane executes a constant-speed loopthe- loop maneuver in a vertical circle as in Figure 7.13b. The speed of the airplane is 2.00 x 102 m/s, and the radius of the circle is 3.20 x 103 m. (a) What is the pilot’s appare

> Suppose a 1800-kg car passes over a bump in a roadway that follows the arc of a circle of radius 20.4 m, as in Figure P7.65. (a) What force does the road exert on the car as the car passes the highest point of the bump if the car travels at 8.94 m/s? (b)

> A stuntman whose mass is 70 kg swings from the end of a 4.0-m-long rope along the arc of a vertical circle. Assuming he starts from rest when the rope is horizontal, find the tensions in the rope that are required to make him follow his circular path (a)

> A skier starts at rest at the top of a large hemispherical hill (Fig. P7.63). Neglecting friction, show that the skier will leave the hill and become airborne at a distance h = R/3 below the top of the hill. Figure P7.63:

> Casting of molten metal is important in many industrial processes. Centrifugal casting is used for manufacturing pipes, bearings, and many other structures. A cylindrical enclosure is rotated rapidly and steadily about a horizontal axis, as in Figure P7.

> In a home laundry dryer, a cylindrical tub containing wet clothes is rotated steadily about a horizontal axis, as shown in Figure P7.61. So that the clothes will dry uniformly, they are made to tumble. The rate of rotation of the smooth-walled tub is cho

> Several common barometers are built using a variety of fluids. For which fluid will the column of fluid in the barometer be the highest? (Refer to Table 9.1.) Table 9.1: (a) Mercury (b) Water (c) Ethyl alcohol (d) Benzene

> Each of the following objects has a radius of 0.180 m and a mass of 2.40 kg, and each rotates about an axis through its center (as in Table 8.1) with an angular speed of 35.0 rad/s. Find the magnitude of the angular momentum of each object. (a) A hoop (b

> A 2.00-kg solid, uniform ball of radius 0.100 m is released from rest at point A in Figure P8.59, its center of gravity a distance of 1.50 m above the ground. The ball rolls without slipping to the bottom of an incline and back up to point B where it is

> Use conservation of energy to determine the angular speed of the spool shown in Figure P8.58 after the 3.00-kg bucket has fallen 4.00 m, starting from rest. The light string attached to the bucket is wrapped around the spool and does not slip as it unwin

> A 10.0- kg cylinder rolls without slipping on a rough surface. At an instant when its center of gravity has a speed of 10.0 m/s, determine (a) The translational kinetic energy of its center of gravity, (b) The rotational kinetic energy about its center o

> A constant torque of 25.0 N · m is applied to a grindstone whose moment of inertia is 0.130 kg · m2. Using energy principles and neglecting friction, find the angular speed after the grindstone has made 15.0 revolutions. Hint: The angular equivalent of W

> The top in Figure P8.55 has a moment of inertia of 4.00 = 10-4 kg · m2 and is initially at rest. It is free to rotate about a stationary axis AA´. A string wrapped around a peg along the axis of the top is pulled in such a mann

> A car is designed to get its energy from a rotating solid- disk flywheel with a radius of 2.00 m and a mass of 5.00 = 102 kg. Before a trip, the flywheel is attached to an electric motor, which brings the flywheel’s rotational speed up to 5.00 = 103 rev/

> A solid, uniform disk of radius 0.250 m and mass 55.0 kg rolls down a ramp of length 4.50 m that makes an angle of 15.0° with the horizontal. The disk starts from rest from the top of the ramp. Find (a) The speed of the disk’s center of mass when it reac

> A 240-N sphere 0.20 m in radius rolls without slipping 6.0 m down a ramp that is inclined at 37° with the horizontal. What is the angular speed of the sphere at the bottom of the slope if it starts from rest?

> A light rod of length â„“ = 1.00 m rotates about an axis perpendicular to its length and passing through its center as in Figure P8.51. Two particles of masses m1 = 4.00 kg and m2 = 3.00 kg are connected to the ends of the rod. (a) Neglec

> The pressure at the bottom of a glass filled with water (p = 1000 kg/m3) is P. The water is poured out and the glass is filled with ethyl alcohol (p = 806 kg/m3). The pressure at the bottom of the glass is now (a) Smaller than P (b) Equal to P (c) Larger

> Four objects—a hoop, a solid cylinder, a solid sphere, and a thin, spherical shell—each have a mass of 4.80 kg and a radius of 0.230 m. (a) Find the moment of inertia for each object as it rotates about the axes shown

> A horizontal 800.-N merry-go-round of radius 1.50 m is started from rest by a constant horizontal force of 50.0 N applied tangentially to the merry-go-round. Find the kinetic energy of the merry-go-round after 3.00 s. (Assume it is a solid cylinder.)

> A 2.50-kg solid, uniform disk rolls without slipping across a level surface, translating at 3.75 m/s. If the disk’s radius is 0.100 m, find its (a) Translational kinetic energy and (b) Rotational kinetic energy.

> The uniform thin rod in Figure P8.47 has mass M = 3.50 kg and length L = 1.00 m and is free to rotate on a frictionless pin. At the instant the rod is released from rest in the horizontal position, find the magnitude of (a) The rod’s an

> An Atwood’s machine consists of blocks of masses m1 = 10.0 kg and m2 = 20.0 kg attached by a cord running over a pulley as in Figure P8.46. The pulley is a solid cylinder with mass M = 8.00 kg and radius r = 0.200 m. The block of mass m

> A 150.- kg merry - go - round in the shape of a uniform, solid, horizontal disk of radius 1.50 m is set in motion by wrapping a rope about the rim of the disk and pulling on the rope. What constant force must be exerted on the rope to bring the merry - g

> A bicycle wheel has a diameter of 64.0 cm and a mass of 1.80 kg. Assume that the wheel is a hoop with all the mass concentrated on the outside radius. The bicycle is placed on a stationary stand, and a resistive force of 120 N is applied tangent to the r

> A model airplane with mass 0.750 kg is tethered by a wire so that it flies in a circle 30.0 m in radius. The airplane engine provides a net thrust of 0.800 N perpendicular to the tethering wire. (a) Find the torque the net thrust produces about the cente

> A potter’s wheel having a radius of 0.50 m and a moment of inertia of 12 kg · m2 is rotating freely at 50 rev/min. The potter can stop the wheel in 6.0 s by pressing a wet rag against the rim and exerting a radially inward force of 70 N. Find the effecti

> An approximate model for a ceiling fan consists of a cylindrical disk with four thin rods extending from the disk’s center, as in Figure P8.41. The disk has mass 2.50 kg and radius 0.200 m. Each rod has mass 0.850 kg and is 0.750 m long

> Suppose you have one cubic meter of gold, two cubic meters of silver, and six cubic meters of aluminum. Rank them by mass, from smallest to largest. (a) Gold, aluminum, silver (b) Gold, silver, aluminum (c) Aluminum, gold, silver (d) Silver, aluminum, go

> An oversized yo-yo is made from two identical solid disks each of mass M = 2.00 kg and radius R = 10.0 cm. The two disks are joined by a solid cylinder of radius r = 4.00 cm and mass m = 1.00 kg as in Figure P8.40. Take the center of the cylinder as the

> A large grinding wheel in the shape of a solid cylinder of radius 0.330 m is free to rotate on a frictionless, vertical axle. A constant tangential force of 250. N applied to its edge causes the wheel to have an angular acceleration of 0.940 rad/s2. (a)

> If the system shown in Figure P8.37 is set in rotation about each of the axes mentioned in Problem 37, find the torque that will produce an angular acceleration of 1.50 rad/s2 in each case. Axes From Problem 37: (a) The x-axis, (b) The y-axis, and (c) A

> Four objects are held in position at the corners of a rectangle by light rods as shown in Figure P8.37. Find the moment of inertia of the system about (a) The x-axis, (b) The y-axis, and (c) An axis through O and perpendicular to the page. Figure P8.37: