What happens to the internal energy of water vaporo.b; ibj l b 1399-endsb*6wk nph-vzh in the air that condenses on the outside of a p.hhdn*ebbv-s b9z j-inw93;k 1obl6cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain whj)m 4v c*thr6xy the temperature of a gas increases when it is quickly compressed — say rcm* tj6hx)v4, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, kzv 2 mo99vr 3j+2e(4gp fhbkr3700 J of work is done by an ideal gas. Is this enough information to tell how much heat has been added to the system? If so, hopr9ov r 9me3gk(fv24 kh+jbz2w much?

Is it possible for the temperature of a s xyw-xn .j -yzda7mp)+ystem to remain constant even though heat flows into orxa-7y.x+ w-mzd yj) pn out of it? If so, give one or two examples.

Explain why the temperature of a t8+hbqq w+zn82 del e:gas increases when it is adiabatically compress:lnh+b + 8 wqz8dqte2eed.

Can mechanical energy ever be transj n6s+h0 (ebemm+ f)avformed completely into heat or internal energy? Can the reverse happen? In eaj(bhe e asmv06++ nm)fch case, if your answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in xr:l-b77tv(te. quuz )sq0jl ys:e2y winter by leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door o 2z.bqyvye-e0 )xst7uqt:sl :l(urj 7pen? Explain.

Would a definition of heatkxdou1 m /3l/xkd)z/4y*z cxs engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of hig,t4 dm.sbx;ox vo-br; h-temperature and low-temperature areas in (a) an internal combustion engine, and (b) a steam engine;bd t;m,r sb.ox4o-xv ?

Which will give the greater improvement in the effijp i 1xsdx):owd ;n,f.ciency of a Carnot engine, a 1d:x 1 i ndwf),.pj;xos0 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendo6mlnt h 76 lwrq,1gk kdr17r)ius amount of thermal (internal) energy. Why, in general, is it not possible to put this energy to useful 1) 67k6 1,7rdwr tkllgmn qihrwork?

A gas is allowed to expand (a) adiabatinyc cked+ -f 53-:wgvnhspd:2 cally and (b) isothermally. In each process p- w:cyfvneh3+dgcd-5k s:2n, does the entropy increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabatically or isotherma5hof2f im6gf) 7zjxu.e71mky lly. Which process would result in a greater change in entropy? Explaiozhmugj .2i7f 1 5f)6yfe 7xkmn.

Give three examples, othe gcp/q,ue9)7a laxa n.ia/ 3wpr than those mentioned in this Chapter, of naturally occurring processes inx pqc 9a/au./a3wa , )7egplin which order goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greate/y.53ao bvk (e 9febejr entropy, 1 kg of solid iron or 1 kg of liquid iron? Wh5ye9vk of b./b3( eajey?

(a) What happens if you remove the lid of a bottle containing c-vjtrm 6p-qplri63 v90fkj5 vhlorine gas? (b) Does t-l v3 jf0r6ipjrpvk96-tqv 5mhe reverse process ever happen? Why or why not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machiil 8bbp v5 )7qsxk 5;fb(asvu)ne that the inventor calls an “in-room air conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air coming out of it. How do you know that thi)(pau5k5qi bxb )l bv ssv;f78s machine cannot cool the room?

Think up several processes (other than thik jv,wh ff 7 ul2/3/;sv0mbkuose already mentioned) that would obey the first law of thermodynamics, but, if they actually occurr3; ,jluh2 0s/fk/ vwfb mviku7ed, would violate the second law.

Suppose a lot of papers are strewn all over the floor; then n/(6qn8km (gpxr f;rp;ji 1 izyou stack them neatly. Does this violate th (/18z 6g;prnixm q(;inp rkjfe second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stqxglgw1237 ijqw1nd 1ated as, “You can’t get somethn21q1iq xj7gl1 dw3wging for nothing,” and the second law as, “You can’t even break even.” Explain how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it fkm*x3nma9l+uua 1r dzyv()9 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 time was “runla+r9y)(3vn uuf*1 dxmmk9 zaning backward.”

Living organisms, as they grow, convert relatively simple :,s y9 *w osvef)gpd*fmj9t,h+ rzh(efood molecules into a complex structure. Is this a violation of the second law of t)o yjr 9tfv* * ,h,s9z(s+dgewmfhp:e hermodynamics?

  An ideal gas expands isothermaymo,cy2;3vno n.y- ck lly, 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 frictionless piston and mai65 7hytt/c: 1 *cnksppcx7z2wfdzbd(ntained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is obs tnh1d:d(*7 yzs/pf 5ct2 zxbpck wc76erved 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 presse lbd m7x8/ql5ure until its volume is halved, and then it is allowed to expand q78bl/e ldmx5 isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal) oqsi3tt-ah5diu ct ;;ui8p4 gas at atmospheric presss uth8a;ioi 4 - )utp5cit;dq3ure 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 reached.

A 1.0-L volume of air initially at 4.5 atm of (as,)77zq scirh mmu-g9d e*z y(bsolute) pressure 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 q9hei zzmu s7 7sdcrg*,y(m)- 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, whlaz x0.mo *uyg 7o*hh7g k*mezao/5o/ile being kept in a container with rigid wall a*75*e/o olh7h0o gm ma gz/*zyux.oks. In 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 idekh2p7sf 7/lk 1jg+fl xal gas is compressed adiabatically to half its volume. In doing 17s/j khlpflx+7 2f gkso, 1850 J of work is done on the gas.
(a) How much heat flows into or out of the gas?    $J$
(b) What is the change in internal energy of the gas?    $J$
(c) Does its temperature rise or fall? ----待选择----fallrise 

  An ideal gas expands at a constant total pressure of 3.0 atm from 4ng.kdow /. qspwy5i 8m (9dt:y00 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until the temiyqs:t9/mkg8 wn wpoyd..(5dperature 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 mnrm kf3c s9+u(onatomic gas expand adiabatically, performing 7500 J of work in the pror+39f nucsmk( cess. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step proce.auv6y/ gr e+mk: 5juybzf 1gq4;wlx*ss. Heat is allowed to flow out of an ideal gas atewy;+ :.z u61uv qf/g4la ky grmx5*jb 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. Calculate
(a) the total work done by the gas in the process,    $J$
(b) the change in internal energy of the gas in the process,    $J$
(c) the total heat flow into or out of the gas.    $J$  ----待选择----intoout  the gas

  The PV diagram in Fig. 15–23 shows two possible states of a system containing*my/ h,j5 ,kh s82xn,mkmgzyf 1.35 mo25*khy m,kj /f 8hgym,xns,zm les of 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 fro94*f /s0 lezhwlb;bw r07hd mvm a to c along the curved path in Fig. 15–24, the work done by thesl00w*zb/ 79rvlh;h mebwf d4 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 from state a to state c a4sskbj84p; lwjg*i *agq f) wg* 3zhm8long the curved path shown in Fig. 15–24, 80 J of heat leawz4*ba*gmw f*g k;s43g lq8jis)h j8pves 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 traoyqkh4 7d8/ g+4k, x42 j yoqpunlrja8nsform if instead of working 11.0 h she took a noontime break o2j /8 uy4p4q+k,4rxoy jd8 h7glkaqnand ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average mcqh* 2fqlh5 v4etabolic rate of a person who sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watcvq h*4lf5qh2ches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by5p uxd+uz ys(f zsb53b-nns9c6z8w8 3ucwq2r sleeping one hour 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 cu3 nzw6dw58bsqsz5c 8fuzsy29c-3p r+ unb(xhange 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 performing 32004sy3 /bk oe0yy J of useful work. What is the efficieny0sy 3yb o/k4ecy of this engine?    %

  A heat engine does 9200 J of work per cycle while ab(oh jgqc. msz*av5 5c2sorbing 22.0 kcal of heat from a high-temperature reservoir.aq(5cg h 5oc*jzs. vm2 What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose oper 2 jie :pl)d a*2uwxduim6*6paating temperatures are 5wjuil6pa x d* ed2mu:)a i6*2p80$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature ouor17y9;i)m;wg u4lvnn w)xbc6ay j/f 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 theoretical (cgn1c(qw;hg; Carnot) efficiency betweegn(1cc w h;qg;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 environ2 so d)eg+c q699cads o/pwu5vment be hotter than ambient temperatureowvq995c/ + ad cspugdse)62o. 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 rate of 440 kW whzdh8.qo*2 /8b yju q w8x1jqsqile using 680 kcal of heat per second. If the temperature of the heat source is 5 1d o8./zwusqqxh2 88jqbj*qy70$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatures are 21r jni /m)1+lb s;c/z0f1-dna d;spd nd0$^{\circ}\,C$ 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 dfp.,b v g*hxw2 q9(kzof electric power. Estimate the heat discharged per second, assuming that the plant has an efficxwd.q k p*9(fzb 2hvg,iency of 38%.    $MW$

  A heat engine utilizes0wju (j ,de+yimek9gc 05(xjd a heat source 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 i4h0ple ;a: 0u rl4kstyts 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 workmk:2he6dfm7 k )o.k ja in pairs, the output of heat from one being the aae kk).7fk m:j6mhd o2pproximate 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 cxti1q rpc3:94 pqeg0:s6b ack5u)hlm ooling 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 in a qhtfh7xl:; 3n24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance+nozd *5ilai) of 5.0. If the temperature in the kitchen outside the refr o*+n z)lia5diigerator 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 toa 9xzdm y)-h 0z.*tpit keep 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 0xib :s* 7wcdccl1jjqo gk:-:y5,tu0h $^{\circ}\,C$ 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 hasz:cl3dr8 h b 5/nuq g3pyg0f0r an efficiency of 35%. If it were possible to run it backward as a heat pump hl8: f30yb/ z ungr05gpd3cqr, what would be its coefficient of performance?   

  What is the change in entropy ofqps42k1e6zq e 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 heay:j;l86z0 2n,8kxebcps p2a6i n*v ztfg(sl pted from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy of ca9/+zp*e5sgxsx bj(lk+ay6 $1\,m^3$ 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 ogzytk 3d9 l8rk -cq,/lf $3.0m/s$ 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 jutxc v s14+vj1ust before striking the ground and coming to rest. + 4vcv1jt1s uxWhat is the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conducts (xkw pb8to2a+ $7.50\,cal/s$ from a heat source maintained at 240$^{\circ}\,C$ to a large body of water at 27$^{\circ}\,C$. Calculate the rate entropy increases per unit time in this process.   $\frac{J/K}{s}$

  1.0 kg of water at 30+o wngwknmkk( +q6-d 5$^{\circ}\,C$ is mixed with 1.0 kg of water at 60$^{\circ}\,C$ in a well-insulated container. Estimate the net change in entropy of the system.    $J/K$

  A 3.8-kg piece of aluminum 5oe uxzl 2z6z:hg i6 gi,s5fx*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 rx) key.).xgz seservoirs at 970 K and 650 K produces 550 J of.eg ).)syzxx k work per cycle for a heat input of 2200 J.
(a) Compare the efficiency of this real engine to that of an ideal (Carnot) engine.    % of ideal(Round to the nearest integer)
(b) Calculate the total entropy change of the universe per cycle of the real engine.    $J/K$
(c) Calculate the total entropy change of the universe per cycle of a Carnot engine operating between the same two temperatures.   

  Calculate the probabilities, when you throw two diq; k0o.2hze5 w ixkq:*w, pjcbq +nhz 90e*sjhce, 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,l+exg) oq1 tvuv3 j +;wcptb/ hands in order of increasing probability: (a) four aces and a king; (b) six of hearts, eight of diamonds, queen of clubs, three of hearts, jack of spades; (c) two jacks, two queens, and an ace; and (d) any hand having qp+oj ut b/v+1xtgl 3;wc ,e)vno 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 th ;.i.0ero/cjx2sjc(bv m amk *ba:9yc em on the floor. Construct a t c.;c b.eim2cjbjx(sak:*9o am/ vry0able showing the number of microstates that correspond to each macrostate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of electricity per squara+0zxyiya,1l8* 6glv p n0d xne meter of surface area if directly facing the Sun. How large an area dilyxlyxp*8g+a z0v, n0n6 1ais 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 a i n:,x fvm1bk h63ob/rw6vpj e6qi* tkqkq3**high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumtvoir6 ek *niqw3kv6/*px1*hqbq3 ,jfkm:6bped 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 ac0hssyje,tiy mv(;wma92x h9t g5 )3t dam (Fig. 15–27). The water depth is 45 m at the dam, and a steady flow res;w 2vtjx)ma y(hs cm 9g,t5i90yh3tate 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 anx3wi)ce3qeu hpn* 09 5h5gm0m3 kihyn sgd-v3 d built 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 thermal energy at 215 K. Is there anything f)v-eq3ipi0hg3g53n9ynsu* mch 3w hxek d50mishy 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 m02ehm28w5 byh/eul ,l bc p3mengine has an efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine firel8 hemuhp03w/b2m e52l , bycms 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 a Carnot engine) absorby03g 9;vkwl0gfxf id1 s heat from the freeze3x0w9glyi1 fdgvf0; k r 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 be developed that made use o1 uwl)3f,1a qmhy2oe if the temperature difference bemao 12 w1,3f)qey huiltween 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 when they collide and av8m eki,khc9 t*m57at+3xg pyre brought to rest. Estimate the change in entropy of the universe as a re3* ethm9,atgi58k pmck v+yx7sult of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup a/vo0*ul u*yb s09un ;evfzs3vt 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 idefp+6 kmuu)4 ipal heat pump that extracts heatfp 46i)+mpuku from 6$^{\circ}\,C$ air outside and deposits heat inside your house at 24$^{\circ}\,C$?   
(b) If this heat pump operates on 1200 W of electrical power, what is the maximum heat it can deliver into your house each hour?    $ \times10^{ 7}J$

  The burning of gasoline in a car rel nxrhr5cd4, 2reases 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 operxqc (fzo 6 4p6vjz+)ujvc0nc;ating 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 m4q05 wiyiw4 xby an ideal gas in going from state A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC direiwxwm 0 5qi44yctly.

  A 33% efficient power plant puts out b+xsvp3yqq70it+c7 c 850 MW of electrical power. Cooling towers are used to take away tq bs+c0v3ptc7 7+ qyxihe 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 using steam turbines. The ss:wgij5t9 wa*team goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K 5*wiastw:gj9. 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% efficiency. Assume thejf c8sl. vg/ p).ilqy4 engine’s water temperature of 8 lf.lj4 8p)iq ./gysvc5$^{\circ}\,C$ 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 placed7ezipquc717 b in a tall 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:b 4/g9v wjts7xg ukt1 fat results in about $ 3.7\times10^{7 }J$ of internal energy in the body.
(a) In one day, how much fat does the body burn to maintain the body temperature of a person staying in bed and metabolizing at an average rate of 95 W? $\approx$ =    $kg/d$(retain two decimal places)
(b) How long would it take to burn 1.0-kg of fat this way assuming there is no food intake?    d

  An ideal air conditioner keeps df efliufsy*388gu94 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 door.smxlh)odyre 3y7s, ,5 ” 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 3,l xo7 s5ys),yedrmhfrom 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