What happens to the internal energy of water vapor in the air thg.evpj*lqy0gj - 5k/dat condenses on the outside of a cold glass of water? Is work done or heat exchanged?05 q.jlvd-j g/gy k*ep Explain.

Use the conservation of energy to explain why the temperature of a gas increag:p 3khmoo1.ltb9n .tses when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases when:tgnb.hl tompko.31 9 the gas expands.

In an isothermal process, 3700 J of work is done by an idep39z ukxoa*sk.2c-r d al gas. Is this enough information to tell how much heat has been added to t.akk3-*urzpo cd x9s 2he system? If so, how much?

Is it possible for the temperature of a system to remain x i7 cspj/0cp f)sx/yiax;8l+constant even though heat flows intol cpixx aif)0/7+x/js 8y;scp or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases wj8p2zh- py rxe9)2nughen it is adiabatically compresse-9gpyprxu2) 28h jn zed.

Can mechanical energy ever be transformed cw7kc5 n9qh)z(l5ed :z .jnbinompletely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, : nclh) z5 (zj qb.dwnkn9e57igive one or two examples.

Can you warm a kitchen in winte p,aey6i a/i4mfm ki7*r by leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door open? Explain p7 eai a/m6mi*ikfy4,.

Would a definition of he u9 w8y y)- op7ijr 3wrl4ggfcdr03gw2at engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature 2k6 pzn rqk1z96l nov+and low-temperature areas in (a) an internal combustion engine, and (b) a stezkp6+kvnr lon 6q29z 1am engine?

Which will give the greater improvement in the efficiency ofrin h58+pzp lj(-ijd 2 a Carnot engine, a jz2rp5-8h p j nil(di+10 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremend,a0u,xp dq r5jyrw-p3 ous amount of thermal (internal) energy. Why, in general, is it not possible to puty-0q, 5rw xj3u,papdr this energy to useful work?

A gas is allowed to expand (a) adiabaticallyvn vc x;)/;fb2xq j6utagc6w; and (b) isothermally. In each process, does the entropy increase, decrease, or stay the swuv)xtcjq; ;afx bc2n/ vg66;ame? Explain.

A gas can expand to twice its original volume either adiabaticadp88/yr x x93lfiy1c9(cd1x7ee s unolly or isothermally. 7lf3 dp (u1ye1 xo n9x9si8c/xed8 cyrWhich process would result in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of lq-en *ytog10naturally occurring processes in which order goes to disorder. Disc-1yl0t neg *qouss the observability of the reverse process.

Which do you think has the greater entropy, rj dd nuy5p9,81 kg of solid iron or 1 kg of liquid iron? Whd duyrj, 58pn9y?

(a) What happens if you remove theef5b +fk19j cm lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two5mck9e1f bjf+ other examples of irreversibility?

You are asked to test a machine that the inventor calp1 o f * -srhqy:cjfcp2k/9m/fls 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 switchefcmk-sr2 /p*of:1h jf/ pqc y9d 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 (other than those already mentioned) that would *6 (b,puxjji+od,(u1 bp oygfnk6/thfpn0f8obey the first law of thermodynamics, but, if they actually occurred, wpbx1j/6p tunoki h8u(0 o ,*6 (f +fg,jypbfndould violate the second law.

Suppose a lot of papers are 1z)8 ulxx,zhkstrewn all over the floor; then you stack them neatly. Does this violate the second law of thermodyx,u )1kz8xzhl namics? Explain.

The first law of thermodynamics is sometimq,-sbw3fi x 9sy81 bynes 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 stas9sy1by 8wi3 , -fqxnbtements.

Entropy is often called “time’s arrow” b jfy7y .d4yn-ahn +cz;ecause it tells us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that would tell you that ti yf-c+y.z4dn7j hyan; me was “running backward.”

Living organisms, as they grow, convert relatively s ,,(z: vdamu0; mcqycqimple food molecules into a complex structure. Is thi v0qcz u(,;mac,mq:yd s a violation of the second law of thermodynamics?

  An ideal gas expands d 73fsz6x s4asisothermally, 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 fittenw) nydl av+2+c6zff) (me.kpd with a light frictionless piston and maintained at atmospheric pressure. When 1400 +dyl m)e6)zfv2 +kp.f cnanw( 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 volumrezmp g.gu2 few 0rt0hc7; b93e is halved, and then it is allowed to expand isothermally back to its original voz0eb r;7pt3hug 2.r cemw9f0 glume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas at a81+uv5q7gji,zcjmlrxb:qapkm 0 9m 6tmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and8 5lp xigaqkvc m+j0zmr 691 ju,:mqb7 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 ayle82nmtf + y5t 4.5 atm of (absolute) pressure is allowed to expand isothermally until the pressure is 1 ny e+8f2ylm5t.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 halgev/zf 0ooeer06+3wix,j mzz ; nq2mn +8zs:ff slowly, while being kept in a container with rigid walls. +meo r:0 mnfn;jfeqz3v+ /g 8o,z is zzwx026eIn the process, 265 kJ of heat left the gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas is compressed adiabatically w0 qamp x.h(.(o ebouw)vi+y1to half its volumei(q0(hwxw. a o. bvpu)1omey+. In doing so, 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 at0vytjvu8mu31wzo1 :t a constant total pressure of 3.0 atm from 400 mL to 660 mL. He0z1tutuym 3wjo8 1v :vat then flows out 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 of2a ab4xc +2)ujoe/vck an ideal monatomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperkba x) euj/ oa4cc+2v2ature of the gas during this expansion?   $ K$

  Consider the following two-step process. oqv, ahr)w:*n0 z ok9qHeat is allowed to flow out of an ideal gas at constant volume so that its pressure drops from 2.0h*r9zoo) wa,v:qqkn 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 twoq7b.w-:ovi* .dr v evz9se, f j(.7egxi;zysu possible states of a system containing 1.35 moles of a monatb .,(sgzi*xsdf7:ee iz rouvv;yv .-7q wj.e9omic 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 a to c along th6wojjiovl-(* e curved path in Fig. 15–24, the work done by the gas i6-*jo voiwlj( s $W\,=\,-35\,J$ 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 stax 5y rt8 1gela:ly,7dfte a to state c along the curved path shown in Fig. 15–24, 80 J of heat leaves the system and 55rll:78 5 ,fy1aygdetx 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 transfor 3pzmi,tbm:: jm if instead of working 11.0 h she took a noontime break and m t,ijp::z3 mbran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate ol mte*mb-ff+yx9f67(h cv* 8j s ei5emf a person who sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daf e sl-i7jf5me*y+h*cx9vfme 8 tm6(bily.    $W$

  A person decides to lose weight by sleeping one hour less per day, using thl; h3pbm;wzp2 e 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;2wbzl 3m;ph p kg of fat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat wlfx de1e2g3)b hile performing 3200 J of useful work. Whbd1 x2el)fg 3eat is the efficiency of this engine?    %

  A heat engine does 9200 J of work per cy2h g(ql+ oeb,xcle while absorbing 22.0 kcal of heat from oxg(2blh+e, qa high-temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temperatures arb nx7n* blz -c 9mkslra .3w8b4*5i ydgzhmu4/e b879 wzbgnxm ia.ln4l-m*b dy s czr5u3*h k4/580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine /dt lg.whku;u3 inc+thv+0b x,ou1:u 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 (Carnot) azxt;w /p82dz efficiency between temperatures of taw2;z8 /dxzp 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 hea4 0.,tx:vx9zxuhq d,rkhi 25sic8ofat engine’s hot environment be hotter than ambient temperatur0:9.raho,vdt z2 s, qkxi5i4c 8xfhu xe. 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)?    %(Round to the nearest integer)

  A Carnot engine performs work at the i ;jk6he8 ;3 vi5p exee u1niw;etxa+)rate of 440 kW while using 680 kcal of heat per second. If the temperature of the hei+a;);h8utin6e eipxv;ke3e1 je w5x at source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatb pfm*ga cx 0m:u 5bo5dc+.g9sures 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. E inavdhnks*8zdq3 / s; 1g,8 gw:dqf/1p8 btsustimate the heat discharged per second, assumfd,bwdqg/z*/:8d ;n n sgq 1kt8a1 upsv8ihs3ing that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source at 550 4b70vjqqf p*w$^{\circ}\,C$ 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 heato)2no0gj.hc k,.lor6 et zq8nl0 1k ,xbfrh:c 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 fromgyy (v8hyvu.f+ cr//f one being the approximate heat input of the second. The operating temperatures of the firstyu+( vr fy/hc/fv g8.y 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 a8bzw/4ups u3+apeu2f3+smcs iy;wo 4jal: 0 d freezer cooling coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates with a 3 zk r2/xsrytd v+21uql9i j.mi,)kdy in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5.0.40qipt7o,itn/lm o; :sivp ) f If the temperature in the kitchen outside the ref)p io7tt fliqv0: n pos/,im;4rigerator 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 f6kjcfzmd6 eqv(,*:a nxj;d0 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 at om1 im p: /,xt4hpg2s9qldx4c 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 effis2u;(vk/xv t bhj// pnciency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficient ofb sj;kx/nu /v(/2htpv performance?   

  What is the change in entropy of 25.bdwzt 0ikg *bc:,9k1+b laf q0 g of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of waterwafdg2rtkh*8 fz+o*8 is heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entrob.j(yr1vtsxx0ywx;4 0 ja s8tpy 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 m 2rdo ua dm/.ru1i*d6speed 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 ground and coming rz9 jwr yp-0):rmy1mn to rest. What is the total change in entropy of the rock plus environment as a result p 0 y m1-wrmz)rny:9jrof this collision?

  An aluminum rod conducts c7v1xpvm:8 mrn ,e(fk $7.50\,cal/s$ 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 30a6k9 r wfg0)o: ld6pzw$^{\circ}\,C$ 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 alumin8 xah7q17 2tp7qhb ryxp0v(tkum 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 650 K m.9 fp9.hz1bk ne -qtoproduces 550 J of work per cycle for a heat input of 2200 J. otmh -nkp9b9z .fq.1 e
(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, oecsm g o8 nraq(*3sz*;zbo47c f 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 of increasing probability: (dzw g 8f4eubowyj 97:xlo.n:+ a) four aces and a king; (b) six of hearts, eight of diamonds, queen of clubs, three of hearts, jack of spades; (c) t79 n+.8bol:d 4ox ywwf:gzu ejwo 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 shaa6xqx5 hcxysf2zu6 *r.ae7 0kke six coins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probability of obtainin zeur6 axk5xsh yc20xq*6.af7g
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of electricity per squar-x vr e 2jr ;(czx.;mf0x1uqtce meter of surface area if directly ;vf0 x( 1urr 2cqjm.z;e xc-txfacing 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 peak demand by pumping water to e sd+j5 k2mlt f97kcenzxi/20a 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 rat/j0me 7cixkzf29k+es52dl nt e 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 artificiawa d7tktqb* 4*y0v 0aol lake created by a dam (Fig. 15–27). The water depth is 45 m007a*bd* aw o4vtyt qk 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 h16kd* b skly7rave designed and built an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and reject 67kdy1s kl*rbing 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 deliv 9 f-oax4tw/hgers 220 J of work xfw- ao/tgh94per cycle per cylinder. When the engine 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 (the reverse of fqypl:68sp;c jgnm+6a Carnot engine) absorbs heat from the freezer compart6;c6 ysnp:l+ pgf q8jmment 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 coufe784/qidq;) n9anzyattl -lld 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 ty q)dz ;4anlft9n-lq8a/7it e ropics, 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 travelinxj+hq +/,if mng in opposite directions when they collide and are brought to rest. Estimate the change in entrf m hinqxj+/,+opy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup at onzs4mboy84 l kdeo6v .1r (8n15$^{\circ}\,C$ 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 p u6t1lbx9n yf+ id+f3jerformance of an ideal heat pump that extracts heat f3duy+ nlxfif6bt9 +j1 rom 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 rq-nc0c(wcs9n/a s2 tf 4x /me*m1redueleases 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 lvkj9l;eo(n)s ower 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 sv6 drrffxgz 54tim -7l(y6v0ltate A to state C in Fig.trdvm7 5 -zfgll64r 0 y6i(xfv 15–28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Cooli*oep yehf/kra*u1f.sm02 ny yo)g7e 2d ,(gexng towers are used to take a aed 20. *oue2(fxr1kgy)gm,h*yn efops 7/yeway 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 energy at 980 MW usingwzku/o, )d(b vssvi6am 6pq+aa s9- mqb.s (y8 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 im( db-p iabsvs uo9 vq/y+z,s8(awkms6 6q.)adeal 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% e0 j,bxuzn9+u/tlw h3m fficiency. Assume the engine’s water tempelxu,jt9m3 hwn/+zb u 0rature 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 jar of8w*9 lfxu lwu0 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 fa ,relc/t6za i:u9k5wu t 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 condititymy3mobp lk . idnxhu87q2i-4z:2jzkhv 9 5-oner keeps the 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 an open d:o k z :/p0heb a+frj0k90zgxpoor.” 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 0o j0fk9pkg:+a/p0zhrzxe b: 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