What happens to the internal energy of water vapor in the air that condenses on, tams4p1dyg 3.ybrw6 the outsi3rydbtm,g1s46 p ya.w de of a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain why the temperature of a gas incrwsn q3-p6 ,y9 ys0giwceases when it is quickly compresseyg scy6 wsi0w9,n-pq3 d — say, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of +m64 )w7ge okjqjba4g work is done by an ideal gas. Is this enough information 4gakjo4+ ) 7qw jgebm6to tell how much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system to remain consy6jba i1ax8s*tant even though heat fl*61ixajsya8 bows into or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiabatically compresscah em:heg0o45xj)e64dixs-a l 2d2 led.:2eca4de hsa4g2dij-6o) l ex hl0m 5x

Can mechanical energy ever be tr(vacwej,3x/ b .vf,qwansformed completely into heat or internal energy? Can the reverse happen? In each case, if your,3v ,xawv qjcef /(.bw answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven door opeva)*/zvl a;5ibigof +n? Can you cool the kitcheni+ab/ g5oi *fav);z lv on a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of heat engine une).6 oigh 2 h/h3zxqefficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperatureah9*cgy: v (yb:fv-(wxj7 yvj areas in (a) an internal combustion engine, and (b) a steam engyj bcy7hj -vy*ax9:(:gvf v (wine?

Which will give the greater improvement in the efficiency of a Carnot engine, a r(ag --7 bfvbg10 bva-rgg f(b7-$C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous am0 zy) pm4xv4rzq2 imige4cb;, ount of thermal (internal) energy. Why, in general, is it not possible to put this energy to mvzi4p,i0z4ge x)c 4y;rqbm2 useful work?

A gas is allowed to expand (a) adiabatically and (b) isothermally. In each pro *rqt5 c yj*7ul2 1xi4rr3hcqkcess, does the entropy increase, decrease, or sta4*h* rrrtq 3cc2uqk7lyix15j y the same? Explain.

A gas can expand to twice its original vo pjx-9,m1irwy*l jzd3 zbci 0w6a2 t2qlume either adiabatically or isothermally. Which process would result in a g9p* xw3mj22w6 tbdzlz0 - ajiy qc,1irreater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of naturally)nvcv 1w: rj:.. gsidu occurring processes in which order goes to disorder. Discuss the observability of the reve1.g vi.sd:ur) wcjv :nrse process.

Which do you think has the greater entropy, 1 kg of solid iro)w twb w(m/fovw7 cm(u8cfh 6*n or 1 kg of liquid iron? Why*cmw7 t/( wvuhfw8wof)mc( b6?

(a) What happens if you remove the lid of a bottle containing chlorine gas? (b)z+qx4 dh;( w0pg r-yru Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples of irreversibilityq z ;(pxg4hr u+-ryd0w?

You are asked to test a machine that the inventor calls an “in-room aik2 sbw/8v yys,1fu;b,dy rh3 a k*fg+ar conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine /2w+f d ag,;r* k ys1skay,8fvb3buhyis 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 alresa1vg6 zu- (g7uz 0pjsady mentioned) that would obey the first law of thermodynamics, but, ifz70j-a6 1 pv usuggs(z they actually occurred, would violate the second law.

Suppose a lot of papers are strdovb6g n+bcpblh:15m ,q o01 dewn all over the floor; then you stack them neatly. D o1:d,o 1l6c+05 vmbqngbdpbh oes this violate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stated a1poz /s2* ;4qbk tkgqc rsw;*ns, “You can’t get something 1tcgnkbpz;*sk*4q q so;w r/2for 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 tells us in which direvh40wbqnaeq.) q5y3 ,p: d sthction natural processes occur. If a movie were run backward, name some proce5v. :nhq)ytw,b a4ph0d3 qqsesses that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, cohm ho p5c9r 9id:hhrv s-i)5+pnvert relatively simple food molecules into a compli h ro5vc9mprh-h +5)pds :ih9ex structure. Is this a violation of the second law of thermodynamics?

  An ideal gas expands ig tyitf9-4b h zqui2..sothermally, 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 and2 a tre(az)l4k maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, t4zk)(2tra laehe volume is observed to increase slowly from $12m^3$ to $18.2m^3$ Calculate
(a) the work done by the gas .   $ \times10^{5 }$
(b) the change in internal energy of the gas.    $ \times10^{ 6}$

One liter of air is cooled at constant press co: kw8y2 2fd:wskzdfds-uj*w t:f0 *ure until its volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the process on a PV diagrau-jwk s:2tf*f cydskd2wf :8 *wodz0: m.

Sketch a PV diagram of the following p;vy;;pq4okwis)mv fna,rm q,5 f.nn .rocess: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressurev;;)mvnffkpo.5q4 ;mq rn,, iw yns. a 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 (abs6ulwb39f vph s pau1jc/.)/ sbolute) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume9. bhs jl/sp u/)cb6fw3puv1 a, and lastly is brought back to its original pressure by heating at constant volume. Draw the process on a PV diagram, including numbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while being kept in a cont92i qs/9rgapediri /17v/d ovainer with rigid walls. In 97vv//rai/ ddrsg1eii2q p 9othe process, 265 kJ of heat left the gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas is compressed adiabatically to hdi4cseut a5 n 0*m/sg/alf its volume. In doing so, 1850 J of work is done on the gasu ea/i0c4mstgd5s* / n.
(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 ncm1 f ((vv.ic3cp1n d400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the f cdn(cn3.(cmvp11 iv pressure and temperature are allowed to drop until the temperature reaches its original value. Calculate
(a) the total work done by the gas in the process,   $J$
(b) the total heat flow into the gas.    $J$

  One and one-half moles of an ideal monatomic gas expand adiabatically, pu05m v5agsc*6ssqv;ct ii1u v2m: jd3erforming 7500 J of work in the process. What is the change in temperatu0im cv;*s:smvuiad31c652u 5v tg sqjre of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is alloweqw2lkhfwx4g*:ss7c6p 1z5 rtd to flow out of an ideal gas at constant volume so that its presqwp4x*2lht 7s1wsr 5kf gz6:csure 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 egoq3mnfvt::0; y ax0v :sle7 two possible states of a system containing 1.35 moles of a monatomic mtv0so :7 :lf:gv0 enyqx;a3e ideal gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to c along the curved path in Fig. 15–24,n htwp:b - k4p1fqn)qa1yc/ a; the work done by then ;tay 1 nqf:4wq/c )1bahkpp- 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 along the curved path shom kp fu.jp a92s5,zc5iwn in Fig. 15–24, 80 J of heat leaves the system and 55 J of work izpk i5.2js c5afpm,9us 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 pers 29p phthfyx/1ss q9zt .d7,adon of Example 15–8 transform if instead of working 11.0 h she took a noontime break and ran forqd ,txhp91ps9/7tzf2sh a. dy 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sitanefqa2kj9g4 1r 6ha :s at a desk 8.0 h, engages in light actihn:6 akfea a91qjrg42vity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per day, using the 2;fs5 e)b0q9t,hh v1ohqs kxh time for light activity. Howq02kxhob19e ;)fsqs5h hhv,t 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 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J oygv 6v)7sh 7k l+a8ei:uq*c1sete-)mf od;p r f heat while performing 3200 J of useful work. What is the efficiency of this engi;m)e8vr pk sit76a+7 :e huqgcsd-1el *o)yv fne?    %

  A heat engine does 9200 J of work p h.yi,tu b.hl;er cycle while absorbing 22.0 kcal of heat from a hig.l.;ybt,hh ui h-temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operati.o nq4ekd,o:89 exfug ng temperatures are 58,.xn 4 ke8q:of9d euog0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine5cmz(yr g 8bq7e.q xk. is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant g,2ici7ydc:i) yqz w5operates at 75% of its maximum theoretical (Carnot) efficiency between temperatures of gi c)i,w5z2 ydqc7i:y 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 environment be hotter than ambient 9bu-/ ohe;jbxz.zs t 4awb k+;la /k:ytemperature. 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 e u okba b :hxt-/bl9sz/y 4zwk;a;.j+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 419 b 0 fhvvae +ng c8afvm80u*:7gxoyj40 kW while using 680 kcal of heat per second. If the temperature 88c9y mb +0 *vn vhoau:7ff0 egjax1vgof the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temper yko6/4i7s4zmny u 2etatures 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 Msj4olcd3 2rleq2 p*k4t3njr8 W of electric power. Estimate the heat discharged per second, a43rrn deq2 lkjt*c23pjo 48slssuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source 1ow4ilmj 6 t p ;n4yy5wgq*t5bat 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 its he;0ryf +xeaz4p at 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 pair(5l(op .hy 3m/dymq bzs, the output of heat from one being the approximate heat input of the second. The operatingqy3/hz .y5((obp mlmd 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 css6sype5 xg4j5j+. w uooling 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 h:dwmcm6yl 8 d0 x3) ,qfivz9wa 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of wjxmk -ploz4e. qt9-1performance of 5.0. If the temperature in the kitchen outside the refrigerator is 2jezlp.- x-t14wq o9 mk9$^{\circ}\,C$, 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 at yk+- olr9e ur722$^{\circ}\,C$. 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 waterwxu897ccz rf+s0e)0elji0jw.v8a zbbjo 4a3 at 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 35%. If it were possible to run l*kzil k*ge9-o )*rhasx5z: mit backward as a heat pump, what would be its coefficient of performance? 5x*zi-lha mk:*9)rlseo *kzg   

  What is the change in entropy of 250 g of steam z.a)flo8lt; 2zema /lat 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heated fro6ce7w k9 hk8utm 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change i;j hj b.:81xzn8 tcpwrn entropy of $1\,m^3$ of water at 0$^{\circ}\,C$ when it is frozen to ice at 0$^{\circ}\,C$?   $ \times10^{6 }\, J/K $

  If $1.00\,m^3$ of water at 0$^{\circ}\,C$ is frozen and cooled to -10$^{\circ}\,C$ by being in contact with a great deal of ice at -10$^{\circ}\,C$ what would be the total change in entropy of the process?   $J/K$

  A 10.0-kg box having an initial speed of xc.zr hqaf(zpu d*58a(an2 i +$3.0m/s$ 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 befo5vp:nigjv4gng fddsz0m l r9 87y 627ire striking the ground and coming to restmr vl25ifg6n di:zgvjds y4p77 g890n. What is the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conduc3)e3wz fv +j8 wc7ixllts $7.50\,cal/s$ 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 308: r wnn obv1hyp.+4qo$^{\circ}\,C$ 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 alumw4zyic)sa( ,7d 3 xnuqinum at 30$^{\circ}\,C$ is placed in 1.0 kg of water in a Styrofoam container at room temperature (20$^{\circ}\,C$). Calculate the approximate net change in entropy of the system.    $J/K$

  A real heat engine working between heat reservoirs at 970 K and 650 K producec .bb9iz(mj5)4j jfmy s 550 J of.mb9jj() ib5fcz4yj m 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 dice, of obtaio)w-w tuli,o -c(evo3ning
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hands in order of increa w0r mywl/4q8ojuq x9bgob0( )ux 5c2xsing 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 eu2) 5/wbyj98bx x0wo4 g0c( l uqromqxqual-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand andb fd7a 0rr19dq drop them on the floor. Construct a table showing the number of microstates that corresp1dqrd7 f90abrond 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)4:j c,;+zhdfyigl y/o d+ )sgu can produce about 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is required to supdu f,yjc h ggy: +ds4;)o/zl+iply 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 i 4 hldzyf29 k1blrs,h)tr/1i for use during peak demand by pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumped to a lake 135 m above the turbines ath hlisyrfz/9rki, b2)14dt1 l 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 a dam (Fig. 15–27). The water9ns 9z80o +mhnm)hjh r(ql7bg depth is 45 m at the dam, and 9hj zmm0 )lhnosbhrn87g(+q 9 a steady flow rate of $35m^3/s$ is maintained through hydroelectric turbines installed near the base of the dam. How much electrical power can be produced?    $ \times10^{7 }W$

  An inventor claims to have designed9q(jfxj-92+dv+hs vpnlz u3*t6a uq2uclv 8t and built an engine that produces 1.50 MW of usable work wh+c-u uj6 htlql89xv d2 z92u(qjvsvf3*a ntp+ile 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\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 s;d(xt;, f wbtdelivers 220 J of wor,t (fbdt ;;swxk per cycle per cylinder. When the engine fires at 45 cycles per second,
(a) what is the work done per second?    $ \times10^{4 }J/s$
(b) What is the total heat input per second from the fuel?    $ \times10^{5 }J/s$
(c) If the energy content of gasoline is 35 MJ per liter, how long does one liter last?    s

  A “Carnot” refrigerator (the reverse of a Carnot engg4 1qm+aw.: hz-aegrog,no 9gine) absorbs heat from the freezer compartm: q-zen mggo4hg., a ro91ag+went 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 t)cy;a.x9juwm)gyg 9y hat a heat engine could be developed that made use of the temperature difference between water at the su ;yj uy)gwya.gm9)xc9 rface 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 dir1jeqxqo h3h-/ections when they collide and are brought to rest. Estimate the change in qh x/ejo-31h qentropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup:a1d:ci mudqezxap9 67)kcwo0d:q o+ 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 perew vmbs5 6ttq-h(1 9mgformance of an ideal heat pump that extracts het5m1(qvmws-6tb ge h9 at 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 x 3ec:0f54y fpvit sf4car releases 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 a9* s9h n moa.trsf ;zzryk 2 -rkoxe5y6tr(1,s lower 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 idebdtiq +3ca-ndsarp.q17:ux. al gas in going from state A to state C in Fig. 15–28 for each of tqd71p+.na -x ds:tacui 3rb.qhe following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MWbm 0tddhkm /3cc 6hy/3 of electrical power. Cooling towers are used to take away thek md3y/c0bh6cmht 3d/ 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 ener9 wbhm 1r* 4 6bg7hg3l+j.ygtkzu fho)gy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heatut*o9l3f h w 6b 7jg mgybk1zh)+.rhg4 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 about 15% effickr a-4/5 -zise3bok -u fqifk+iency. Assume the engine’s water temperature i3s 5koqz+u4 b/- irf-e-kfkaof 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 of cross-sectional agcirsrwq-+)5dvxv;b fd-,z 7h o(3xf ig, o1erea $0.800m^2$ 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 res-7ao; -*eb//gds fov8elo/gdp 4 xpaiults 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 temperat+ 5u*byep oao:ure 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.” Th: idds0 d:,ukle 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 from the condensation of water vapor to liquid. Estimate how much water is removed in 1.0udkis :0dd ,l: 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