What happens to the internal energy of 5jw-v qb 4-am:s:- z*rqgq tsdwater vapor in the air that condenses on the outside of a cold glass of water? Is :s5 j4r*sv abqg:m-d-q qzwt-work done or heat exchanged? Explain.

Use the conservation of energy to ex 3zae4j(0ij2 kto)-u(bcsjejplain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases teb4( ju)sj0-i j jk2 e(cao3zwhen the gas expands.

In an isothermal process, 3700 J of work is done by an ido ht;cb:0pi ;real gas. Is this enough information to tell how much hetcbpih : ;r;0oat has been added to the system? If so, how much?

Is it possible for the temp(y x7zm8phqj i 9wbc.buf29x/5 x(iuv erature of a system to remain constant even though heat flow qz7xb 92/j pi.( yucx5m b9uwvh8i(xfs into or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when b fv0u,5tyl k/it is adiabatically compressed.f/ 5,v ykltb0u

Can mechanical energy ever be transform7ic(ug)8oi/bze r c9l ed completely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yeli/97ib( zu)og e8crcs, give one or two examples.

Can you warm a kitchen in ;-egq 2r);uwndk5f fvwinter by leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door open? Exdgfe-nfu5 ; w;vk)r2 qplain.

Would a definition of heat engine efficiency 9ogapx5dt 26w as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature antpkh 5;evm1u 6d low-temperature areas in (a) an internalk5pv1;ute h6m combustion engine, and (b) a steam engine?

Which will give the greater improvement in the efficqy39.uf3 bffmzfe) lw(x-7 wqiency of a Carnot engine, a 103q)we.xff(-m3bw 9 lfu z qfy7 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous amount of thermal (internal) eue xrd kusm wlib9*ip/h);n-k3 ))6 ylnergy. Why, in general, is it not possible to put this eel );xyr)3mw 6uus/kni 9kbdi-l*ph) nergy to useful work?

A gas is allowed to expand (a) adiabatically ans;p f .s(wvugz,mbeu18nq *y9 d (b) isothermally. In each process, does the entropy increase, dec ,vuz1;*fseywg9bp. u(mq 8snrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabaticaoxu akld04( k1+tjj)ylly or isothermally. Whi u1kao)ydx(j+j0 k4ltch process would result in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Ch99wa*vv9hfwh p nv08lapter, of naturally occurring processes in which order goes to disorder. Discuss the observability of the reversew*lw hvhp90vnaf v89 9 process.

Which do you think has the greater entropy, 1 kg of solid ir 6 5fx.mm6zrfqr)wlu* on or 1 kg of liquidl z x)ffr6*qr 5mwm.u6 iron? Why?

(a) What happens if you remove the lid of a bottle containing chlorine gas? (b))j;suf4ual u6yt6dt6o0 ja.z Does the reverse process eve6 l 4ua z.s;fyajd 6)60tjotuur happen? Why or why not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-room airyh5ptr1ky6u dy/o (h9x9,vj hsx3jo + conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air yyo1kjo/ ph d,9j hy63r (v5xusxt+9hcoming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than those already me1.y gbq:csk,zq ii w/7ntioned) that would obey the first law of thermodynamics, bu7/ 1iwkg z y.s:qqib,ct, if they actually occurred, would violate the second law.

Suppose a lot of papers are sp2xu /p4+kep8hvd:b7ttj:dj trewn all over the floor; then you stack them neatly. Does this violate the second law of thermodynamics? Explain.vkejp+h 2tjd8p: /t du 7pbx4:

The first law of thermodynamics isd2 usw +3q:/.erzp1kc ko ms/s sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how these statem1kcd2s:e./3 ruqmk s+ so pw/zents could be equivalent to the formal statements.

Entropy is often called “time’s arrow” b2iof01q.fxo . bry 0nbecause it tells us in which direction natural processes occur. If a movie were run backward, name some processes that you might seei x1 bfnq0fb o.0ro.y2 that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simple food molecw0qz3o( o3 4q spjhkpuq:, 8lgules into a complex structure. Iqk8: pj4pu h3q03l owqz(g ,oss this a violation of the second law of thermodynamics?

  An ideal gas expandspk0t -z/e66 hqdqlo,n isothermally, performing $ 3.40\times10^{ 3}J$ of work in the process. Calculate
(a) the change in internal energy of the gas,
(b) the heat absorbed during this expansion.    $J$

  A gas is enclosed in a cylinder fitted with a light frictionless pistf +el4 ,yp3q8ik dh3rton and maintained at atmospheric pressure. When 1400 k rli4 hdfk,t ep3q38+ycal of heat is added to the gas, the volume is observed to increase slowly from $12m^3$ to $18.2m^3$ Calculate
(a) the work done by the gas .   $ \times10^{5 }$
(b) the change in internal energy of the gas.    $ \times10^{ 6}$

One liter of air is cooled at constant pressure until it,cfkvwngzy,. 3q ih-u q299gp xc :cw6s volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the prou .wxn gck2 3zqh 9,iqg:c69f ,ywp-cvcess on a PV diagram.

Sketch a PV diagram of the following procey;97rbdmj 7 ; jplf.botgt.4 jss: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.;9olb d.tjm 7bjpr ft 4;jg7y.0 L, whereupon the pressure is increased at constant volume until the original pressure is reached.

A 1.0-L volume of air initiallypt4q5klt //bks rji5 - at 4.5 atm of (absolute) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, and lastly is brought back to its original pressure by heating at constant volume. Draw the process on a PV diagram, including numbers and lab55 jkqisrt pk /b4tl-/els for the axes.

  The pressure in an ideat4(.o2 bvi.xurz qlv 0j*awm0l gas is cut in half slowly, while being kept in a container with rigid walls. In thxvj aqzowrum v(0l* t.04i. 2be process, 265 kJ of heat left the gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas iv58s+ k/ hzr3w8 mxixhs compressed adiabatically to half its volume. In doing so, 1850 J of work is dmxxk+3z hhw8i8vrs5 / one on the gas.
(a) How much heat flows into or out of the gas?    $J$
(b) What is the change in internal energy of the gas?    $J$
(c) Does its temperature rise or fall? ----待选择----fallrise 

  An ideal gas expands at a constant total pressure of 3.0 atm :4 )i ox*5sp n5vueszzfrom 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until the temperature reaches its original value. Calcul5 5z:pnxs* ue4zv )iosate
(a) the total work done by the gas in the process,   $J$
(b) the total heat flow into the gas.    $J$

  One and one-half moles of an ideal monatomic gas e-alc po,* c j6ydm)lukv 6o..bxpand adiabatically, performing 7500 J of work in the process. What is the change in tempe p*mck, j-l.l.u6od) cavy6borature of the gas during this expansion?   $ K$

  Consider the following two-step process. m9j )h76jupjnHeat is allowed to flow out of an ideal gas at constant volum jjm6p9n7ju h)e so that its pressure drops from 2.2 atm to 1.4 atm. Then the gas expands at constant pressure, from a volume of 6.8 L to 9.3 L, where the temperature reaches its original value. See Fig. 15–22. Calculate
(a) the total work done by the gas in the process,    $J$
(b) the change in internal energy of the gas in the process,    $J$
(c) the total heat flow into or out of the gas.    $J$  ----待选择----intoout  the gas

  The PV diagram in Fig. 15–23 shows two possible statz- z,fssm:py-3xjgt d3k /r1ees of a system containing 1.35 moles of a monatomic idea tse/j1f:y-dmzs- 3,k g3xrzpl gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to c along the curved path in F(duo-hsspf7,(gp9 sl mi w7spx1d,*uig. 15–24, the work done by the gx,(wgd*, (i 9s7 o fplmsspdh 17uspu-as is $W\,=\,-35\,J$ and the heat added to the gas is $Q\,=\,-63\,J$ Along path abc, the work done is $W\,=\,-48\,J$
(a) What is Q for path abc?    $J$
(b) If $P_c\,=\,\frac{1}{2}P_b$ what is W for path cda?    $J$
(c) What is Q for path cda?    $J$
(d) What is $U_a-U_c$?    $J$
(e) If $U_d-U_c\,=\,5J$ what is Q for path da?    $J$

  In the process of taking a gas from state a to state c along the curved path sho)-, axwyu1 + ej-aaarpwn in Fig. 15–24, 80 aj)awa a e,1py-+- urxJ of heat leaves the system and 55 J of work is done on the system.
(a) Determine the change in internal energy, $U_a-U_c$.    $J$
(b) When the gas is taken along the path cda, the work done by the gas is How much heat Q is added to the gas in the process cda?    $J$
(c) If $ P_a\,=\,2.5P_d$ how much work is done by the gas in the process abc?    $J$
(d) What is Q for path abc?    $J$
(e) If $U_a-U_b\,=\,10\,J$ what is Q for the process bc?    $J$
Here is a summary of what is given:
$\begin{aligned}
Q_{\mathrm{a} \rightarrow \mathrm{c}} & =-80 \mathrm{~J} \\
W_{\mathrm{a} \rightarrow \mathrm{c}} & =-55 \mathrm{~J} \\
W_{\mathrm{cda}} & =38 \mathrm{~J} \\
U_{\mathrm{a}}-U_{\mathrm{b}} & =10 \mathrm{~J} \\
P_{\mathrm{d}} & =2.5 P_{\mathrm{d}} .
\end{aligned}$

  How much energy would the person of Example 15–8 transform ik u n)6w m.y(m vek4f1. pz5bp-8awqcof instead of working 11.0 h she took a noontim4nwp(v6 -bo8m ).wk5pu1 cae.yzmqkfe break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who x(qxkacu3 1t. sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches televisio 3xt1quxc .ak(n 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleepinl+ft , e(lpmkp)c a1o/g one hour less per day, using the time for light activity. How much weight (or mass) can this person expect to lose in 1 year, assuming no change in food intake? Assume that 1 kg of fat stores abou (p/o)1lf lca+p,tmekt 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while perpy ,ajbj ( )3n-qgr7bkkb.b 9tforming 3200 J of useful work. What is the efficiency of t by pr bbtkjn3g. 7q(b)9k,-ajhis engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal o-1 3gya:c t2 bp2bki/.ibb whvf heat from a high-temperature reservoir. Ww2v /2gp-1b3.babick:ybth ihat is the efficiency of this engine?    %

  What is the maximum efficiency of c ehu9lg7mv;2- l3ey;4esi wg5goc-pa heat engine whose operating temperatures areogl592w; 3u i 4 gsg7c velem-ec;y-hp 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat en5cxp c2+v w7xcw qia8f-1 ug/reyho/)gine is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operate).d gbib.kx( us at 75% of its maximum theoretical (Carnot) efficiency be.( i)bxbku.dgtween temperatures of 625$^{\circ}\,C$ and 350$^{\circ}\,C$. If the plant produces electric energy at the rate of 1.3 GW, how much exhaust heat is discharged per hour?    $ \times10^{13 }J/h$

  It is not necessary that a heat engine’s hot environwj4n: yhy)2 54iey,r hjrgj q,ment be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the efficiency of an engine that made use of heat transferred fro qh5gji, j rynw4)reh4j,y2:ym air at room temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine perfrw9nppryj 8xsf/ bzmue - xn0(1) d/0morms work at the rate of 440 kW while using 680 kcal of heat pe/mz-bu/py re)swxj xrn(810m9fpd n 0r second. If the temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operati-,ezhsv mfj jw);u:7gt/h td ,ng temperatures are 210$^{\circ}\,C$ and 45$^{\circ}\,C$. The engine’s power output is 950 W. Calculate the rate of heat output.    $W$

  A certain power plant puts out 550 MW of electric power. ru6kiei(eq 04v fqm 0.Estimate the heat discharged per second, assuming that the plant q(ive 0q46i0uk. erfmhas an efficiency of 38%.    $MW$

  A heat engine utilizes a heat soug9 8f/hdf/hcb53nr4woq feh; rce at 550$^{\circ}\,C$ and has an ideal (Carnot) efficiency of 28%. To increase the ideal efficiency to 35%, what must be the temperature of the heat source?    $^{\circ}\,C$

  A heat engine exhausts its*t0m t n:egksuaj8;4 m heat at 350$^{\circ}\,C$ and has a Carnot efficiency of 39%. What exhaust temperature would enable it to achieve a Carnot efficiency of 49%?    $^{\circ}\,C$

  At a steam power plant, stwwzi2 +0ss 1dyeam engines work in pairs, the output of heat from one being the approximate heat input of the second. Th +d10s2zyiws we operating temperatures of the first are 670$^{\circ}\,C$ and 440$^{\circ}\,C$, and of the second 430$^{\circ}\,C$ and 290$^{\circ}\,C$. If the heat of combustion of coal is $ 2.8\times10^{7 }\,J/kg$ at what rate must coal be burned if the plant is to put out 1100 MW of power? Assume the efficiency of the engines is 60% of the ideal (Carnot) efficiency.    $kg/s$

  The low temperature of a freezer cooling coil bqe7m4hwp6gocw 7u ta ( y+bc18 c(tv7is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer oyom ol1c .6g oarzdc44u/gy1o n-9 m;operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficiew: r e gf;wh4 17mdg41bnyzf,wnt of performance of 5.0. If the temperature in the kitchen outside the refrigef:w 4y1gezdrg, 1bwn;4m h7w frator is 29$^{\circ}\,C$, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?    $^{\circ}\,C$

  A heat pump is used to keep a ho:rz;q( w1k*r zl q1ctbuse warm at 22$^{\circ}\,C$. How much work is required of the pump to deliver 2800 J of heat into the house if the outdoor temperature is
(a) 0$^{\circ}\,C$,    $J$
(b) -15$^{\circ}\,C$ Assume ideal (Carnot) behavior.    $J$

  What volume of water at.ti0)y ex-v +vk5iafz 0$^{\circ}\,C$ can a freezer make into ice cubes in 1.0 hour, if the coefficient of performance of the cooling unit is 7.0 and the power input is 1.0 kilowatt?    $L$

  An ideal (Carnot) engine has an ezi*( :u ruyjcywhz1. ;fficiency of 35%. If it were possible to run it backward as a heat*;yzu.cu ( wj:iyr1 hz pump, what would be its coefficient of performance?   

  What is the change in entropy of 250 g ou9k8n (yktx ;p1fpyd 4f steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heated from . z(y z-hz+af5qwps,m 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in n g-5/jcnh7:9 qdqen+)i qgwaentropy of $1\,m^3$ of water at 0$^{\circ}\,C$ when it is frozen to ice at 0$^{\circ}\,C$?   $ \times10^{6 }\, J/K $

  If $1.00\,m^3$ of water at 0$^{\circ}\,C$ is frozen and cooled to -10$^{\circ}\,C$ by being in contact with a great deal of ice at -10$^{\circ}\,C$ what would be the total change in entropy of the process?   $J/K$

  A 10.0-kg box having an 0pl: tq zvg70 v1-2tyrk8duwa initial speed of $3.0m/s$ slides along a rough table and comes to rest. Estimate the total change in entropy of the universe. Assume all objects are at room temperature (293 K).   $J/K$

A falling rock has kinetic energyyiefc 89ztrp:6g vvc,hh(ukhq o*35 2 KE just before striking the ground and coming to rzoc6ck qvu29fh:ieg*h, 5ptv38h (ryest. What is the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod cond 1sj1d2pzh ,0y- naxjnj0 jnm-ucts $7.50\,cal/s$ from a heat source maintained at 240$^{\circ}\,C$ to a large body of water at 27$^{\circ}\,C$. Calculate the rate entropy increases per unit time in this process.   $\frac{J/K}{s}$

  1.0 kg of water at 3wvttko:85+ rnidpvhz;g0uo w :*rr) f* d4.ry0$^{\circ}\,C$ is mixed with 1.0 kg of water at 60$^{\circ}\,C$ in a well-insulated container. Estimate the net change in entropy of the system.    $J/K$

  A 3.8-kg piece of aluminum atx,5th-q,+9b b nc9mq hay wpo 7nu/sa( 30$^{\circ}\,C$ is placed in 1.0 kg of water in a Styrofoam container at room temperature (20$^{\circ}\,C$). Calculate the approximate net change in entropy of the system.    $J/K$

  A real heat engine working between hh9i*fm9 gxypz.kg0 4,tu lhl7 eat reservoirs at 970 K and 650 K produces 550 J of work per cycle for a heat input l4xl9gy7,m*kt ghfhz0p 9 .uiof 2200 J.
(a) Compare the efficiency of this real engine to that of an ideal (Carnot) engine.    % of ideal(Round to the nearest integer)
(b) Calculate the total entropy change of the universe per cycle of the real engine.    $J/K$
(c) Calculate the total entropy change of the universe per cycle of a Carnot engine operating between the same two temperatures.   

  Calculate the probabilities, when you throw two dice, of obtaining gm:q depk/6t/7ypjny9zyj8 ap5(2vc
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hands in order of increasing probabilittjf8j7bqkb5 (y: (a) four aces an 7jjq(58bkftb d a king; (b) six of hearts, eight of diamonds, queen of clubs, three of hearts, jack of spades; (c) two jacks, two queens, and an ace; and (d) any hand having no two equal-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and drop them on the h4f:u4v3mssusv 6)oq floor. Construct a table showing the su :s4 3fmohq 4s6vu)vnumber of microstates that correspond to each macrostate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about tv-g8zocr5i9q+c+md 40 W of electricity per square meter of surface area if directly facing the Sun. How largz+85t-cd vcqrm+g9o ie an area is required to supply the needs of a house that requires $22k\,Wh/day$ Would this fit on the roof of an average house? (Assume the Sun shines about $9h/day$)   $m^2$

  Energy may be stored for use during peak demand by pumping water to a h9;mtn syknh/k su)*o/igh reservoir when demand is lt9;)h um/ /n s*oyskknow and then releasing it to drive turbines when needed. Suppose water is pumped to a lake 135 m above the turbines at a rate of $ 1.00\times10^{ 5}kg/s$ for 10.0 h at night.
(a) How much energy (kWh) is needed to do this each night?    $\times10^{9 }W\cdot\,h$
(b) If all this energy is released during a 14-h day, at 75% efficiency, what is the average power output?    kW

  Water is stored in an artificial lake cre/qaiw )o cwejjz3kjz1, x36 l2ated by a dam (Fig. 15–27). The water depth is 45 m at thk1w aqx6o wz 2j3j3l,)eij/cz e dam, and a steady flow rate of $35m^3/s$ is maintained through hydroelectric turbines installed near the base of the dam. How much electrical power can be produced?    $ \times10^{7 }W$

  An inventor claims to have des(:u4vz qnf)2lm5 ajsp igned and built an engine that produces 1.50 MW of usable work while takifln )a52m(q4s zv:upjng in 3.00 MW of thermal energy at 425 K, and rejecting 1.50 MW of thermal energy at 215 K. Is there anything fishy about his claim? Explain.  ----待选择----yesno 

  When $ 5.30\times10^{ 4}J$ of heat is added to a gas enclosed in a cylinder fitted with a light frictionless piston maintained at atmospheric pressure, the volume is observed to increase from $1.9m^3$ to $4.1m^3$ Calculate
(a) the work done by the gas,    $ \times10^{5 }J$
(b) the change in internal energy of the gas.    $ \times10^{5 }J$
(c) Graph this process on a PV diagram.

  A 4-cylinder gasoline engine has an efficiency of 0.25 and delivers 220 J of wor bn.hui:)+ tmwdpi 6 cyv7v2 p; rdez)as/dz:.k per cycle per cylinder. When th th nvp):/eiyz a. i du;cz72:vdpd6r.)bsw+m e engine fires at 45 cycles per second,
(a) what is the work done per second?    $ \times10^{4 }J/s$
(b) What is the total heat input per second from the fuel?    $ \times10^{5 }J/s$
(c) If the energy content of gasoline is 35 MJ per liter, how long does one liter last?    s

  A “Carnot” refrigerator (the reverse of a Can4pk)0a r:kyk vg 3k1crnot engine) absorbs heat from the f kkkk cn rv04g:)yp31areezer compartment at a temperature of -17$^{\circ}\,C$ and exhausts it into the room at 25$^{\circ}\,C$.
(a) How much work must be done by the refrigerator to change 0.50 kg of water at 25$^{\circ}\,C$ into ice at -17$^{\circ}\,C$    $ \times10^{4 }J$
(b) If the compressor output is 210 W, what minimum time is needed to accomplish this?    s

  It has been suggested that a heat engine could be developezy g/1y djq r :t+g8x.37xooxpd that made use of the temperx138dxo y+ rpygg ox.t 7j:zq/ature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars areelr:r.e.wnau ms,e j75n: gj8uh5on 0 traveling in opposite directions when they collide and are brought to rest. Estimate the chang l jmn wu 8j70e 5::h5anoeenur,g.r.se in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cz9/iodo-7lvra vy- r x ( wqckt5zg:*:up at 15$^{\circ}\,C$ is filled with 140 g of water at 50$^{\circ}\,C$. After a few minutes, equilibrium is reached.
(a) Determine the final temperature,    $^{\circ}\,C$
(b) estimate the total change in entropy.    $J/K$

  (a) What is the coefficient of performance of an ideal h dj6 vpm1z7jmcz/31i7us5 zza eat pump that extracts hea pmsj7z/umcj65z17aiz v3 z 1dt from 6$^{\circ}\,C$ air outside and deposits heat inside your house at 24$^{\circ}\,C$?   
(b) If this heat pump operates on 1200 W of electrical power, what is the maximum heat it can deliver into your house each hour?    $ \times10^{ 7}J$

  The burning of gasoline 9 jirvdr8j5aju4 sm,2in a car releases about $ 3.0\times10^{ 4}kcal/gal$ If a car averages $41km/gal$ when driving $90km/h$ which requires 25 hp, what is the efficiency of the engine under those conditions?    %

  A Carnot engine has a lower operating temperaz gmko,lh;8 3wture $T_L\,=\,20^{\circ}\,C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal a;bt1xd izn7c+5v7 o vgas in going from state A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) Az 7tixvaod1b7 ncv+5 ;BC, and (c) AC directly.

  A 33% efficient power pla /ollvdv(r7,d7arfl ton+/ j/nt puts out 850 MW of electrical power. Cooling towers are used to take away the exhaust hea7vt7ln/d/(r a rdl /l+vofo ,jt.
(a) If the air temperature is allowed to rise 7.0 $C^{\circ}\,$, estimate what volume of air $(LM^3)$ is heated per day. Will the local climate be heated significantly? $\approx$   $km^3/day$(Round to the nearest integer)
(b) If the heated air were to form a layer 200 m thick, estimate how large an area it would cover for 24 h of operation. Assume the air has density $1.2kg/m^3$ and that its specific heat is about $1.0KJ/kg\cdot\,C$ at constant pressure.    $km^2$

  Suppose a power plant delivers energy at 980 MW using steaf f;nifrelw v9q.3fob*t860f8 oeg7 km turbines. The steam goes into the turbines superf8fbw*v0e g7e.ol3t 9 n8i;6fo qrfkfheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine.
(a) If the river flow rate is $37m^3/s$ estimate the average temperature increase of the river water immediately downstream from the power plant.    $C^{\circ} $
(b) What is the entropy increase per kilogram of the downstream river water in $J/kg \cdot\,K?$    $J/kg\cdot\,K$

  A 100-hp car engine operates at abopv2 1lp: dom8put 15% efficiency. Assume the engine’s water tep:l1o2 8v pdmpmperature of 85$^{\circ}\,C$ is its cold-temperature (exhaust) reservoir and 495$^{\circ}\,C$ is its thermal “intake” temperature (the temperature of the exploding gas–air mixture).
(a) What is the ratio of its efficiency relative to its maximum possible (Carnot) efficiency?    %
(b) Estimate how much power (in watts) goes into moving the car, and how much heat, in joules and in kcal, is exhausted to the air in 1.0 h.P =    W $Q_L$ =    $ \times10^{ 9}J$ $Q_L$ =    $ \times10^{5 }kcal$

  An ideal gas is placed in a tall cylindrical jar of cross-sec ojlxu:d4lzqag mk tgb )8689mi6r.m,tional area $0.800m^2$ A frictionless 0.10-kg movable piston is placed vertically into the jar such that the piston’s weight is supported by the gas pressure in the jar. When the gas is heated (at constant pressure) from 25$^{\circ}\,C$ to 55$^{\circ}\,C$, the piston rises 1.0 cm. How much heat was required for this process? Assume atmospheric pressure outside.    $J$

  Metabolizing 1.0 kg ouz.qr 6p7 jve+f fat results in about $ 3.7\times10^{7 }J$ of internal energy in the body.
(a) In one day, how much fat does the body burn to maintain the body temperature of a person staying in bed and metabolizing at an average rate of 95 W? $\approx$ =    $kg/d$(retain two decimal places)
(b) How long would it take to burn 1.0-kg of fat this way assuming there is no food intake?    d

  An ideal air conditioner keeps the temperature inside a(,8py c( rykb8ymswzrk9 ;7na room at 21$^{\circ}\,C$ when the outside temperature is 32$^{\circ}\,C$. If 5.3 kW of power enters a room through the windows in the form of direct radiation from the Sun, how much electrical power would be saved if the windows were shaded so that the amount of radiation were reduced to 500 W?    W

  A dehumidifier is essentially a “refrigerator with an open door.” Tlm0 sgo*fejo q h0+p1fa99 s7ehe humid air is pulled in by a fan and guided to a cold coil, where the temperature is less than the dew point, and some of the air’s water condenses. After this water is extracted, the air is warmed back to its original temperature and sent into the room. In a well-designed dehumidifier, the heat is exchanged between the incoming and o* e0p qahm9foo107+es9sfl gj utgoing air. This way the heat that is removed by the refrigerator coil mostly comes from the condensation of water vapor to liquid. Estimate how much water is removed in 1.0 h by an ideal dehumidifier, if the temperature of the room is 25$^{\circ}\,C$, the water condenses at 8$^{\circ}\,C$, and the dehumidifier does work at the rate of 600 W of electrical power.    kg