What happens to the internal energy of water vapor in the air that condens9jlc p:wy-oy 1es on the outside of a cold glass of water? Is work done or heat exchanged? Explai o-wyc9y1l:pj n.

Use the conservation of energy to explayqs+jpt rn3* ;in why the temperature of a gas increases when it is quickly c;j*r3spyt qn+ ompressed — say, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by an i cr/:wx;ky21hbkbbm by 29 e6gdeal gas. Is this enough information to tell how much heat has been added to tx;bb1e 2b2 c6/ykgkh:m ywbr9he system? If so, how much?

Is it possible for the temperature of a system to remain const,m c voii8t8a b13.f(a(awggtant even though heat flows into or out of it? If so, give one or m(cit, w vta( a818iabgg. fo3two examples.

Explain why the temperaxkh ui-v 8y;e1ture of a gas increases when it is adiabatically compressey1-i;v8xuh k ed.

Can mechanical energy ever be transformed completely into heat or internal ek8+t 7q.wnsuznergy? Can the reverse happen? In each w7 +8.qntuzsk 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 oven doorwt.w dwtd;u 68 open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door o68tudwt ;dw w.pen? Explain.

Would a definition of heat enginez7 3p; jz7syb :.gfncq4c1giu efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperatur )7g,gac9rgzje areas in (a) an internal combustion enginzg9jgg ) car,7e, and (b) a steam engine?

Which will give the greac- (bqzqf4ch/s ; jmzb8h9rzb0n g:1vter improvement in the efficiency of a Carnot engine, a 10 zjh zb0mn vbrz/;h 4(qcc8s:1bq -fg9$C^{\circ }$ 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 (interj, lgntu *db*xurj/0fg ay+5:nal) energy. Why, in general, ia+n:dlbjyguu*gx f5* j ,tr/0s it not possible to put this energy to useful work?

A gas is allowed to expand yo,rz*lp de8 tfop91b56 rl4 g(a) adiabatically and (b) isothermally. In each process, does the entropy increase, decrease, or stay thf 64ryl oge9 pzl5pd*r8o,1 bte same? Explain.

A gas can expand to twice its original volume either adiabaticaf3wn:kr6fb1 s-q l c:xlly or isothermally. Whichf6:bq3x nw :s-frlkc 1 process would result in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of naturallf0 +(rpb n2vsby occurring proces(+bbr20n spvf ses in which order goes to disorder. Discuss the observability of the reverse process.

Which do you think has ula51a6dr0 haba7 6p-3l* hhi l2 itcrthe greater entropy, 1 kg of solid iron or 1 kg of liquid iron? Wah- auatr26c5l06*3 l1 h 7dpihla rbihy?

(a) What happens if you remove the lid o2qph+n6 g6 bxgf a bottle containing chlorine gas? (b) Does the reverse procesgb6ph+ng x q26s ever happen? Why or why not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls anq l8 h+d /q7 jjk ;8,g7rucs)029oalnrn prjzd “in-room air conditioner”: gac l87h/02oj d9j)lqu nd+,q pr8znr r7kjs ;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 this machine cannot cool the room?

Think up several procd -hg7q qm;d8q 3i.w-x dfvxra sh8j66esses (other than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occuq8j-8hfaxis gv 7wx.dq66 -ddhq; rm 3rred, would violate the second law.

Suppose a lot of papers are strewn all over the floor; then b 5n lk)qmg98ukwh./tyou stack them neatly. Does this violate the second law of thermodynamich5k8k9tnmw )qlu bg./s? Explain.

The first law of thermodynamics is sometimes whimua le(:5 rw9ibdb 1i,esically stated as, “You can’t get something for nothing,” and the second law as, “Youi,5iuw1 e d9b lr:ea(b 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 tells us in which direction nt c)uel0e6 )y:.plckxatural processes occur. Ifup6)lx kc0. :ytcle )e a movie were run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, conbqh:me.n wx+k *fi /.hy d,sp-vert relatively simple food molecules into a complex structure. Is this a violation of the secondqbdi:ek.f, .nm-yw+ /shxph * law of thermodynamics?

  An ideal gas expands isothermally, k y7vh8z/ rtowg-pb;/ performing $3.40\times {10}^{3}J$ 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 fitted with a light frictc(btm da*i4qo-y9rb/qw1ay / ionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is a*ayrqq 9i1 bat4od(my b-/wc/ dded 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 .   $\times {10}^5$
(b) the change in internal energy of the gas.    $\times {10}^6$

One liter of air is cooled at constant pressure until8 kuhthr3cf4q )5jyl 8*r 9wdq its volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw r4q y)9h8h38cl *f5 j ruwktdqthe process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas at n//u3n alz)gpj99 mai atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the original pressure isa9 9pljamg)//nin 3u z reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is allowed fo ygnu:)l:w.bjf ;9vu6gw ) vx-h*mjto expand isothermag:)j ff6lb y 9*w.v)-hunu:gxwj;vom lly 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 for the axes.

  The pressure in an ideal gas ieyu6rx k -8bm)s cut in half slowly, while being kept in a container with rigid walls. In the process, 265 kJ of heat left tem)uk by rx6-8he 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 4 mwl9+xdce2 sis compressed adiabatically to half its volume. In doing so, 1850 J+lm9ex 24csdw 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 fromq*vrl8h7i rjw f.y w-fr2go:2 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressq.y:27hvo -jf8 iww l f2rrr*gure 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 /r j)zq;32 qev x.crfz dsl81x1vexi*of an ideal monatomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the gas durin 1idx; fe*1).qx zql 3vzej/cr82 vsxrg this expansion?   $K$

  Consider the following two-step process. Heat i--eyx rh(rcf ,tsno;7s 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 e-;t,7 rf(-yoc n hxrsexpands 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 possid-b-q4 4 zmoqiunsx*4ble states of a system containing 1.35 moles of a monatomic ideal gaqni d4u4 b-o*mz-sq4x s.$(P_1=P_2=455N/m^2,V_1=2.00m^3,V_2=8.00m^3)$
(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 along the curved path 2a7q/33ocfejismnr , in Fig. 15–24, the work done b 7s,oeimq /23afnrjc3y the gas 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 state c along the curved /y kanahe89j l,f0c:c path shoay9e0:k,jnf8/l c hacwn 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 $U_a-U_b=10J$ 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 transform if instead of wor/ *xbkvda(pkmm- 8 hl1king kpv1- ha xl/(mb*d8 mk11.0 h she took a noontime break and ran for 1.0 h?    $\times {10}^{7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sits at a d49 we nah(b, xjljv5xz0dmo*x2;s:j iesk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h,iezw0,;n b:o9xls24j(vhjm x ax*j5d plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose6mjm ;cromb ;wnt2p9( weight 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, as c6mj;2 pmm t;b9(nwrosuming no change in food intake? Assume that 1 kg of fat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while performing 3200 J 7 k5cb6ej :uc-mw 6csd)gx*vbof useful work. What is the ev )b u5-xb sgcc6mje:6*wcdk7fficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 k omm;h/v8;vvi 8li, vccal of heat from a high-temperature reservoir. ;m8l/;8oci,i vm h vvvWhat is the efficiency of this engine?    %

  What is the maximum efficiency of a heat9.dvrn--y3/ uf/k5 m ffpljfe engine whose operating temperatures are 5805fy ek9d3jn-uf.rp /lmv/ ff- ${}^{\circ }C$ and 380${}^{\circ }C$?   %

  The exhaust temperature of a hea-))-c hmjwk hmt 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 maximu/9,uhclc-d: b -qq m ptit6dl1m theoretical (Carnot) efficiency between temperatures of -h- q i/qcllt1d p:,um6t9d cb625${}^{\circ }C$ 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 environment be hoa8 + rk 3z5)qs(eolwaptter 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 transferrezrk )soqpweaa5l 3+8(d 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 while using jyribx)f uzi):6ol6 - 680 kcal of heat jiboily-)f x6:u)rz6 per second. If the temperature of the heat source is 570${}^{\circ }C$, at what temperature is the waste heat exhausted?    ${}^{\circ }C$

  A Carnot engine’s operating temperaturey: vz(tlq0f 9ms 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. Estimate the hev(0bjh3jyl -n(u zw*aat discharged per second, assuming that the plant has an efficiency of y*-jwvn( (b lzu3a0jh 38%.    $MW$

  A heat engine utilizes a he4 wmbk.q(+jjorhio:5at 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 exhaustp 81qsav,dyhi-x x6-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 pairs, the oukusykd-qcv a+fi. k, 7vz:1u8tput of heat from one being the approximate heat input of the second. The operating temperatures 781c+:sia,ufvk kq. kuv ydz -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 coolca *xfe e-.w1cjqi+(v ing 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 operatau3qzc4 i6lg:0am z /hvypu5-es with a in a 24${}^{\circ }C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of c :bc wt9,y mzbdzj; wd:f;(4e5.0. If the temperature in the kitchen outside the refriger , t;b::cbcy(;9wdzwf4 djme zator 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 housn*;h;kz:ds8cbd l 9sde 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 atr oq/y:p6 lcor0g6 -fto6k1o r 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 has6q*83 /i h4s rv0inix 2lspkhc an efficiency of 35%. If it were possible to run it backward as a heat pump, what would be itpn8k4 0/2i s6hhrvq3ilsxc i*s coefficient of performance?   

  What is the change in entropy of 250 g of s zmha pn9 vowila(+;1:team at 100${}^{\circ }C$ when it is condensed to water at 100${}^{\circ }C$?    $J/K$

  One kilogram of water is heated froueyd* l9 yma 1yf3.l5 -g ;y78cvvoaljm 0${}^{\circ }C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entroqd w7da )c3te6py of $1m^3$ 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 i)hugwt/f *neawp7*g/ nitial 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 kineticrh(up*ca c-;g energy KE just before striking the ground and coming to rest. What is thc *r(gaph-;u ce total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod cond; arox 92s(txbucts $7.50cal/s$ 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 30 imnl- fom06*lx0 -emrydz/dps gt *1(${}^{\circ }C$ 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 at p)4/bnra s,ii30${}^{\circ }C$ 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 produces ,mdazqh d: tils4fdm ,9*n4a r.g-a z7550 J of work per cycle for a heata:dgimd.z, hzdq*-,f t l7amns49r 4 a 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 dix wl t.v qi21r.1j(y;ly/ gshcce, 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 imr *u//h n/rdin 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 no two equal-value cards. Discuss your ranking in terms of microstates and macrost* r //umn/dhirates.

  Suppose that you repeatedl if 95i1cludp,y shake 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 tdlfpi, i1u9c5he 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 elex/t71 g0mu pmg6 a2lnkdr+r/ rctricity per square meter of surface area if directly facing the Sun. How large an area is required 6+2r1x/ nd tgum/gr7k0alprm 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 i b)e :qdf3:dffor use during peak demand by pumping water to a high reservoir when demand is low and then releasing q:f :d3ebi)fdit 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 created by a dam (Fig. p mwg3xif(cc ng+d80.15–27). The water depth isfi cd8g+ w0ng(cx3p .m 45 m 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?    $\times {10}^{7}W$

  An inventor claims to have designed and built an enginept()p,sady 4p c,kor 1 that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecto)p,psycdk,tpra (41ing 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 engine has an efficiency of 0.25 and delivers 220 +q3.a twfafx6 J of work per cycle per cylinder. When the engine fires at 45.a awx+63qftf cycles 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 (the reverse of a Carnot engine)/vis/ x41l ugdn fu8m 4cc6mt8mh2jr. absorbs heat from the fre.lnd4/gvcrmsmf1u cm th288 j6i4 /xu ezer 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${}^{\circ }C$    $\times {10}^{4}J$
(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 develope nw /e(ljyhfqk/*;asfq4 pv (3;teo*zd that made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatuvfsfekhj *z qtq/wan;pl3* e;o/ ((4yres 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 directi 0b9a wr43rdgi kremoe6.,2rxons when they collide and are brought to rest. Estie9.i 6rdx3a4kr gbmr,2e 0 rwomate the change in entropy of the universe as a result of this collision. Assume $T={20}^{\circ }C$    $J/K$

  A 120-g insulated alum ));a pjhlckxey5q6 t4inum cup 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 coefficient83mabn6 hb dp(we6 f5xu;/bac of performance of an ideal heat pump that extracts heat ;fe5p3awua6/x(c8bdmh 6 nb b 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?    $\times {10}^{7}J$

  The burning of gasoline in ac mxf l/ykq:bhw wq,c.(y-+fc j5 m0-e car 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 lower operating tempera,imf 8u4 x+hgwture $T_L={20}^{\circ }C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal gas in going from state sy+nhy, 5xn4e 4mvh7r A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC dir+44n 5ry, hxsvh mny7eectly.

  A 33% efficient power plant puts out 850 MW of eri2*/eqlqapd 8 t)4lylectrical power. Cooling towers are used to take away the eidqp rql2/ *a84e)ty lxhaust 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 planu1asv2i c/wrtx j6 o59t delivers energy at 980 MW using 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 iduv5scw xijar 6/192o teal 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 ab1nw b; r71ut h q6ugu)65xhlpwout 15% efficiency. Assume the engine’s water temperature o buqtp ulux5 wg61 h;7)6whnr1f 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-sectional area 3w2ej73 jc9.)g27eu qulsyhy ws;gx z$0.800m^2$ A frictionless 0.10-kg movable piston is placed vertically into the jar such that the piston’s weight is supported by the gas pressure in the jar. When the gas is heated (at constant pressure) from 25${}^{\circ }C$ to 55${}^{\circ }C$, the piston rises 1.0 cm. How much heat was required for this process? Assume atmospheric pressure outside.    $J$

  Metabolizing 1.0 kg of fat results in etjf*qm, 5p; (f(f qn*tt9 .fvi jlk0tabout $3.7\times {10}^{7}J$ 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 insdw +58+) tpe x-cfo /ogi-ncdzide 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.” The h:.v;*-bc eu-z xfsyn wumid air is pulled in by a fan and guided to a cold coil, where the temperature is less than the dew point, and some of the air’s water condenses. After this water is extracted, the air is warmed back to its original temperature and sent into the room. In a well-designed dehumidifier, the heat is exchanged between the incoming and outgoing air. This way the heat that is removed by the refrigerator coil mostly comes from the condensation of water vapor to liquid. Estiszc*bv:.ne - w- xyu;fmate 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