What happens to the internal energy of water vapor in the adygapf -dr; mt) q/g6:ir that condenses on the outside of a;g-d tf /6qyrdp:g m)a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energyqf+o n0f0nw:l,;zz0 lpfev4q 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 when the gas +ev:p,fwfqzzqfnl n0;0 l 40oexpands.

In an isothermal process, 3700 J of work is done by an ideal gas. Is this enougf b : eujxh/5r4bae+3bh information to tell how much heat has been added to the syste /43a r5fh :+jexbbubem? If so, how much?

Is it possible for the temperature of a system to remain constant even tyw hp// 0fx26mtith3qhough he/mpw2 3 ft/th qihx60yat flows into or out of it? If so, give one or two examples.

Explain why the temperature of a gas i n 9c;v,cnrz5increases when it is adiabatically compresseizrc,;n59nv c d.

Can mechanical energy ever be transformed completely into heat or internal dce * rr/ c2a*z tw;t8v+hneg(v2ps,xenergy? d2cc8s2h;e vwrr x/pet *ta +g (zvn*,Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in wint5e 7v x9)yw)0 hwfuw8)rctehder by leaving the oven door open? Can you cool the erdwe)) h9 cu f)tywh85wx0v7kitchen on a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of heat engin lb 8da2cm3ab o-1x)h*+ k-mn1 ovmytie efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temper:n,*rayws;m x ature and low-temperature areas in (a) an internal combustio:* r,wn ysxma;n engine, and (b) a steam engine?

Which will give the greater improvement in the efficiency 1ee4a,2x, z r.h3) wtqy omnckof a Carnot engine, a 10 ck ayow13r )etq2,, m.enzx 4h$C^{\circ}\,$ 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 (internjfa45m;0w4tg3/k e bj vyf9ui ;tg mb.al) energy. Why, in general, is it not possible to put this energy to us 9gvkfg u yj.m; i a44j0e;fbt5mt/3wbeful work?

A gas is allowed to expand (a) adiabatically and (b) isothergcmh .985w srqz ;7ey y u,a7+izz9ivemally. In each process, does the entropy increase, decrease, or stay the same? Explz;m iq 7c5ysz89we9ear ,yzh+iu7gv .ain.

A gas can expand to twice tjg1z1cgtp 3 n24fot(nu 7dmw.5-bda its original volume either adiabatically or isothermally. Which process would result in a g t7bg-mgd3twn f1z4p 21j 5tona(cu d.reater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter,pa/oeh *e(t ly 7e6p)c of naturally occurring processes in which order heyt/7ppo(e6 * )leacgoes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 kglv0r)sn c+pk(v.gr 4s of liquid iron rv)lrvs4k(gp csn0+ .? Why?

(a) What happens if yo1t4w6k da3x 8t/mz)pn;yrmf gu remove the lid of a bottle containing chlorine gas? (b) Doe)g 4 1za86ynm pmf ;wrxk3/dtts the reverse process ever 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 caloabp(s bz:es :0and0 7ls 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 0:bs psd7(no :eb0 zaacold air coming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than those already mentioned) that would oj ktpo+l,kbt1+62 tm :bib+hv bey the first law of thermodynamics, but, if they actualjt,bvt16 o:+tb2kl+k+hmip b ly occurred, would violate the second law.

Suppose a lot of papers are strewn all overudv6wo ;3qy:vla xr/r))b )lp)t yj2m the floor; then you stack them neatly. Does this violate the sjm3 x)ql ;))2u6)o pyrlbdy t:rvavw /econd law of thermodynamics? Explain.

The first law of therhc x+5 uyity9wyc(s50modynamics 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+cyu9( wx5y50tsh icy statements.

Entropy is often called ouicu n8 t77r;“time’s arrow” because it tells us in which direction natural processu tcon8r7i;u 7es occur. If a movie were run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simple food molecules intoycr l1i(chhw09* n .dr a complex structure. Is this a violation of the second law of . 9d*wl h1rrcyhn0(ic thermodynamics?

  An ideal gas expands isothe28 5pkjhav xpongwcuf )z.5/h r3c9w:rmally, 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 frictionlessd5xvlx o 4m, 7;bgi 8tldc))ls. aao2k piston and maintained at atmospherkl ;8 dcaso4.x5ad lmo gv2tl7), xi)bic 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 until its volume is halve;; r02zqy mufsd, and then it is allowed to expand isothermally back t0z;yq rsm2 ;fuo its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the folti ,a19ff2 loqlowing process: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L,tf1 lqif9a,o2 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 initially at 4.2 0zhtlt i,c:k5 atm of (absolute) pressure is allowed to ex, zctitk:2h0l pand 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 labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while being kep2 4mtfeknruhjl( n-p)b5.)iit in a container with rigid walls. In the process, 265 kJ of heat left tk 4)-. 2pbni(li mn)5tjuf hrehe 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 adiabatically to half its volumeb zt,d/w - +hybr(i2ij. In doing so, 1850 J of work is don/ ibj,y- +b(wtz2hdri e 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 ip ,bx1 iu;s go0z:u8cof 3.0 atm from 400 mL to 660 mL. Heat then flows out u:1z,8igspoc0ux ;b i of the gas at constant volume, and the pressure 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 adiaq*h b9z, 2elktbatically, performing 7500 J of work in the process. What is the chang *lq9zbtk,he2e in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to flowi-nwdhslxp 1 gc h11:n0x)bk9mzrp )6 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 temperature reaches its original value. See Fig. 15–21kdh 1:0lxx)ibn cp)r 9shpw6n z-1mg2. 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 possiblt)bg 485ttnq6ug8np/4 gfsw ejwac-;e states of a system containing 1.35 moles ouang;b 6/qwt)- jtpwn5c8g4 gest48f f 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 fhu.sowbfo fwx;0a *+6 rom a to c along the curved path in Fig. 15–24, the work done by the .*bf fua+s h;oox06ww 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 gas fr nj/yn sb,9inn443 yzgom state a to state c along the curved path shown in Fig. 15–24,,34i9n /g4 yz snbnnyj 80 J 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 m3)nqn6at(c 7o pdv6b if instead of working 11.0 h she took a noontime break and bq 7om( 6 tp)nc3dv6anran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, 0w4s+m* zo-m mpoazz9 1jn7 dzsits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 o*9 z+j-zm 10nsdw mpozam 4z7h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per day,fcaq5pokw 9e1pqbl j;8 c,x2 ) using the time for light activity. How much weight (or mass) can this person expect to lose inwxq8p5 k o2;,fca1jl ) 9qbpec 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 8200 J )5jgpuc 6 le +;)cooldof heat while performing 3200 J of useful work. What is jo +g l;l)p cd5)u6eocthe efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle whili b ibyq( vq3s:l9q1x(q1hx.i e absorbing 22.0 kcal of heat from a hix9li1y.( iqvi q qbxb3q:sh( 1gh-temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose oiwx-v7 7 wmr:syq.hh0v ulk21perating temperatures are 58rsilhxqm-.v27w 1hkw0: v 7yu0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperaturej; b k+ysoeb /)h8p2re of 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 at 75% oz h9tdk8o(5 m+0owywx f its maximum theoretical (Carnot) efficiency between temperatures of5 +x8d(twkohy09 ozm w 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 envirjbpw ), mprb-*onment 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 fromrpb,p mw*)-jb 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 440 kW dtprgdkd0.t;k.v7h2 :sr 2et while using 680 kcal of heat per rdte k0g . ht 7tkprdsd;22.:vsecond. 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 temperatures are 210 h ak0p2txy t4t+a+3ge$^{\circ}\,C$ 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 ou 7pfj5irs3 (jagp/4xf electric power. Estimate the heat dischargedjpi3agfu 45px s(/rj7 per second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat sourc+wh e656ktd zy12vj rd2ciyf)e 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 heatkl+9db izg3i. 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, steam engines work in pairs, the output of heat from0) xknho2n0b 0hdyjz2 te0y0a one be zy0enk20b0d )a0 hjxyn t0o2hing the approximate 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 cooling coil is -p-uv(epvg 5ueakutxc(e6(ktr );z79 15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operatesfn zxd*be0t , g8vmjof,c4ztj h:c59- with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5.0. *:7hafqrzg69dscep7 If the temperature in the kitchen outside the 77r *s d9z6 cagq:hpefrefrigerator 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 housl cm2m9(px5 x3 c(.swizr iti,e 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 (0x117y 3wwvyxq + 20viuc5d nnfuoo o0$^{\circ}\,C$ 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 , e*5 kgwbs; q0sayk6swere possible to run it backward as a heat pump, what wou,s*qkay0;ewk g5 s6 sbld be its coefficient of performance?   

  What is the change in entropy nzq )84ib-g un .s.eyyof 250 g of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water)b) .rp5mmls1sw ,xc ,bkcq4 r is heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy o qx3fv3g- ;tukf $1\,m^3$ 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 rtnj*lbva7 ktr f; ae:x 5 -8zah:l/y,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 l:q2p,0a brl-/l: 8zo4f bb gxr fu9zcbefore striking the ground and coming to rest. What is the total change in entropy of the roa 0/fzq2b r8-fcu:l4: g 9zrxpllob,bck plus environment as a result of this collision?

  An aluminum rod conductqi64ndg e:a 3as $7.50\,cal/s$ 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 3m ihgvq( iy-35*rw3 jd0$^{\circ}\,C$ 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 alumxp * 5*tnsab;gayhz4j *ry2/jinum at 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 workingvdk.dkhv9w1z*3a)rcpk4r shn; qs+ / between heat reservoirs at 970 K and 650 K produces 550 J of work per cycle kv9zd; /rh1+d q)wvsrha . kpksc *n34for 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 probabi7 )oc v7uw8kpqcsv 6q/lities, when you throw two dice, of obtaining
(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 oxwz/o2j*,wq s7cj1nz f increasing probability: (a) four aces and a king; (b) six of hearts, eight of diamonds, queen of clubs, three of hearts, jack of spo12z,n xc jwsz q7w/j*ades; (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 k)uo *dnullj.tbg0yb; vo6.6coins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspondobnovky6;gl0tuj).*bd u6 .l 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 produurux 3)eioo78lp +:u ace about 40 W of electricity per square meter of surfap37uuxi)+8 o :areluo ce area if directly facing the Sun. How large 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 pea)u)cjg0 1t1x1euhd sg6wq.o ak demand by pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Supp u).o)jwdg sugeq0 htca611x1ose 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. 1dzp 5q*fb 1+t7yfee 9l5–27). The water depth is 45 m at the dam, and a ste 9t57b 1lfqd+e*ypzefady 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 enginb(q1fyy04/qr qd. ckdfwt1 3te that produces 1.50 MW of usc dq 4(q0b3 1q wr1tfk.ft/ydyable 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 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 hajkmzu0p 7jd ;bm 3.8p9 xelkg4s an efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cpmu7zbgjke04 jk 9ml;d x.p83ycles 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 6kz (x0 zst+w)mx1t 9/qxho rks:ml.i(the reverse of a Carnot engine) absorbs heat from the freezer compartment at a temperature of zotk(16q w)hr m 0 xk:sz9 +x/ist.lxm-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 hesay5 cm,m7q zn90xo)yvs1*nm at engine 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 trop 7q*s zy nomc50vma,)y1 ms9nxics, 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 are traveling in opposite direnxt jf)vv85m* ctions when they collide and are brought to rest. Estimate the change in entropy of the universe as a result of this colx * njvt8f5)mvlision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum jpg h- ep*+tgie tw) ,g*zv*u0cup 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 /+-zv ,csnosi 3ur c+yheat pump that extracts heat from 6zy+crsn-/ cusv+o 3,i$^{\circ}\,C$ 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 releases abjb mt7vgm r:+0out $ 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 a2s wm1 wlkh3b2 lower 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 from state A to state ml b(hqmom jl n1;- txm:/y (l-ixqg2-C in Fig. 15–28 fmxxm2l;lbjl(ym-n /m:g o 1itq- qh( -or each of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puty,h b77h0.i2s okc3d4z ccu,k :lq*bv fred b)s out 850 MW of electrical power. Cooling towers ar2ko,4 0svf 37ri):cq.bucdlk bz7 hhd*yebc ,e used to take 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 delivers ent dj vl,xyop2,;uhp, 7ergy 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. Assume that the turbine operates as an ideal Carnot engi l ,yj;opht2vd,u 7xp,ne.
(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 about 15% efficieb/ zi+ +bar8istx4pp ,ncy. Assume the engine’s water temperature rsbxa 8+4 b+,t/ipip zof 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 tarvs v ffod dd+-..l(2mll 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 fat reswwg.v,h0 opa) 4nigb :ults 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 ip ;(qk+z 1hucmnside 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 essentially a “refrigerator with 7ase8 f5.,hbw tv m yfz.z;s:h3ba 9wuan open door.” The humid air is pulled in by a fan atwz8zuaa3h .9v,f;e:msh b7.w5ybf s nd 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