What happens to the internaprfh*s, l ee 0x7+y:dll energy of water vapor in the air that condenses on the outside of a cold glass of water? Is work do, +x releyd0*slh:pf7ne or heat exchanged? Explain.

Use the conservation of energy to explain why the te9 p1npkg)au xabl3jq *)e /f9gmperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases whenf ljp)xe 9na u9g)gabpk1 q*/3 the gas expands.

In an isothermal process, 3700 J of work is done by an ideal gas. Is this so8sda-hn .vyad/y.4enough information to tell how much heat has been added to t -o y/v.4 a8yas.dhdsnhe system? If so, how much?

Is it possible for the temperature of a system to rem bb:u0c uf*yo6ain constant even though heat flows into or out of it? If so, give ou* ycb uf:06bone or two examples.

Explain why the temperature of a gas increases when it is adiabatically co*7 ,t anap.+tl/c ttrq-j(op e**rfwsp+/lwjmpresstqprt (ap *7 n/rp*/jljf-t,+ot e laww.+cs*ed.

Can mechanical energy ever bf ew jlx;cig.us)a,ymu27;z/e transformed completely into heat or internal energy? Can the reverse happec;;ulsfu, je /mawyx7i2 .g)zn? In each case, if your answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the o4x.ol 4m/cu;ji4 *vbdxzyh4 kven door open? Can you cool the kitchen on a hot su* .ijuy4k o xcd;bl4z 4x4m/hvmmer day by leaving the refrigerator door open? Explain.

Would a definition of hea +;-ax j j1h gwx6t:p9odn2zeezipo+(t engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature atfeb 7b yq00n(reas in (a) an internal combustion engine, and (b) a steam (qyfn07bebt 0 engine?

Which will give the greater improvement in the efficiency of a Carnot enginswamku*w5x+ . i +rev iogv ,1ba6fc8*e, a 10wo6 +8i agc5 *vkerwm f*. x1+vbiau,s $C^{\circ}\,$ 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) energy. Why, inm6 gv/eop+sa dxocz;97o ; jh* general, is it not possible to put this xpa zs;d o+v/eo*ogh9j; 6cm7 energy to useful work?

A gas is allowed to expand (a) adiabatically andid;q* +33go 9kji9lv qnisg :n (b) isothermally. In each process, does the entroik;j*s+ vg oigi nn3dq:l39q9py increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volq9 :criq,s h4yume either adiabatically or isothermally. Which process would result in a greater change in qsicq:,4r9 y hentropy? Explain.

Give three examples, other than those meq 8o4;ia8i ybpntioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss thei q8apbi4 ;8yo observability of the reverse process.

Which do you think has the greater entropy,llqkuq84; iqx- bd l.4 1 kg of solid iron or 1 kg of liquid iron? Wu.q84q bklli qld;x-4hy?

(a) What happens if you remove the lid.b wxs d am; y5h6ong* f*kd)4ha6waw5 of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other exw5h 5 6h4df).6asw k*adnoy gmbxa*; wamples of irreversibility?

You are asked to test a machine that the inventor calln;o:n ,r :wjcbjicx 48s an “in-room air conditioner”: a big box, standing in the middle c :o 48rb jcnwx:,ni;jof 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 processe4r 1j0 aoqjt- riyej)(s (other than those already mentioned) that would obey the first law of thermodynamics, but, if they actually oc(1e-j0jrqo i)r jyat4curred, would violate the second law.

Suppose a lot of paperrl( bvny g6r,-b.yf49 :qyapx2n hu0ws are strewn all over the floor; then you stack them neatly. Does this violate the second law of thermo26qawnbv0lny 4r-x,gb(yhp fr . :9uy dynamics? Explain.

The first law of thermodynamics is sometim u uh)-w4: x8 swffc*apz60ccces whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how th)0x*wfucc :f46 cczp aus- 8hwese statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it tells us in which directi t9v(m1m z n)bv,kbow3on natural processes occur. If a movie were run bav 9)tb b1, m(zwm3onvkckward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatijmr-h )+aex; h6v*uqc/ hcz5vvely simple food molecules into a complex s uma)-vjheczr;hvhc6/q + 5x*tructure. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, po x;9 e5 42/aroqjqgsn/r9rhzerforming $ 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 fit3c6 c /,/jq;r7nrf toak6ihq4(xzd p gted with a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is observed to incr/g(4z3r /ifk q6cx to;d6jhrnp7,cq aease 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 ahs;lqd(f 0we *q,a k,is halved, and then it is allo, lwah efs* qka;(q0,dwed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following procec / 0)eq3 ,m6med kgz 8i5miqj+xmda6dss: 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 ba5imcdd8mdmqk ,zig/e)a6e3jm x0q6+ ck to 2.0 L, whereupon the pressure is increased at constant volume until the original pressure is reached.

A 1.0-L volume of ait::ndl3 x6ytvr 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 constant volume. Draw the process on a PV diagram, including numbers and labels fo 6 ::txnvydlt3r the axes.

  The pressure in an ideal gas is cut in half slowly, while being k:k.xew *iuow j7nu) d8ept in a container with rigwi* 8)k:7x.uwo denuj id walls. 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 ideal x( zl;w;xac,csj (jbt 9v46jr gas is compressed adiabatically to half its volume. In doing so, 1850 a j c6 s;bjj9(x,lt4zc;vw( xrJ 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 const rf5qz*bge:/ pant 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 a :*zerbqg 5/fpre 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 of an ideal mo9n .lbx*ou7yn- htrt.natomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the gas durin* t9n.- ulh.7xnytobrg this expansion?   $ K$

  Consider the following two-step process. Head5r-sk(21 jw lmfbk:mt is 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 temperaturkm s r b(:d-1w2j5lkmfe 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 xj8 l0x ecr/vo; jsns3;nci;h,w9o8 wstates of a system containing 1.35 moles of a monat3; co j;slvc/hsi ;rw8wx0n98joxe ,nomic 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 fx5( .wc1aubbs rom a to c along the curved path in Fig. 15–24, the work done by t1s.b u5b (acwxhe 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 styjefi qyi;s: xa7.; *mate c along the curved path shojqi sa ;xyeymi ;f7.:*wn in Fig. 15–24, 80 J 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 $U_a-U_b\,=\,10\,J$ 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 instead6*(byz1 iypn b:9qz ox of working 11.0 h she tookyyobx (i:*b1zp 9q6zn a noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average mese8 qmlgfgejbstir/t 6a.- */(l d11h tabolic rate of 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 h8i /jldseal(/tbg r6t1fe* qsghm1-. daily.    $W$

  A person decides to lose weight by sleepinapnr me,7. f5xmxe8 nm-7cc6hg 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 stores about 40,00r m.5m a,cm86pec7-7hxxef nn0 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while performing 3200 J of usefx-9w 4tqilye;ul work. What is t;4 -wt 9xieyqlhe efficiency of this engine?    %

  A heat engine does 9200 J of work p*n, zr qd7x-z +bhn6 ,yncph3yer cycle while absorbing 22.0 kcal of heat from a high-temperature 7,zby cx*z+ rp nnqhdh6n y-,3reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a he/co jsc.j 36-dzoblr *;1ez pcat engine whose operating temperatures are 580rp* b3e.jocs-/d;ojcc16 lzz $^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature oxpfjjollf1 t/2/owcg:e h 1,1f 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 operajqw5p-e acj9de ---nh p +ovy1tes at 75% of its maximum theoretical (Carnot) efficiency between temperat-5c9na qd-jp 1yh-o+ - wpjveeures 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 enginefyy0* xq pw7u:wn :u45c/kszg ’s hot environment be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the efficiency of an engine that made use of heat transferred from air at room temperature (293 K) to the/ *k:u 5yf:qyzuw s7cpn0xg4w liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work bu*q;w. c* b k4mujwt)at the rate of 440 kW while using 680 kcal of heat per second. If the temperature of the qt)4jcw w*k*. ;mubu bheat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temper,de cbh4+5,( yzcpkuiatures 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 elecnw) mmhu xuvl5b/w,7 - i(9cortric power. Estimate the heat discharged per secocu -o l7(iwu9)vmr /m xhbnw5,nd, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source at 55mp+b9j 2rn s/s0$^{\circ}\,C$ 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 itsfk) w/ ;it6vc zu,zi94(jdtjy 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 engine dhan,xzv nwaag6* ( p8c,8uz,s work in pairs, the output of heat from one being the approximate heat inpca ,(z68 ,z*nanga,p uxwv8h dut 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 cooling 1;adoh k gqruw-42*stz 5ps1hcoil 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 nl z)gorg 3uo,c ;8naei/ 5ct: in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficiental mtu*0sto6*q+ c**cgyz, fr of performance of 5.0. If the temperature in the kitchen ou6c+*sf,*a qugol*t*yc0tz mr tside 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 warm f hm*-j9hv7j*pkg+h yat 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 lv:8.d4ax wxnat 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 3zm1lys* k)j szk yd;:ayxxt5 ); /v.lw5%. If it were possible to run it backward as a heat pump, what would be its coefficient of p)k. ljx;mt*yd1: as ys vw/k yx5;z)zlerformance?   

  What is the change in esb: ,inm9x4hentropy 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 ispbt;zw qvpjen( l1x,6(qf l38 heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in ekgn(hz: c8h 1tqo+uo ;ntropy 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 initi- 3j7 gixzc3bcsjrl/ +al speed of $3.0m/s$ slides along a rough table and comes to rest. Estimate the total change in entropy of the universe. Assume all objects are at room temperature (293 K).   $J/K$

A falling rock has kinetic energy KE just before striking the ground zb9rwca tf gkx-(gu 4t38wvy *xe-4n0and coming to rest. Whattgn *3-w(r8 ab9-t v4 x xwezfyg4u0ck is the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod cond1fp2 mhgk/y+pucts $7.50\,cal/s$ 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 30j8pb kveqxlj ud/g 9b6,no)d3e.o t ,0$^{\circ}\,C$ 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 alumqb:xmr- wnf b6 e36gncw 5;ph9inum 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 t9dks:i2h*u .bp/pe iK and 650 K produces 550 J of works.:i*b t/9 k hud2eppi 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 probabilis1 disun /9lv;ties, 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 wlmobm pc7k+ :g -p.6pku vt25in order of increasing probability: (a) four aces and a king; (b) six of hearts, eib m.2t kplmwv: 7u65kcp-+pogght 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 terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and drop them on tqsvqgoz7- 7z95 rzi mz rcy9/0he floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the pro9zzq 0r/9smygvq z7 r7ic o5-zbability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of eleczw,v zl3hon0x :9nn b*tricity per square meter of surface area if directly facing the Sun. How large an area is required to supply the needs of a house that requirzhl,: w*nv9bz 3n0nxoes $22k\,Wh/day$ 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 pumpi 6-k xrc,b(:m2fk hduong water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose watedck-, rh: xom6bu2(f kr is pumped 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 4uvpx95f rs+t lake created by a dam (Fig. 15–27). The water depth is 45 m at the dam, and a steady flow rate t+4fu9x 5psvrof $35m^3/s$ 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 8.x4 v ptf2t*mz vloa4adnw,7 pd.r, vbuilt 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 thermalvdfv8.4atm* ,7d2 a tx,v. pz4rnw pol energy at 215 K. Is there anything fishy about his claim? Explain.  ----待选择----yesno 

  When $ 5.30\times10^{ 4}J$ of heat is added to a gas enclosed in a cylinder fitted with a light frictionless piston maintained at atmospheric pressure, the volume is observed to increase from $1.9m^3$ to $4.1m^3$ Calculate
(a) the work done by the gas,    $ \times10^{5 }J$
(b) the change in internal energy of the gas.    $ \times10^{5 }J$
(c) Graph this process on a PV diagram.

  A 4-cylinder gasoline engine has an efficiency of 0.25 and delivers 220 J of w2fr kaf94s*sqg9 tt5 vork pksgvtt9a*q fs r 54f29er 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 f0dd*rxfelun7e (uz b ;;( yq;of a Carnot engine) absorbs heat from the freezer compartment at a temperffuz qdy7 *xe;l (e;0(n;rdu bature 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 thai4dcbhdh gj ) l73bg:4vvlszi )u.+d*t made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures l dl)4i bh4:vvgus+*7j b)h3i zdc.gdmay 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 trav,o (beengl7)j eling in opposite directions when they collide and are brought to rest. Estimate the change inb7l )o ngje(e, entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum c/-pntu +z 6:t:bclaf/3fz u hkup at 15$^{\circ}\,C$ is filled with 140 g of water at 50$^{\circ}\,C$. After a few minutes, equilibrium is reached.
(a) Determine the final temperature,    $^{\circ}\,C$
(b) estimate the total change in entropy.    $J/K$

  (a) What is the coefficient of performance of an id bfr*:xf33 kbceal heat pump that extracts heat from b*xfbk r :cf336$^{\circ}\,C$ 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 releases abous mtrsgng l*e7tt o-hj-;.6z(dv c+s.t $ 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 operati8kjao++n 7g11 z8nigbq(bnr yng 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 frooz9a zulsipry;f; : 6jsm+(;am state A to state C in Fig. 15–28 for each of the foz9r6 p:s ofjaz +u;ial;y( ms;llowing processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical povmvm(dwrlhe 1a(2c,* v dafsk4w51; hwer. Cooling towers are used to 2 vawkddslh(1*hfm4vm(;cewa5 ,vr1 take away 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 using steam turbs lg0 hc*d5dy2ihy(;bines. The steam goes into the *( c0hb5syh2d;gy ldi turbines superheated at 625 K and deposits its 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 xv.en), 0sif.t*x( yxrvip v 5oco; y0about 15% efficiency. Assume the engine’s water temperrvxx*fx,v0 ip . os;i5cvy. 0y)eto n(ature of 85$^{\circ}\,C$ is its cold-temperature (exhaust) reservoir and 495$^{\circ}\,C$ is its thermal “intake” temperature (the temperature of the exploding gas–air mixture).
(a) What is the ratio of its efficiency relative to its maximum possible (Carnot) efficiency?    %
(b) Estimate how much power (in watts) goes into moving the car, and how much heat, in joules and in kcal, is exhausted to the air in 1.0 h.P =    W $Q_L$ =    $ \times10^{ 9}J$ $Q_L$ =    $ \times10^{5 }kcal$

  An ideal gas is placed in a tall cylindrical jar of3: whh44phyid 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 resukafy1 001z*s-pk jj jslts in about $ 3.7\times10^{7 }J$ of internal energy in the body.
(a) In one day, how much fat does the body burn to maintain the body temperature of a person staying in bed and metabolizing at an average rate of 95 W? $\approx$ =    $kg/d$(retain two decimal places)
(b) How long would it take to burn 1.0-kg of fat this way assuming there is no food intake?    d

  An ideal air conditioner keeps the temperature inside a *rj-dec+j;ic i k q93l 9 vq8rwjrs,s7room 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 doymg8d(8jxj lo ,,:ivk*xp +mvor.” 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 jmm*xo(+8p, x g: jk8il,d vyvway 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