What happens to the internal energy of water vapor in the air that condenpvur 3z8 a*wx),rewqnq6b 3q ho;*:obses on the outside of a cold glass of water? Is work done or heat qn;8x6 b)z qrp ,w*3wqe*:uvorboh a3exchanged? Explain.

Use the conservation of energy to explain why the temperature of a+b+zf .teui/ 8tybl ub:6zhy8 gas increases when it is quickly compressed — say, by pushing dzz+8fb6e.tly bthub u +y8 i/:own on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is cw ffq9waxz3)5 ,rk7i done by an ideal gas. Is this enough information a3xw7qf w,fk 9ic) rz5to tell how much heat has been added to the system? If so, how much?

Is it possible for the temperatureregc41p .5fz 9+iyfrt of a system to remain constant even though heat flows into or out of it? If r 1c9gf.iy4ptefz+5r so, give one or two examples.

Explain why the temperature of y6v4k +ae0 .ixfh -urca gas increases when it is adiabatically compressedeh64uxari0 ycv f k.-+.

Can mechanical energy ever be transformed completely sh 8r5 gble3 i,*4tgiyinto heat or internal energy? Can the reverse happen? In each case, if your answer isr35gi*ylt, h4egb8is no, explain why not; if yes, give one or two examples.

Can you warm a kitchene8 s.c *zl:z +xuud9qh in winter by leaving the oven door open? Can you cool the kitchen on a hot summer dx uzh:u ce9zqd l*+.s8ay by leaving the refrigerator door open? Explain.

Would a definition of heat engine efficie6hyj556:frxu5v ch gp 2.thmvncy as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temper+7qcp1 ux:wkr+y ene-ature areas in (a) an internal combustiocn7+ xuqp-rw:+y1kee n engine, and (b) a steam engine?

Which will give the greater improvement in the efhke89*)8ac i5caei c 4tkvah *ficiency of a Carnot engine, a 1a 4ak5 98h *v)ck ee*ahctic8i0 $C^{\circ}\,$ 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 thermall u2zb; dpk;x7 (internal) energy. Why, in general, is it not possible to put this energy to uzl ;u7;2bp xdkseful work?

A gas is allowed to expand (a) adiabatically and ( bldqsw(do7/ a4i oa-zw7.bu160d5ix kw4 tewb) isothermally. In each process, does the entropy inu d /-qwsw0 t6b.d 15zba 4 wdx(o4keli7iw7aocrease, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabatically or isothe) lanxa32* zqw2cmk*jrmally. 3lcajmz q *2x) wan*k2Which process would result in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of ftbot 5fr;clhjy5n3i+xa5/ ) naturally occurring processes in which order goes to disorder. Discucin)t +hof ya; bxflj355r/t5 ss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 ku9q;mlif0a2p; ms3dc j8 rs- lg of liquid iron? Whyslf8j3 m udp29q a;sr;ci0 m-l?

(a) What happens if you remove the lid of a bottle containing chlorine 0dom8a mb*e 3hgas? (b) Does the reverse process ever happen? Why or w*he3mao0 8db mhy not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-room air conditiou4re4 dd9+ k)gb0z2m zb uenl.ner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. Whe4mb+)kb04nurd2lg d z.ueez 9n 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 room?

Think up several processes (vycjt ;l t:f5.6u.xkmother than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violate the second lawvlm:5ttc;kuf .6xj. y .

Suppose a lot of papers are strewn as3io9n0o wy5yll over the floor; then you stack them neatly. Does this violate the second law of thermodynyos0 93ow5yi namics? Explain.

The first law of thermodyn2/gb)gvf 5xfg amics is sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explainx2f/)5ggfbv g how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it tells us in which direction njh9 ; x 8zdzruzqirrhs(5k38 6x yjm-mobz* /+atural processes occur. If a movie were run backward, name some processes thatz drqhs /88* x 3mxu5-h byjkzmi;rozzr+( 9j6 you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simple food molecules inte 1 mlb+vfyj+;1qd 9p pxx;q6mo a complex structure. jpl mevd;6 qf+1m9+xbx1yqp; Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performi-2kr gx7r-d;ok/s jhp ng $ 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 frictionles9;,: s9f:fqqcdd be,k w.sr8 o(i;ps9jbkb kxs piston and maintained at atmospheric pressure. When 1400 kcal osf:b sosidkk;89: qkjbf xd9pb,rq;9 .w(ec ,f 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 halved, 9:pvhmc(x,p q:g3 iaband then it is allowed to expand isothermallyb:9h ,ip g:p 3vq(xmac back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following procd/tr9 j1ilo abuo4b 48drbew ;p/hr ,/ess: 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 pressure is increased at constant volume until the original pressure is rh,e9 / ba;ru iw8jd4rlb/ 4opbt/or1deached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pr:p,dt 9z jd+rsessure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, and lastly is brought back to its original pressure by heating at constant volume. Draw the process on a PV diagram, including num:t+ sdr pj9z,dbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, wgx0oib(ur*)s 9l.8n m qu2hrxhile being kept in a container with rigid walls. In the process, 265 kJ of hea9 xxm2qnlr hr(u u08g.io)sb*t 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 adiabatically to half its 75ums3o,2h8g xov ekxskj g7:*y6hkh volume. In doing so, 1850 J of whv eox65k,mjkk7ghs:o 7yx * gs38h u2ork 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 mL3txaciy4z f (p c-q+hv5 evwlzo.p; ), to 660 mL. Heat then flows out of the gas at constant volume,;lvxi(wqzpzyc p e4 -voc+,.fa3) t5h 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 mol/j kh;y9jn.z0)yj nmeyyw:nup5 j3 l/es of an ideal monatomic gas expand adiabatically, performing 7500 J of 5jny3;j/9n)myj.yu e:0/ pnzjw ylh kwork in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat :8 cqd0q+wwyues) 9wlis allowed 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 temperature reaches its original value. See Fig. 15–22. cqywwe9 :s q)lwd 8+u0Calculate
(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 pp e 5xaha.ed42h foxv1iw9 7)fossible states of a system containing 1.35 moles of a monatomic ide 4iv fxd1 x.2 aa59fpw)hho7eeal gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to c along the czxfm 5zaa:,tjre, 5 p.urved path in Fig. 15–24, the work done by the gas is ,zf55,xjte .m pr aaz:$W\,=\,-35\,J$ and the heat added to the gas is $Q\,=\,-63\,J$ Along path abc, the work done is $W\,=\,-48\,J$
(a) What is Q for path abc?    $J$
(b) If $P_c\,=\,\frac{1}{2}P_b$ what is W for path cda?    $J$
(c) What is Q for path cda?    $J$
(d) What is $U_a-U_c$?    $J$
(e) If $U_d-U_c\,=\,5J$ what is Q for path da?    $J$

  In the process of taking a gas from state a to state c along the curvedjvv) +.r1izeb path shown in Fig. 15–24, 80 J of heat leaves the +.bj1 )vvize rsystem 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 if instead of worki)h giv/ ids/7png 11.0 h she took a noontime break and ran for 1.0 h? i h /s/gd)7ipv   $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person wh(koj19 qb:mbz3gbcqm x k5*lx n3c4*ao sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches televisionx15obmkm(cqb 3*nlx q9c z*: akj4b g3 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 pyu/0qc f)m. eder day, using the time for light ac mq/ey) fc0du.tivity. 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 8200 J of heat while performc; e7qx8jt exj::g1 4)kkcnfn ing 3200 J of useful work. What is the efficienfx:cexcnj7 8tkkg :j4q1 ;e)ncy of this engine?    %

  A heat engine does 9200 J of witpu;p)vls3ek 01 l8 work per cycle while absorbing 22.0 kcal of heat from a high-temperature rswt8uevl)1;3l0 ipp k eservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engin7zvx+zq b3si:8 .hxhae whose operating temperatures are 5.h h7i83xq+ zb vaxzs:80$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature )*l6 l l3iccgnof 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% of its maximum theoret-mq t4nz*0jdz ical (Carnot) efficiencjm4 t zdz0*n-qy 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 hot environment be hotter than ambijo/g :mb4vn:m9 aq 6otent 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 9 qt /4:n6vbo o:gmajmroom temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at o* ,uzol1rbd5l*7 sbrthe rate of 440 kW while using 680 kcal of heat per lrs1d* l ooz br*,b5u7second. 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 argd/it4v w:h n if4yf/hn kxc*1 d-1m6de 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 pum)wb3jcbkg e su3yo :p+(3l1wts out 550 MW of electric power. Estimate the heat discharged per second, assuming that the plant has m:e3jb3( ub yw) +lo13ckgpswan efficiency of 38%.    $MW$

  A heat engine utilizes a heat source at 550* )q/-l;ciu h+zk vct77*ut7jelhppl $^{\circ}\,C$ 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 ile:rhzi- t- wj36oz;qts 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 engines work zhnp+ni 3 up4l *gda0jftc181ec9s(q in pairs, the output of heat from one being the approximate heat input of the second. T3n zp1 pc0h g q4jn(1dia9t*ecl +u8sfhe 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 yqoiuhgh62-on 4x 8 6qfreezer 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-freem grg39c /8ood)sok .xzer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficienb7hfv3.s 4fnj;5dj8 qzoz r.vt of performance of 5.0. If the temperature in the kitchen outside the refrigerator is fvqfz .j s rd5;hb. 7z8jo3n4v29$^{\circ}\,C$, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?    $^{\circ}\,C$

  A heat pump is used to (*mx1x)w2 z)au5j75j codoosb lv5m zb(c ,uskeep 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 .7qurtzc i,cgq(qq, d) aj:2k at 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 37 3ujhglub.k;;ho pj+ onm3 ,uv7-bjn5%. If it were possible to run it backward as a heat pump, what would be its coefficib h o mgb-no7h;;.uk7u, 3uljvjnp+3jent of performance?   

  What is the change in entropy of 250 g of steam atj7ly 8z. cjiu2 t )-sx*tnww0x 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is o dk8gwy rc6w:un4(c48v n;csheated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entx eelgn(76 r;jropy 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 of 2 znz oj4 zz.5aary9z0$3.0m/s$ 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 kin:vm)-iy zik; hetic energy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus ev:-;iyik h)z mnvironment as a result of this collision?

  An aluminum rod conductsjadd 9f0l ru *27wtf( yxn;t,c $7.50\,cal/s$ 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 30i6 im)dd26kg w$^{\circ}\,C$ 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 aluminumsq tkcj*(pfopijxgu+u5 9- .dj,m z). 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 6u.gy i /j2*f.w y0ml50hdstuo 50 K produces 550 J of work per cycle for a heat int00w ijmf *ly.d25gu./ oysuhput 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, whenwy pg,5;mjz -r.yr3wv 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 + 4 7zee 70vsosdounwm )tio42bgs1, aorder 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 hand having no two equal-value coe1,et)0u2 gdw+ 7azoss7 i4msvb4 onards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and drop tn*c n.6 bwwce5hem on the floor. Construct a table showing the nuwb c *ew.n6nc5mber 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–;bh(i pr m 4)+yplpli(26) can produce about 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is required to sup+ pp()l;4bpiym(lihrply the needs of a house that requires $22k\,Wh/day$ Would this fit on the roof of an average house? (Assume the Sun shines about $9h/day$)   $m^2$

  Energy may be stored for use during peak demand by pumping water swyt,84jfmm3 u c/6peto 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 abov6yptje3cms w/fum8 4,e 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. 15–22php dg(:,,k xr q4ywc8;b xiu7). The water depth is 45 m at the dam, and a steadyd8,;qbp(xxc iw hyr:g 42k,up 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 produces 52p4vtuex-ez 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 anything fishy about his claim? -42 pte5zxuveExplain.  ----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 am ozd k yra yij+r;c3 h,vq,/*b)2d:npn efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles p2yrvpjy+;,kc, oh bnr:qim3 azd * )/der 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 Carnot engine) abso( xml;eyj h9- t/p-,itiq (exdrbs heat from the freezq jx-ti /l9 -tixdy;e(h,em(per compartment at a temperature of -17$^{\circ}\,C$ and exhausts it into the room at 25$^{\circ}\,C$.
(a) How much work must be done by the refrigerator to change 0.50 kg of water at 25$^{\circ}\,C$ into ice at -17$^{\circ}\,C$    $ \times10^{4 }J$
(b) If the compressor output is 210 W, what minimum time is needed to accomplish this?    s

  It has been suggested that a heat engine could cb4 7tra 2x:ktbe developed that made use of the temperature difference betx24ktr cbat :7ween water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars are traveling in opposite directions . joe6m8xhb4 kwhen they collide and are brought to rest. Estimate the change in entropy of the universe as h6o4 .kb 8xmeja result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup at 1fzn+gxumgjghj nmx-k,7 .gdf 82/n(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 loy*x6k,hliryjh( 1c2cp+ t 6of performance of an ideal heat pump that extracts heat from +p(12o cj hry6ik6cxt*,lhy l6$^{\circ}\,C$ 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/*kds wbehh y441o( rq 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 lo/1kh ege m3p ollr36:jwer 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 C in t 0, s 2 8 cu4c*rfc9gbeqil8bg0ek;nb. )gxopFig. 15–28 for each of the following processes: (a) ADC, (b) ABC 4 .slrggx2u bo08 gcp;e) b*908neqi, cbkctf, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical powe(7vead, halk q-nzc6;pe0i 1a r. Cooling towers are used to take away the exhaust -(q6 vp1nc lz0akehie;a7 a d,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 atz7 re -5y8lfhdk *hl(f 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits it8 zy 5r(he*f-dhkl lf7s unused heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine.
(a) If the river flow rate is $37m^3/s$ estimate the average temperature increase of the river water immediately downstream from the power plant.    $C^{\circ} $
(b) What is the entropy increase per kilogram of the downstream river water in $J/kg \cdot\,K?$    $J/kg\cdot\,K$

  A 100-hp car engine operates at about 15% lkd5mr: p.9ce efficiency. Assume the engine’s water temperat5r9k lcme.d :pure 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 cylinzlc+/k-ed;50 5csb s liwm3ozdrical 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 results in ab;ye9 g 6pepr)uout $ 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 tj uai 8)6x,9w dph+ nxvnw)d4ehe temperature 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 essentially a “refrigerator with anyymq mxi.9qu: p 9g/9n 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 removed in 1.0 h by an i9 9i9:/mxuqm y.ypq gndeal 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