What happens to the internalkhwtc):p6 r7e energy of water vapor in the air that condenses on the outside of a cold glass of water? Is work done or hea e p)rw6hckt:7t exchanged? Explain.

Use the conservation of energy to explain why the tempe1s ve.eqd((:uqf.h9m n qcu: rrature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases when the g.(ve (:es:qq .qn9 fmhd1ucuras expands.

In an isothermal process, 3700 J of work is don+l5t 8, xldpbbe by an ideal gas. Is this enough i,xdplbt8l +b5nformation to tell how much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system to remain coq :r awr,b;*p x0 g7kjqdrq8+qh )9knonstant even though heat flows into or out of it? If so, girb8+ rd,jg*kq: rhw qx; q)097oq pankve one or two examples.

Explain why the temperature of a gas increases when it is ka7*y qtddpzcu3p7 1u,kndq .l2w:w2 adiabatically compressedd *cy2z p:l,k7q7t3.d2unqwa1ukdwp.

Can mechanical energy ever be transformed completely into hnt2+sd(a 0qwh9 ja d,oeat or internal energy? Can the reverse happen? In each case, if your answer is no, exhn jaoa,d(+209qdwst plain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven doo 1 8iq 27p(:,ogs.c tsccawvyir open? Can you cool the kitchen on a hot summer d ap cvgt:s8cc,17i(2wy q.soi ay by leaving the refrigerator door open? Explain.

Would a definition of heat engine efsv/m ;,lf jul-kh ;l+vficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and l 9bmkpbo*3fmhi/cfq5i44s8v ow-temperature areas in (a) an internal combustion engine, and (b) a stea f b/vbo594 ik 3i8pshmcqf*m4m engine?

Which will give the greater improvement in the effd *s0abqy k,i6vv 5b1ciciency of a Carnot engine, a i y01sb5adv6bqck ,*v 10 $C^{\circ}\,$ 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 (interm5vb 0,2toe qgefl)rf 2wsw(-nal) energy. Why, in generavl0()bsw , fewgermoq -f22t5l, is it not possible to put this energy to useful work?

A gas is allowed to expand (a) adiabatically andc3wnd)a,9atf5 :m qd88iz gzw (b) isothermally. In each process, does the entropy increase, decrease, or stay the same? Exwq8),8 9 zmi wacf5 daz3dt:gnplain.

A gas can expand to twice its original volume either adiabatically or isothsxe )jgutp(gs +8i -4oermally. Which process ios4p 8( xe)gsguj +-twould result in a greater change in entropy? Explain.

Give three examples, other3es4vt-wz4/an1da y74 txvt/gf e jj, than those mentioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the obswvy47sz-e a 4f ttagvx4/t3d ,/jenj1 ervability of the reverse process.

Which do you think has the greater entropy, 1 jn . 3vmy6w-xykg of solid iron or 1 kg of liquid iron? W-3jyx.ny mv6w hy?

(a) What happens if you remove 4d7e h; n4osk/gt)i pad56ubrthe lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you the u4 /naih7t6op g5s;)kr 4ddbink of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-room air con 3niffqdm /;m)b-c2 ueditioner”: 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 coming out of it. How do you know that this machine cannot cool the rub dc3 qmf2n/ei ;m-f)oom?

Think up several processes (other than those already-e; /vjg6edl q mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violate the sec/ - dev6egl;jqond law.

Suppose a lot of papers t(spyf8+3 :hg)ko tpani iv/0 are strewn all over the floor; then you stack them neatly. Does this ( vapysftk +/ i0pn3go:8)tihviolate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes ;g wy- wmgx-+awhimsically stated as, “You can’t get something for nothi+wg-myxa w g;-ng,” and the second law as, “You can’t even break even.” Explain how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because oyq7oocju po+v9 ,*v6 oem x-4it tells us in which direction natural processes occur. If a moviev46 oojqeo7 9o*c+m- vu,pyxo were run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they gry5nd in2j.704i btufj ysgdzs2 /a: :fow, convert relatively simple food molecules into a comple s/yd .jsia4:dt :bn ugfz52j2y07 finx structure. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, perfor8e srw*- woj8qming $ 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 frictio2;xo2nfqk q/,hswdh + nless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is observed to increase hh; q,2/dnsqx2+k ow fslowly 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 unb b9+huzxxp7.i(ui x,e1qpn 4til its volume is halved, and then it is alli,zu4x pbhe9x .(pnqb1 u7i+x owed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas at atmospherwcsykg/3 ) ay 08l*tqhic pressure are cooled at constant pressure to a volume of 1q/htws0 8y3 )l*ycgak.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the original pressure is reached.

A 1.0-L volume of air e,uyne)s1i, ho t,f frpa.v5,initially 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 pressuree )u. o,t,ysrna ,e pv5f1f,ih by heating at constant volume. Draw the process on a PV diagram, including numbers and labels for the axes.

  The pressure in an idj4f lm,mi 8ptkj v2vwf3w05g/eal gas is cut in half slowly, while being kept in a container with rigid walls. In the process,2if w,kwjm3v54 tf g0l8jp/vm 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 is compressed adia ./ fuuyw;c;ft2j 7dre9sg7h gbatically to half its volume. In doing so, 1850 J ofr2f uh/egsu wtj97df;;y cg.7 work is done 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 ab ic 55szduko-b1+8p wt a constant total pressure of 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressuzkd1obc- 5s 5 bw8p+iure and temperature are allowed to drop until the temperature reaches its original value. Calculate
(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 expand as,.pia+z9z aj diabatically, performing 7500 J of work in the process. What is the change inz ,i+.9ajzpas temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed,ph+x u x/4boi to flow out of an ideal gas at constant volume 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 temperoxhxp4u+i b ,/ature 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 y o)xun2zfxc8 z*.k u.possible states of a system containing 1.35 moles of a monatyncz*2).8 x z uku.xfoomic ideal 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 frwfp6i*/j5r pd om a to c along the curved path in Fig. 15–24, the work done br*p5/fi6j w dpy the gas 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 gdc0 qnv- j7p,iulaf 6h:h)z;vas from state a to state c along the curved path shown in Fig. 15–24, 80 J of heat leaves the system and 55 J oz7f lph)- ,a6ui:vdjnh;v0q cf 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 transformc pwb:il0vnsb4k3r-. if instead of working 11.0 h she took a noo.3vsp:r 4ciwk0l bb -nntime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sits at a des)2a5n kptif6mk 8.0 h, en 5a6kimtn) fp2gages in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per day, using t ,njp /udgh d2w6 sm1vmdm-rw5x-ae.vdac/*0he time for ligv1wm25r.w- m vaex/- /dd *,chdnsmp0uj6d aght 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 about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200q:;t*iow8d2a:d xiw4od-i v1d+hl ym J of heat while performing 3200 J of useful work. What is the efficiency of this enginxol oq2iddy8h:wvmt* i+i;:wdd -4a1 e?    %

  A heat engine does 9200 J of work perj xiwwfly, 71n1 *b9ai cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the efficiency of thil 9x1y17 wianb,fwji*s engine?    %

  What is the maximum efficiency of a heat engine ; (,8f(phvaelz8+ ubului1b n whose operating temperatures are 5(1 ,8n8e favbiulz(;lp+ h ubu80$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature oyo ;n9dst-bb- /v, ab( rqsk ;i(pfd6of a heat engine is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operates abcog 3.b,i9dcso h o:8h*t sb2t 75% of its maximum theoretical (Carnot) efficienc98.bgbsb osd ,h ch23* tiooc:y between 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 ,/xnh sn2xoa9 hot environment be hotter than ambient temperature. Liquid nitrogen (77 K) is an,o9 nas2/ xxhbout as cheap as bottled water. What would be the efficiency of an engine that made use of heat transferred from air at room temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 44 .woz2gv 9njb:x 5n(ac0 kW while using 680 kcal of heat p 5 9(nzbgv.:aconjx2wer 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 operating temmg qr((7 o;zilperatures 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. Estimate the he .onuwvbv:h(fsw*l)u:b:z, 0g5au k yat discharged) :wbuv,fvzwl: una*bg0:s5uy( .okh per second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a h. :q d -zmq oq44c-purvetgi621 dkg-veat source 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 heat at 350kwvp*x32 ihd 2pmeoyhu8/32ye bjo.;4ic:w e$^{\circ}\,C$ 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, steam engines work in pairs, theqj-h91ak a +uek/tn f9rse 1)j output of heat from one being the approximate heat input of the second. The operating temperatures of the firs tef+j ua1)rs9h 1neajk k9q-/t 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 free -krvz+sr c6 )mb;6tvc:ynu v e.d v9j1r/g5ovzer cooling coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates with a in u fiqb3-xcqk(2 7;scy/ bclu5a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficienude irvo1asq+9a2lk(4cee58zg *0c wt of performance of 5.0. If the temperature in the kitchen outside the refrigv ire 8u4ce1o(2age5k0+ q*9slwza dcerator 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)9xeo n *m*dod s.ty) c1epx8d6tqii: house 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 mw9x5* ir6uziy1,cw f0$^{\circ}\,C$ 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 efficiency of 35%. If itpjb-vb 1qdta0b3 o6:ajy(9e y were possible to run it backward as a heat pump, what wobbvy(ej9qadpa-bjty3601 :o uld be its coefficient of performance?   

  What is the change in entropy of 250 g of steam/d(dto-gy kq 49nof: a at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water ib,xk c(g1xgi).yk m)f s heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in u bk95oac5w+5x 7aaxr entropy 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 aja6m;wtqwi)--r1 d(nk n:mht fh+ vl0n 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 energy KE just before rmb,scs7;.g6kr8a5j9u evwn striking the ground and coming to rest. What is t9msje;8w an.kg,r usb65c7r v he total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod condum6 1(j kh;gvhhiv15g+gqn/e oe(ii:r cts $7.50\,cal/s$ 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 30v .r8/ o 8s01uymwqnv mdsf4j($^{\circ}\,C$ 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 at vs sq505wyqo530$^{\circ}\,C$ 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 wxz,xw l)kd1me;5r ng- zkw e-wj,3 j)morking between heat reservoirs at 970 K and 650 K produces 550 J of work per cycle for a heat input owmmje 3-wxgzw,kd x,;rkj-5)e)n1l z f 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 obtaining4dz (g1d; * )ffbfmmul
(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 increa08 x,w4 lf/svthats/lsing probability: (a) four aces and a king; (b) six of heart8xt4tslh vs / waf0/l,s, 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 cz-xxv1k5y ,c hoins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probz5kxxh- vy c1,ability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produc;eqqhkm ty1;03wr;mkr; i 9ag e about 40 W of electricity per square meter of surface area if directly facing the Sun. How largk mm;hk3t9ge y1rar; qq; wi;0e 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 puanv(v s;v54ammping water to a high reservoir when demand is low and then releasing it to drive turbines when ;a v(namv5s4vneeded. 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 created by a dam (Fig. 15–27). The3/ *zgbz ;stu l9,etds water depth is 45 m at the dam, z/9z; u*3sse ,ltgtdb 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 designed and built an engine that pyrnrjgfpja; dc)r 9p:bd1 2gk.(ly1 ri6 f ;(wroduces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.50 MW of thermal energy at 215 K. Is there anytrpk ( 9gg y(cd.)r ir y n1bd2jpf61:r;fwlaj;hing 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 effican. bl(5pqzy;jtidd4 a-a) (l iency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 (y-j54ta dlndl;pq (ba) iaz.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 Carna3 +y3qhmpanf ;xm 39)kb s-unot engine) absorbs heat from the freezer compartment at a temp 3b 3qf;a)k3nns-9m huym+a xperature 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 devenb,u:dj)i9sjb z 1(7lah3 b zqloped that made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures m3j di7a 9jbzzq hb:ln()s b,1uay 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 are travg;as n t4aw1kk55tq 8weling in opposite directions when they collide and are brought to rest.twtak18 s g an54qk5;w Estimate the change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated alu*t cn51s6 lhasg2/xb 8ax cxx-minum cup 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 heat p4tg6iqh7czdp+mug o: 7dl 8ne,6c kw.ump that extracts heat frc6p,+dci4lze8 m. dngt 7 q76h :kwougom 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 in a ca0n*uo,h f8w0akudwyi) 3yo j22ud g-mr 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 lowe fb a)y5ohmja z8k7e76r operating temperature $T_L\,=\,20^{\circ}\,C$ 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 gas in going frow+8-x 4vj + z3wadl*qe gzezf(m state A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC directlyz4*j+(lqzed 38 xvwza - gfe+w.

  A 33% efficient power pla;;c6 prm p*d2:febn kvnt puts out 850 MW of electrical power. Cooling towers are used to t 6mp vn: kpbecfd*r;2;ake away the exhaust heat.
(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 delivet 8ghfkwcz*1 3 h;m-wul yr-1irs energy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. A1g ;fthr cu y8iml--13z*hw kwssume 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 oh ngtexj, xjws3wl(3 dz8ck3n x5b2tf/7 3m4gperates at about 15% efficiency. Assume the engine’s water temfmx7wjnjh2 3gxseb3zc 8td3(g 3wxntk ,/ 5 4lperature 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 placed1fhaj kt y+h+59zs7ux in a tall cylindrical jar of cross-sectional 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 of pl2s 9bs -4fkafw6 h1s- 9kscrfat 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 ic2us) lt.:nw bt6un: 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.” /fl,; 3le6/ ezjzpkbaThe humid air is pull/e pb/keljzz,3; l6afed 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 outgoing 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