What happens to the internal energy of water vapor in the air that coneo 54tufh .61b7q oksp 8rpjc;denses on the outside of a cold glass of water? Is work done or hea5 o1kftp ;o4bc7r6 pheq8s u.jt exchanged? Explain.

Use the conservation of nh +wr81y eyj7uwqb)1energy to explain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases 1eh jb7)r+qu1nwywy 8when the gas expands.

In an isothermal process, 370xbrvfx,l1 9,t0 J of work is done by an ideal gas. Is this enough information to tell how much heat has been added to the system? If,l v9rfxt x1b, so, how much?

Is it possible for the temperature of a system to remain constant even though he:73)gqy u, jwzixg n(;3rurz oat flows into or out of it? I:n3,;(iouuz7x z w) 3ggjryrqf so, give one or two examples.

Explain why the temperatuu;e c+,2w6 6vy+f icpkcvnj(xtr1dx6d bu+ l8 re of a gas increases when it is adiabatically compresse2dc6ufv 6bwxj;u+,6ilc1xk dn vp rty e8+ c+(d.

Can mechanical energy ever be transfalt .pp(h6( p5bj4et+x ,vtz yormed completely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one or two exampl vj6tb 5h+4tl(.p(e,pyxaz tpes.

Can you warm a kitchen in winter by leaving theit fv b*/)/pup)l9invw x2i w8 oven door open? Can you cool the kitchebu tf 9 /ipiv2wwxvip) 8/l)*nn on a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of he*ozfaq e -7+fk60j4 /xvhrgayat engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature8hkv bh/,j o0w (wb6bw1nmu(v areas in (a) an internal combustion engine, and (b) a steam enginvo801ukv j/(b,bhhbww w6 (mne?

Which will give the greater improvement inm+bl) rfyf +4u cs;w l.a/m4 d3j0tgyb the efficiency of a Carnot engine, a 1a+lg40f) d. tsb yjmm y3 lu+r/fw4c;b0 $C^{\circ}\,$ 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) rdie htw5bmj+e0kv8 z8:o 5e7 energy. Why, in general, is it re: jowkh5 bv8z0e87d e t+i5mnot possible to put this energy to useful work?

A gas is allowed to expand (a) adiabaticallyps1qdbt6t5i amgjs6 x;(ik;2 and (b) isothermally. In each process, does the entropy increase, decrease, or stay thgix ;kj 66(bs ; 1qads2mi5tpte same? Explain.

A gas can expand to twice its origmy 9qd-.3gjt iinal volume either adiabatically or isothermally. Which process would result in a greateiy.d-m9qt j g3r change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, o2p t 5ajm*y;y*nb 1sqcf naturally occurring processes in which order goes to disorder. Discuss the observability of the1y*n5s *a ;qp2y mcjtb reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 s49fjpaw)c. 6hc roq3i rhlnn2q x435kg of liquid h rrql jx)5f ic3a43 c o6nn9w.q24phsiron? Why?

(a) What happens if you remove the lid of a bottle 4we0ji ,z 2u7igic2e icontaining chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two 27 w4eeju ziiii cg2,0other examples of irreversibility?

You are asked to test a machine that thnmn e/ x vs,0ho.sunis(2wk66e inventor calls an “in-room air 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 coming out of it. How do you know that . 6 smsnu( nnx/i6okw,h20se vthis machine cannot cool the room?

Think up several processes (other than fqal)qb1 kb9,those already mentioned) that would obey the first law of the qlbq),b 1f9karmodynamics, but, if they actually occurred, would violate the second law.

Suppose a lot of papers are strewn all over the floo6)x90yk mqlykr; then you stack them neatly. Does )9ylky k0q mx6this violate the second law of thermodynamics? Explain.

The first law of thermob *mptk nb3rx);f :b4cdynamics is 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 statements could be equivalent to the formal statementsprmc b4k; *3x) fn:tbb.

Entropy is often called “time’s arrow” because it f:cien7 . d.t 4ea.r6tm;dwc utells us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that would tell you den6mr wf ..7 eut;cc.4 dita:that time was “running backward.”

Living organisms, as they grow, convert relatively simple food molecules i aygeaeze2k-(p. -*m znto a complex structure. Is this a violation of mk gea*a-e2(ezpy z-. the second law of thermodynamics?

  An ideal gas expands isothermally, performing iyqxy3noiz) m*;hx rv6pl5 -($ 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 ukq;li,vet )/8h p v4ucylinder fitted with a light frictionless piston and maintained at atmospheriv4eku /l8phvtui; q,)c pressure. When 1400 kcal 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 une6k bxu-* f( e8kwu8t kyin2u;til its volume is halved, and then it is allowed to expand isotherm2 uun8kx(6e;kywe -8f* iktubally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of fl*lza rwxsy 2/15adeb8 jt5:ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased 8 5y:lat/ *d zelw51 b2rsxajfat constant volume until the original pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is allowed g4sccl qu,k 94to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its init,9lq4u cgs4 ckial 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 labels for the axes.

  The pressure in an idegc 0b axcq+ih7 r,s1(.vpia *kal gas is cut in half slowly, while being kept in a container with rigid walls. In the process, 265 kJ of heat left h *r(p0ciai +scq.7x1, kvgabthe 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 adiabatkreoeb8(umdeb1 u:in91/ y ;r ically to half its volume. In doing sr rm dk1iu: b(ee819e;byun o/o, 1850 J of 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 at a constant total pressure of 3.0 atm from 400 mL txd-u.yqck1e hyfwd7w (f.mskyv31b .:rg /p5o 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 o: (kqf .rywv 1d .y31usemgf7xc -/byh.5kw pdriginal 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 adiabatw s,(uk1nj i6ix.e7* hbp9eubically, performing 7500 J of work in the process. What is the change in temperature of tx7s,u 1ueb jii(n k.e9 p*6bhwhe gas during this expansion?   $ K$

  Consider the following two-step process.:r4isrr 4pji:+cta8 q 5cdr5o Heat is allowed to flow out of an ideal gas at constant volume so that its pressure drops from 2 :ca pr45+ rtcs: qidjr8i5r4o.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 states 8(j p4*tzi(qtbaal8z of a system containing 1.35 moles of z(*qbi8tt4( paz al8j a monatomic 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 from admvx7rlh 4d( 6 to c along the curved path in Fig. 15–24, the work done drvd4 lxm67(h by 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 v ezvk*3w ,on;gas 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 of worv*zoe 3n,w;k vk 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 oa+c rz: 7)pfnqf Example 15–8 transform if instead of working 11.0 h she took a noontimrp)a qnz+7f :ce 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 deja20 mmef :lg) xm7ob0sk 8.0 h, engages in light oa0ej:27gm0m)bxmf lactivity 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 tp2a1w4,hoee :oid04y ru pmz:he time for light activity. How much weight (or mass) can this person expect to lose in 1 year, assuming no change in food intake? Assu ,4:o1ey4 2whdium pproa0:ezme that 1 kg of fat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of as *q;ry8ey8 whkzar+ l1()pz heat while performing 3200 J of useful work. What is the efficiency of this engine? 8za a)y(*psewyr;r 1zqh+lk8   %

  A heat engine does 9200 J of work per cycle whhh c9e b8vz7sb3an9zhq44 :kjile absorbing 22.0 kcal of heat from a high-b9h:qhjnkh3zbszc89 ave4 7 4temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temperatu5q zkljmnh20g 7i4;e 8ivok x9res arekh7m5n 4o0eg8vq 2;jzi9x lik 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat eng 0oic. u1eidw+ine is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant ope0b(swdz3 , h, iquy(hal7p)ic rates at 75% of its maximum theoretical (Carnot) efficiency((7 , 3 pydlbaq)hiws,cui 0hz 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 hehwo2t 6 ltlzjj/ l7.-wj nci +4;f7bwot environment be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap af;t/4we.t2cojl n w+whj i lbzl677j -s 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 we j8 -qi*vpve2ork at the rate of 440 kW while using 680 kcal of heat per second. If tip-* 8vvej eq2he temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatures w(/k r)p. yiekare 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 w wg8d3xpnmz,4 m.ocg)a4op s+ s;fj le0*-ww MW of electric power. Estimate the heat discharged per second, assumig ) ps owwn8;w4jo z*f03cepxlm4+- gws, m.dang that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat vny 37o-fsq6 ssource 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 a 7qk-ag ,*csqht 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, steam engines work in pairsdc (ebic;l,iselw2 q, p7 ,u+n,sdyq-, the output of heat from one being the appro,ds,y lbc-;sp c2 qud +,,w7nl(iiq eeximate heat input of the second. The 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 cooli8zc9jlo -i z7rttc l5y32-x ck/x9ph ing coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezexwq w( 9,rhg ()/,herc knxn.7vsx( qhr operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance oooe7-: m f;uv7kl:efca 06obqf 5.0. If the temperature in the kitchen ouo7 e:l :ovkfu7moef0bc-;6 a qtside the refrigerator 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 k;blgqjh.u6k8 fsem3w 8v)5 uzeep a 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 m0 h-0 ma*jk- :c0llua.tyh n91vyz awat 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 efficiency of 35%. If it were possib.tpc 0hyh; sa()tsi50g6ilu)rm z:i ale to run it backward as a hea ;sh 5 yl. mih)sug6 0crpit)aza(ti:0t pump, what would be its coefficient of performance?   

  What is the change inz nr7gw9pf m.bvw36vsm;0 fe) entropy of 250 g of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heated fr8 .rfi0gi) kk0io* hjs1r /v2s)mauuuom 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change im. a u n9s k7nvb7fj4y;9ptc(hn 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 an initial speed 9xu7qi )tp 7jl;jjr(zi56 rmyof $3.0m/s$ 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 kine(s/ dz trih2/ 1c-+b1oar5rcheo pf-itic energy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment as a result of io rr(fc /+t i2o-51/ep-z hsh1dr abcthis collision?

  An aluminum rod conduct ;hp5sa e+d*m,nnt u(os $7.50\,cal/s$ 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 30;k v8vlwn-/zpr ezi0e y 2th8/$^{\circ}\,C$ 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 atuh-kgbxp+d6nfv(-s +.06siz 4ehw gj 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 v;tb,iwk5gr;: q, :l z,diwmqbetween heat reservoirs at 970 K and 650 K produces 550 J of work per c ;5d : ,zk:v ,rigmqlwbwi,tq;ycle for a heat input of 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 st,o3+qxt gq/i 4 -hhxxa8)dxprx9q*obtaining
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following fimj-2zdr ol -;vve-card hands in order of increasing probability: (a) four aces and 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 ; --dlrvzmoj2hand having no two equal-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly5* eliw,hpaxr 4j:it / shake six coins in your hand and drop them on the flo,a5w p l:xherij4/it*or. Construct a table showing the number 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 40 W of electricijqh r2 p4g7m 8 6hvh/.lfh6gw1im)xxfty per square meter of surface area if directly facing the Sun. How large anq7vx h486hmmw/pg.rj6x 1f2f hg lih) 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 tk 22mtc.+jwz pih: (ad 3ix2mby pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumped to a lake 135 m above the turbines at a rate ax.h:k 2ct 3+dzmijp22t(mwiof $ 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 la/ogc83r 0a/ iet orn-2tls7 gjke created by a dam (Fig. 15–27). The water depth is 45 m at the da0e/ co r7l-2tog/sign8ja3 rtm, 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 burdef5 /,.t is3old +stilt an engine that produces 1.50 MW of usable work whilrtd/s3seif 5 .,+ltdoe taking 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 of5vj iary z2c82)dq;mt work per cycle per cylinder. When the enrz ;8ac5y q) jt2vmdi2gine 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 (z1 v+)ziilb7 vm.kk2 i h,wlu7the reverse of a Carnot engine) absorbs heat from the freezer compartmentuz 1lizv.k kbhw ,)lv77iim+2 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 engin.k twg+k8dc *q8 a 7xvyc2j9jbe could be developed 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 w7 jq*kgb.8akxd9j8c2 +tyvctemperatures 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 are traveling in opposite directions when they collcs fygpfy s.4 .-hg:ibh(e77 jide and are brought to rest. Estimate g. s7.bce:gj-ip (4fsf hh7yythe change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aludo))mcd;.m tc 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 pump that enu yf:5*l la61i px.kzxtracts hex6k1yi *u .a5:z fpnllat 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 in a car releasesp ry,hbn7h+ychyi. ;: 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 nax6hi4o4ss :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 from state A to state knpqmal 5 0prl m/9x5y +i2(cjC in Fig. 15–28 for each of the following prj/ka2q+li5cry( m0 pp5lmx9 nocesses: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 Moq,5ka g nv6 x/b:3jnjW of electrical power. Cooling towers are used to take away thebn3/a5:6v,gqj oxjkn 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 delivers energy 3jb 49h;gsco6s ;iekiat 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.kg;iib3;ehc6 4 j9ss o 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 aedy 4.3c zaps4bout 15% efficiency. Assume the engine’s water tempcezs3a4p d .4yerature 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 z 0z71+jc m:gstmq 90.cqzsc wjar 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;9 8u0d ta:a,fdgbb7d g7tjfs 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 temperaturg(oe7hv2ksts ( c- f6+ o+b)flzqo uy5e inside a 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 essentiallyaqov-2* djl3a a “refrigerator with an open door.” The 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 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 removvd* lj-2 qaa3oed 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