What happens to the internal energy of water vapor in the air thas2d ;wtcj9r-k t condenses on the outside os9rkcw 2j-;d tf a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to ex qp/icrow3 ak l+77)rsplain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the tempei p+ o7 )waqlrc/k3sr7rature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by an iddu9t+q( k0oapxoy -l,zt*o 9feal gas. Is this enough information to tell how much heat has been added to the systemtdx0oo9k+ 9 alu-zqy pt,( fo*? If so, how much?

Is it possible for the temperature of a system to +i,n9en uyf8l remain constant even though heat flows into or out f 8nyl9i+eu n,of it? If so, give one or two examples.

Explain why the temperux/j2. *j 6j;k5y uyemozy 12ivya6 aaature of a gas increases when it is adiabatically compressed juma ;zoy5ixe122av* y uyyj.ajk6/6.

Can mechanical energy ever be transformed compl8 ry56x vwhif1etely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yv5rif hxwy861 es, give one or two examples.

Can you warm a kitchen in winter by leaving the c0xby r )1h.saoven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door open? Explain.rscyxb.)01a h

Would a definition of heat 8tbzi * wn0vyg h1mq(:engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-8/ kiv(e -cioltemperature and low-temperature areas in (a) an inte-li/v koc8 ei(rnal combustion engine, and (b) a steam engine?

Which will give the greater improvement in thx +rm l(o, conu:3nj7pe efficiency of a Carnot engine, a 10 lnonmp j:( u37+rx c,o$C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous gsp26bm9zgmh2 vd v1/ amount of thermal (internal) energy. Why, in general, is it not possible to put this mh2/vp 6md9g vgzbs21 energy to useful work?

A gas is allowed to expand (a) adiabatically and jup;2oby u )-9h,bo hc(b) isothermally. In each process, does the entropy increase, decrease, o ;9-o2jyb)o u ,hubcphr stay the same? Explain.

A gas can expand to twice its or twqk ; m+7+m 4*mp;bqpel)lxxiginal volume either adiabatically or isothermally. Which process would result in a greater change in entropy?+mq+xmqtmb7 l w *4kpxp;l;)e Explain.

Give three examples, other than those mentioned in this Cdm42 arw n3:3o, nv (w0tj6dsdvqso5yp kf:v (hapter, of naturally occurring processes 0 nj snapvt::v 4d6 om(o32r3d fysd,wwq5v k(in which order goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or9uw.( a9 nqp1ds)b6vq+uvfp)jog cr( 1 kg of liquid i(sc bpnw1p 9juq(.gd u)fvvq6a 9r)+oron? Why?

(a) What happens if you redw* :m3gmv die37-34efc9 pehb /ylazmove the lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or whye/yi p-4dh3 b wzc3vfm3g:7a9 l*emde not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-r pqi;me2*iupiljui .m 4kstul50zy - 8 aky-03oom 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 streli52ukii0l-sa 3ikuty e;4mqj mpp8*- uy .z0 am of cold 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 n7(c6 ggz 1v d3tk7b)*m clwiuobey the first law of thermodynamics, but, if they atm d g*ucwkcbv)i6zn7 (g1l 73ctually occurred, would violate the second law.

Suppose a lot of papers are strewn all)zzb djlly+rd.dk+15 m:y7 fq over the floor; then you stack them neatly. Does this violate the second law of therfy d + lk+zbqdjly17)r5d:zm.modynamics? Explain.

The first law of thermodynamics is sometimxi01zoy5smx6ducfl,dh /pl c j ; 2z)4es whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how these sta0/z2mpsc dyx old f,hi)xu4l ;56czj1tements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” beca2z+;h/erda la7ff upou/ulrr60;s 2s use it tells us in which direction natural processes occur. If a movie were run backward, name delfrr 2uhu ;z+0p/2sa/fl;or7u a6s some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert re4h(fwbe/8vc e0gehs .c zq6n+ latively simple food molecules into a 6.f4 8h0qe(v ezgc e wc/+hnbscomplex structure. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performing clht*vxo;b. pt.qzu *1n-rt2 jk49l l$ 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 ;dbpyjke,,4w)*e juh- n+lbolight frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the ue4 o+, k,jj ;d-ew p*bnlhyb)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 pressuhv;b xz3+ tcaq,(lgv2re until its volume is halved, and then it is allowed to expand isothermally back to its orv3; q(+a2zvbhtlg cx, iginal volume. Draw the process on a PV diagram.

Sketch a PV diagram of the followingw ik n49h;cin7l3lm+d process: 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 2.0 L, whereupon the pressur c+nwlldni9i;k h743me is increased at 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 cm m1 thzuyzp;oij0)36 uwklwo/;2i; to expand isothermally until the pressmi ;kpz61o;z3u ci2)h;wm /u tl0w oyjure 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 / *0uspzitv to+g tc0,being kept in a container with rigid walls. In the process, 265 kJ ptti s0 ,*c0v/zougt+ 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 7m(;j f4fgy urideal gas is compressed adiabatically to half its volume. In doing so, 1(j f uyfgmr47;850 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 3el4 ot 9ty/safipl7;at 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 pressure and temperature are alspe3/ a ;7oflltt4i9ylowed 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 0kd f nop-z*z*adiabatically, performing 7500 J of work in the 0* nzdp- zo*kfprocess. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to fgjk+x5i6.a :b.pfug)onyq5p ,mss( b low 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 .,ia p)+5g(gbux.ssm6j k5 f bpq:oyn 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,:gm/de ,ppkmg +9scg two possible states of a system containing 1.35 moles of a monatomic ig:gmpdmgcpk ,+s e9 /,deal 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 froz7cg(eucdz *8m a to c along the curved path in Fig. 15–24, the work done by the dec8 g(zz* uc7gas 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 usf( lfg, 2+ j)bb(hgzstate a to state c along the curved path shown in Fig. 15–24, 80 J of heat leaves t+uhzjs(blgfb2 () , fghe 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 Exam 5qv r 7ug/ 8cziuccec-3hgd8*ple 15–8 transform if instead of working 11.0 h she took a noontime break and rau-c*e8 5c c /i3v7hrzudcqgg8 n for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleepfe2x88d j(5u 3zcs.udges- sys 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h(xscz-5e8y8guedsd.2 ujf s3 , plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one ho7dje .1p3u8,+2xkc v jsjep6 6g abdadagc,f8 ur 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 fj dde7x+pb3s,86gvaaagd16 ec k2jfp ,uc .8jat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while performing 3200 J of usefjo5eq:s r ) .hk,o:v mkacpd7 k20ym3wul work. What is the efficiency of this engko2p c 5o::kd3.0vy k)hmw 7e,a jsqrmine?    %

  A heat engine does 9200 J of wo.lkz43xe 6g qrrk per cycle while absorbing 22.0 kcal of heat from a high-temperature kez34l6rq g .xreservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operatingj*(gec5r5qs/t1 n thaotf 5r) temperatures are 58gf(s5r1hnttc qjo )5/r 5 *tea0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat enfvf , vlp96 5m)vc2gc/pc2wgngine 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% of its maximum theoretical (Carnots8kvmj3/qk: n) efficiency betwee:k8 3knj vmqs/n 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 environment be hotter thany o)(v szo0;a(0zqsjl:wqh q , 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 from air at room temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)? s ql((y:)0j h,z wqzo;o0vqsa    %(Round to the nearest integer)

  A Carnot engine performs.xszddks,,n 3uh x *z, work at the rate of 440 kW while using 680 kcal of heat per s d,,xu zn.z3xs,h* skdecond. 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 operatinly ss6 -g:a1)gyt5nwovd/. ukg 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. Estim gq ;l.i7:mulyw0vu,mate the heat discharge 7q ;:.um iwlm,lyvgu0d per second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source 7kjggo*t) vpz v11 w1bat 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 exhausxq q ge992pzt:u(n)1y0 uferf ts its 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, steam /u. kt b+(oftkby c, bgj3m)j:engines work in pairs, the output of heat from one being the approximat .yf(tbk:/3bcj +,og)b u mjkte 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 frep; m68ggjb -n3rx lfse rehgh)h:+-c +ezer 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 operatesva b( x:neqhc tu,:h9f6ez whw4 *8yw; with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of pe9f/5e mijmx;erformance of 5.0. If the temperaturj5xi /m;mef 9ee in the kitchen outside 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 keep a housnh591 upp6+ ab gmv3kqe 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 syt0+unbr1w s qn6s2-0$^{\circ}\,C$ 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) engin.9m. /bkglfb/l w4ri2r v) nzde has an efficiency of 35%. If it were possible to run it backward as a heat p/ b2nzm vbldi)wr/rf 9glk. .4ump, what would be its coefficient of performance?   

  What is the change in entroczc *,u huhdg71,e.tm06thcc py 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 heatedc+s)p:rec0j gyzu4 2t from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in en5s z :w s60rcao8nkx32bi8lodtropy 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 initia ey 1;p7qkv3xlp)g9c3uu r. )e+kxza gl 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 striking the groundtfnf7+;5 * kmnfp4g8k2 lbm7jtc*z rc and coming to rest. What is the total change in entrkc* z*jnfbgr8lm 7+kp7 5mtf4tn;c 2fopy of the rock plus environment as a result of this collision?

  An aluminum rod conduzp:h fpa i;y4 h:3tqt+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 3k;a 2 *4q )3ifjybvcl:rbd g5h0$^{\circ}\,C$ 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 aluminum5x y;ln.+ulkmoay 8b( 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 working between heat reservoirs at 970 K and 65 y9sox nm ;1aj 7dx+f6kvb3y2n0 K produces 550 J of work per cycle for a heat input of 2200 J. j6+;x7x 2 3bvny1osf9yk mnad
(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 probabilities2a1cv v .1tmij+6iabw, 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 h (w/skdx o : ogo8(e9fh9ggnn5ands in order of increasing probability: (a) four aces and a king; (b) six of hearts, eight of diamonds, queen 9(e9sfngo (/x:n d5gkhgoo8 w 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 thk;lddi9-f:bhw q78 mw em on the floor. Construct a table showingd8 q bf9;w k-7iwh:lmd 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 electricity per square meterzj+ emeoil;1h mgcae, i31j)8 of surface area if directly facing the Sun. How large an a iz8)jleci+ 1g3, em1hej ao;mrea 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 7yft;y lbo) h;4,mdzpuse during peak demand by 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 turbim o thly7y;b);d4zpf,nes 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 anac(b. l5mroe7 artificial lake created by a dam (Fig. 15–27). The water depth i(cr5bl.oe m a7s 45 m at the 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 designed and rg dgyt 3tj6+5built an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.50 MW of the+ yrdtj tg65g3rmal 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 220gnhh32p hpl:1d1x8zp J of work per cycle per cylinder. When the engine fires at8xl p: np 113zhghpdh2 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 revq(as 28l tt4 fjs0n*mp ;bz8os8s:wgverse of a Carnot engine) absorbs heat from the freezw(4saslmsgq 8*0nfb2jtv:88 o t ;pszer 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 akhhggqsu18:*r+fr *ef+s z3n heat engine could be developed that made use of the temperature difference between water at the surface of g*qf3 :* r gz+fhsr+8ekhsnu1 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 are travelingee( 3c/ (rombn in opposite directions when they collide and are brought to rest. Estimate the change in entropy of the univereebom /n c(3r(se as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup;mhdc -q0/zapvg18 cpcv 2qy2 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 coeff3w3u- 0bjw, yo)xhgovicient of performance of an ideal heat pump that extracts heat from vw3 o3o )x-hguj0wby,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 gasolhiskrl6w 0fm;k j6 4 j(war6*cine in 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 operattpwub- mj46 r;c9uoe v*s1d+ting 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 stahqi)rqi-f6 , q8hrgr *te C in Fig. 15–28 fqi -,qqr6h) i8hrrf*gor each of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electr,(a;p54o-o hrx :o:(i hrkqevllj t7bical power. Cooling towers are used to take away the exhaust heat. bvjo::eoa ; (-4kplqto ixrhr57lh (,
(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 steam turbines. The 32fnjz in s8+(c8ltz+xp o g.fwd*fp ,steam goes into the turbines superheated at 625 K and deposits its unusedwjfpp3 n, fxcn.s8 +tz+*diogz8f 2 (l 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 operaeg0a u(jl; .hntes at about 15% efficiency. Assume the engine’s water temper0nuhejl a(g.;ature 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 japoyqp 4.a qzq77: cl4x 9+tobjr 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 fa0 2i e5.xu84zfdnu:lme1gn/oe / yotpt 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 inc2 3aqsxzu6i3 side 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 essentially8 j;fb7ks qf,eevjds 8 bvy5-z;8m1e c 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 t-8e ej bckfj;e;v18ss vqdmy,f 587bz his 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