What happens to the internal energy of water vapor d f)6zlj p0262cdn9c 2v tu yjnky/za4in the air that condenses on the outside of a cold g69z yk/0ndtzjvf4j2lcn2 ca2 up)6yd lass of water? Is work done or heat exchanged? Explain.

Use the conservation of er8g.7 xzcg) lup v*ot,iz3lg *nergy to explain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases when thev*3rz c,)8 7pgglxouzgi*t l . gas expands.

In an isothermal process, 3700 J of work is done by an ideal gas* irwesny2*g*. Is this enough information to tell how*ni2 *yegsrw* much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system to remain c8 qn3u95xfq8k a kbj9er+jix5 onstant even though heat flows into or out of it? If so, give one or two examples i+k8j3fk8r5 u9a59jqnxeqxb.

Explain why the temperature of a gas increases when it is adiabatically comprm7 r es p2i o/v)h;3u2 v;m7drkmsldh/jtp4n+essm ksvdm+ ;prpu2/ 7to4 7)smlivhe;3rdhn2/ jed.

Can mechanical energy ever be transformed completely into heat n3s5az:w ds7au /f eu5or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one or two exzasef dsu5u7aw3:5n / amples.

Can you warm a kitchen in winter dqle*sf n ,,,x8lzcwf:t+tuawqq .w f d3b54,by leaving the oven door open? Can you cool thew w,t,qltu fzb5f q,q3xds.,:c84e*wfla+dn kitchen on a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of hea e.k j9-vj( k.rvcvz-st engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of4)z agxhd) ib i)u5 v.ojz/jk6 sg10ai high-temperature and low-temperature areas in (a) an internal combustioxs.j oaiag 50zv/hid uj)1g4b)i 6)kzn engine, and (b) a steam engine?

Which will give the greater improvement in tyxb3sw 1rs:oa; 8d ;)vrc k/zfhe efficiency of a Carnot engine, a 10 8/b;r fzadsy) :srxco ;kw1v3$C^{\circ }$ increase in the high-temperature reservoir, or a 10 $C^{\circ }$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous amount of thermal (internal)way;sb;q hv65x( st -s energy. Why, in general, is it not possiblw(sx;-yqs h; tv5bsa6 e to put this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) isothermally. In each proo9v f2ycke5dg yp1dq +(c1+oq cess, does the entropp+od+d1qe 5ygcqf c( kv21oy 9y increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabatically or isotp7: +c1d ib+xy1dg zimhermally. Which process would result in a greater change:xdzm y d+b1 gpi17c+i in entropy? Explain.

Give three examples, other than those mentioned zj5 lc9w,0vtr1 a1abu n pe8o0in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss0jr8poc tn019lub, 5 z1ewv aa the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of gzwz0+l+afil 2 um+) dsolid iron or 1 kg of liquid f+)w ++2a zmlzg udi0liron? Why?

(a) What happens if you remove the lid of aepevq8.r 3x9 e bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can yo 9vq.ex8 3repeu think of two other examples of irreversibility?

You are asked to test a machine that the invef qnwfis1*9qy3 i(b2k w i)nt;hiio-:ntor calls an “in-room air conditioner”: a big :fni19*w ho ysi)w(t ;iq3i2 -b fnkiqbox, 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 this machine cannot cool the room?

Think up several processes (other than those already mentioned) that wou(yec7ml kqel.zfsm , 52mb8:rld obey the first law of thermodynamic2,:.y857meqblefz (mkrm slcs, but, if they actually occurred, would violate the second law.

Suppose a lot of papers are strewn all over the floor; then you stack thtmyuk05cj n b+c-g: 6idx 2h-qem neatly. Does this violate the second law of thermodynamics? Explai5n yd c-ij:+qxc k 0htu6g-mb2n.

The first law of thermodynamics is sometimes whimsically state8vi 3xye*gi*c9nn 7hqd as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how 7i ygnx ih9 v**8nq3ecthese statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it tells us in whi 2ogl*i5;is kra.me ip m(w;-vch direction natural processes occur. If a movie were run backward, name some processes that you might pr2i; ( .-ig m*5w;lovesi kamsee that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simple food mob qrj(w0s2ak ,lecules into a complex structure. Is this a viqb0,ws(ka 2j rolation of the second law of thermodynamics?

  An ideal gas expands isothermally, perf (rnod.d*s*-smcvgb3o9 b, zporming $3.40\times {10}^{3}J$ 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 fittzln3g).umfwkha r5 (i9xv2i+ed with a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is fa nh9v z(ugwrlimxi .3)2 k+5observed to increase slowly from $12m^3$ to $18.2m^3$ Calculate
(a) the work done by the gas .   $\times {10}^5$
(b) the change in internal energy of the gas.    $\times {10}^6$

One liter of air is cooled at constant pressure until its volume is n+zngzm3bnk* )aa l, . rt74bghalved, and t4rnm*b knn,7 tga3l).b zg z+ahen it is allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of th+fpf-opn yl9a n*9m 3zi3:jfme following 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 imfjy9p*393: lf mno+n zpfa -pressure is increased at constant volume until the original pressure is reached.

A 1.0-L volume of airatgojs ) ott-q xv2/;: initially at 4.5 atm of (absolute) 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 constana2/ xs qjgoot-v:t ;)tt volume. Draw the process on a PV diagram, including numbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while being kept in a con2ezb4 epct).p tainer with rigid walls. In the process, 265 kJ of c.bep42zep )theat 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 almo+l kw;bkv3/i8/.c,o3rgok;v ah mgalst ideal gas is compressed adiabatically to half its volume. In doing so, 1850 J of work is done on the k hmarow/ +lc8a,v3;/ 3kib;koglv g.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 constant0iq7zsut u2m+* z57wjn tw-hn 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 all-u5wh0 njt iu* sq7+7t z2nwzmowed 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 adiabatically, ;h3f3+ hghb(. ,sfuetzu+oci/ .n hpix0wwx) performing 7500 J o.p .i3f(s ,h +ziuf+hxgth0w h;b c u/enw3)xof work in the process. What is the change in temperature of the gas during this expansion?   $K$

  Consider the following two-step process. Heat is allowed fdb o c+2whb-;0u wipq195w ylto flow out of an ideal gas at constant volume so that its pressure drops from 2.2 dl 0f+u 9hcb5w1wq b;p-2yowi 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. 15–238aqtd;ub vt0zeu ., /b shows two possible states of a system containing 1.35 moles of a mona8v.bu ,audzt /e bt;q0tomic 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 =    $J$ $\mathrm{\Delta }U$ =    $J$
(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 c/rf f7j.sy0 7 cb9vefv ;evdea19/ijalong the curved path in Fig. 15–24, the work done by the cf;yjeve iav/ejs. fv9dcf b7 /r0197gas is $W=-35J$ and the heat added to the gas is $Q=-63J$ Along path abc, the work done is $W=-48J$
(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 stacn5y kv vybbq:319kt* te c along the curved path shown in Fig. 15–24, 80 Jk 5vc9k*:t3y nbv bq1y of heat leaves the system and 55 J of work is done on the system.
(a) Determine the change in internal energy, $U_a-U_c$.    $J$
(b) When the gas is taken along the path cda, the work done by the gas is How much heat Q is added to the gas in the process cda?    $J$
(c) If $P_a=2.5P_d$ how much work is done by the gas in the process abc?    $J$
(d) What is Q for path abc?    $J$
(e) If $U_a-U_b=10J$ what is Q for the process bc?    $J$
Here is a summary of what is given:
$\begin{array}{rl}{Q}_{\mathrm{a}\to \mathrm{c}}& =-80\mathrm{J}\\ W_{\mathrm{a}\to \mathrm{c}}& =-55\mathrm{J}\\ W_{\mathrm{cda}}& =38\mathrm{J}\\ U_{\mathrm{a}}-U_{\mathrm{b}}& =10\mathrm{J}\\ P_{\mathrm{d}}& =2.5P_{\mathrm{d}}.\end{array}$

  How much energy would the person of Example 15–8 tran8gat-yzia63xg s b 8 91tkz3t0bogp- jsform if instead of working 11.0 h she took a noontime br0tytgbsak t3 og pzjx98 b1-- 6a3giz8eak and ran for 1.0 h?    $\times {10}^{7}J$

  Calculate the average metabolic rate of a person who sleepslooz..od8. bjh eo 6c76 ku7x ns*7doo 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 zu7.6 cdnsooo 7x6 b*h8. lodoo k7j.e0.5 h daily.    $W$

  A person decides to lose 4 o7 gymt0k8c9yx xul/rj/l, aweight by 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 change in food intake? Assume that 1 kg of fat storextlo/xgy74 k8um l, jaycr09/ s about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while perfor vgmw6v83gqk.ming 3200 J of useful work. What is t mgw3kvg.q86 vhe efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbid7i;-nb8z; t5cokb skng 22.0 kcal of heat from a high-temperature reservoir. What is the efficiency of thiscktb-;k7i58 do nb zs; engine?    %

  What is the maximum efficiency of a heat engine whose operating tempgmxvmt nayfc4q /j73:mc ,w+9 eratures are 58 f 9,c:7gmcaytwq/nv mx3jm +40${}^{\circ }C$ and 380${}^{\circ }C$?   %

  The exhaust temperature of a heat engine.yu50n *g 5gb+ vofwge 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 (Carnotwrn cz:rh5 p(+ dl94q..l ewy x9t th5kb.wt0m) efficiency betweehz l.wkr : lhbmqwpx9d9(5w ett0r.ny4tc.+ 5n 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?    $\times {10}^{13}J/h$

  It is not necessary that a heat engine’s hot ey/(6d 0kbss djnvironment be hotter than ambient temperature. Liqui/dd k(6sbyj s0d 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 tv.4kyrdq 0o0tn udhxh p ,f76.he rate of 440 kW while using 680 kcal of heat per second. If the te v oxh.fnu ,rddy6ph70tkq.04mperature of the heat source is 570${}^{\circ }C$, at what temperature is the waste heat exhausted?    ${}^{\circ }C$

  A Carnot engine’s operating temperatures are 22jjcaik38u .d g+2jptd9p 9zt ;:h dcb10${}^{\circ }C$ 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 pg j ,b3p;uy;n,ir /ypdower. Estimate the heat discharged per second, assuming that the plant has an efficiency ofduin yjr/;p ;b 3yg,p, 38%.    $MW$

  A heat engine utilizes a heyg y 3.a)lpc)bat 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 exhausubsw/hp a+w4g)jz9v ;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 engines work in ).r* 0cnp7)ow :v8m1gfjhyuh;bamt jpairs, the output of heat from one being0 f:mg bc8 aou; )* 7)hhw.vn1yjpmtjr the approximate heat input of the second. The operating temperatures of the first are 670${}^{\circ }C$ and 440${}^{\circ }C$, and of the second 430${}^{\circ }C$ and 290${}^{\circ }C$. If the heat of combustion of coal is $2.8\times {10}^{7}J/kg$ at what rate must coal be burned if the plant is to put out 1100 MW of power? Assume the efficiency of the engines is 60% of the ideal (Carnot) efficiency.    $kg/s$

  The low temperature of a freezer cooling coil a2bq ( l1w ,qmwgjfr,:is -15${}^{\circ }C$ and the discharge temperature is 30${}^{\circ }C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer oper wg* ;88os b;3hzool 4:/a7coixaiweaates with a in a 24${}^{\circ }C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has fg4vzxe9y :p/tvq 1b9 a coefficient of performance of 5.0. If the temperature y9petvbq x1/z9: 4v gfin 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 house warm8)eag**a6iduq9pocl h .1uz u 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 a pyzipltnrv 5*)u: m22t 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) enginen* qbtp0 ,)dpmqa5 r0j has an efficiency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficient of perfon) d,qapr b05*jqpt0 mrmance?   

  What is the change in entropy)6xp-g1t7xl 1 xj qhxl 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 heated /kxb*h )w vqjjc 1h (h7z./bgzfrom 0${}^{\circ }C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy of.iv i;zkqma-szt j. -6 $1m^3$ of water at 0${}^{\circ }C$ when it is frozen to ice at 0${}^{\circ }C$?   $\times {10}^{6}J/K$

  If $1.00m^3$ 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 3 -np) scwy)yz+4pwlm 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 kine +m(7d.badw*qu)cmq)eo 5e ui tic energy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment as a resul5io*e amu . +dwdemuq7)b( )qct of this collision?

  An aluminum rod conductsh/pl9y i lsgpdh+1t( a d*8*nb $7.50cal/s$ 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 30w oqo)xanl6y2 .j98bsfc.q c7${}^{\circ }C$ 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 aluminumhl2hq93ryq /ynbq s :)um 6f-v 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 awc9v s1 mxsku/l. ;kw9nd 650 K produces 550 J of work per cycle forvk;9 m9 1c sk/x.wwslu 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 probabilita3b gaw6i /mk*9vqxl l )u-+mnies, when you throw two dice, of obtaining
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hands in ok/1 mdzk)veftgv+) i 0rder 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 cards. Discuss your ranking in vde+vkz)/f1m0 itk) gterms of microstates and macrostates.

  Suppose that you repeatedly shakq:3gpw5tc* kgju u/ /c9* 8nc0qhvr hle 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 cjrhkgcl0 /qpv h9ug/5*tuq83wn*c :g
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce/hqim1ydg)wmpm 6lh*mo- ; + x about 40 W of electricity per square meter of surface area if di m*) xw1h m+hm-yg/d poq6;mlirectly facing the Sun. How large an area is required to supply the needs of a house that requires $22kWh/day$ 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 higf .nwmn6 9w c w9vav.v.yfu9f6h reservoir when dema 9 wf.9v w6.nm9.vcvnyufw6fand 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 rate of $1.00\times {10}^{5}kg/s$ for 10.0 h at night.
(a) How much energy (kWh) is needed to do this each night?    $\times {10}^{9}W\cdot h$
(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 1r7a+wm+svd/:y u+ rkomug +fcreated by a dam (Fig. 15–27). The water depth is 45 m at the dam, and a steadkwsurgoy+rdu: m1+/+ av +7mfy 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?    $\times {10}^{7}W$

  An inventor claims to have designed h7lr f-xtw.gvxm4 k0 cv4rr:k44ny-c)+fk q jand built an engine that produces 1.50 MW ofgj 4 v n frxkkkhxrvlyc47)-w:4qt0f.4c-+rm 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? Explain.  ----待选择----yesno 

  When $5.30\times {10}^{4}J$ 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,    $\times {10}^{5}J$
(b) the change in internal energy of the gas.    $\times {10}^{5}J$
(c) Graph this process on a PV diagram.

  A 4-cylinder gasoline ejjppk;u g/.p)ngine has an efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cpg k jjp.pu;/)ycles per second,
(a) what is the work done per second?    $\times {10}^{4}J/s$
(b) What is the total heat input per second from the fuel?    $\times {10}^{5}J/s$
(c) If the energy content of gasoline is 35 MJ per liter, how long does one liter last?    s

  A “Carnot” refrigerator (thcz*nuv q.f: +me reverse of a Carnot engine) absorbs heat from the freezer compartment at a temperature of -u+n .zmc*:qfv 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${}^{\circ }C$    $\times {10}^{4}J$
(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 thacy+z .uubf v. v2,0t 7s6yesxft made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the fv0s+cyu2 7 xe6,fut.b.z v ystemperatures 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 collvnm)h(2 orau e;z+b: cide and are brought to rest. Ezh:) ne br(+vca ;m2uostimate the change in entropy of the universe as a result of this collision. Assume $T={20}^{\circ }C$    $J/K$

  A 120-g insulated aluminum cup ajs 1k1xpl40vh)r*n6 ioiho pj8:,ib v t 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 okcdud/ ) 5n.rk+ l1ne(qyva;ideal heat pump that extracts heat anyod)ek(k c+;.ul r5 vq /dn1from 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?    $\times {10}^{7}J$

  The burning of gasoline in a *ah4 .md 3erkrcar releases about $3.0\times {10}^{4}kcal/gal$ 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 lor2b wst*1n6v bz23u)yp vawi 4wer 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 going8a cms1,)9wkyxf j2hu-6fk ht from state A to state C in Fig. 15–28 for w, yk82 xth6-fmu9 fshcaj1)keach of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant putsvlcu sh3n*0 5rwar dz/ a+1gu8u/bayhw ;l+p5 out 850 MW of electrical power. Cooling towers are used/r 5h unu+35/u8zwgbv0 dscy*ha pw+;lraa 1l to take away the exhaust heat.
(a) If the air temperature is allowed to rise 7.0 $C^{\circ }$, estimate what volume of air $(L{M}^3)$ is heated per day. Will the local climate be heated significantly? $\approx$   $k{m}^3/day$(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.    $k{m}^2$

  Suppose a power plant delivers energy at 980 al k2- -q1sv85irlm yfMW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. -q1-l ms2filky8a5rv 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% ezz:tlz. k1)tpt540ee; lxk;e 7 jqnt vfficiency. Assume the engine’s water temperaturl ete1). q 7ztlx n;v:5;kzjezt4tk0p e 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 $Q_L$ =    $\times {10}^{9}J$ $Q_L$ =    $\times {10}^{5}kcal$

  An ideal gas is placed in a tall cylindrical jar of cross-secf5 x5i z x0hvlxhi;-i0tional 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 ox 8gwf*.f: fg*r-ehbxgj 8/e+ad1 rpof fat results in about $3.7\times {10}^{7}J$ 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 inside a room at lig4 5nt- v+yq21${}^{\circ }C$ 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 “r 8kpnyb8, o.t7jfyn 66y/ssfa efrigerator 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 ai t.y8nns /jsyky678ao ,fpfb6r’s water condenses. After this water is extracted, the air is warmed back to its original temperature and sent into the room. In a well-designed dehumidifier, the heat is exchanged between the incoming and outgoing air. This way the heat that is removed by the refrigerator coil mostly comes from the condensation of water vapor to liquid. Estimate how much water is removed in 1.0 h by an ideal dehumidifier, if the temperature of the room is 25${}^{\circ }C$, the water condenses at 8${}^{\circ }C$, and the dehumidifier does work at the rate of 600 W of electrical power.    kg