What happens to the internal energy of water vapor in the air that ce y4 .tw1 pwi ohicj890gl4*il dnsd-3ondenses on the oje ps4n43og i1l.wi hicytld 80- w*9dutside of a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain why the temperf xh im )ffl5l0v+q-q+ature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temper- +hq0ilf)5vqfflmx +ature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by an ideal vac9 av js;5- yabbk2;gas. Is this enough information to tell how much heat has been added to the system? If s-a;y2sc5a;v9bj abvk o, how much?

Is it possible for the temperature of a system to remain co6kurrrdmv79 y4z:e r/u7u- ta*r sp8qnstant even though heat r9u7r /v k46*:pt-mreaz7y druurq s8flows into or out of it? If so, give one or two examples.

Explain why the temperature of a gas increase m zi8k5aau45as when it is adiabatically compressed4mk58iaazu 5 a.

Can mechanical energy ever be transforme2p+( 3xdl30m hkoj gg0h7 pa*m6ocy ted completely into heat or internal energy? Can the reverse happen? In e j*mgc k3 x30p76ahm0edol2h+gp(yto ach 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 dl- zoa81lf05s/ u b3pqd*xmudoor open? Can you cool the kitchen on a hot summer day by leaving the refr xdfa5q3* -po0b 8umls1/z udligerator door open? Explain.

Would a definition of heat engine efficiency 8k6w2i hh(q k65ght uvas $e=W/Q_L$ be useful? Explain.

What plays the role of hig;f+;n v2- zt/cpqswt5 h0eddo h-temperature and low-temperature areas in (a) an internal combustion e w 5qo2;v ents+chd/0 tf-;zpdngine, and (b) a steam engine?

Which will give the greater improvement in the ef :wb v5:r*fpqfig/ 6hnficiency of a Carnot engine, a pf hb*grv 5:qfw ni/:610 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a treme: pnc0or7w8e7g :uk mgndous amount of thermal (internal) energy. Why, in general, is 7er7m gnwk8cu::o0gp it not possible to put this energy to useful work?

A gas is allowed to expand (a) adiabatically nvgb en 8/a7b+and (b) isothermally. In each process, does the entropy increaagvbn 8+b/ ne7se, decrease, or stay the same? Explain.

A gas can expand to twice 4l ne 97.t0)m qfodkhfits original volume either adiabatically or isothermally. Which process w9fdqt.)n l7ehfko 0m4ould result in a greater change in entropy? Explain.

Give three examples, other than those mentioned iy zm0lt,lwtz83- ; b*we09*mq9 ixn:ca kawnyn this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the observabilabm lix30knew m8lca*:wzq-w9yt0n, ; 9 yzt*ity of the reverse process.

Which do you think has the greater entrop8wno,1a.wi n z eeh;o*y, 1 kg of solid iron or 1 kg of liquid iron? Wwhon8i; az.*,eoe1w nhy?

(a) What happens if you remove the lid of a bottle containing chlorxef35agtm 3 o;ine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples of irreversibi a5 e3;fgmoxt3lity?

You are asked to test a machine that the inventor calls an “in-room airqkho hy+ y;*bcd0 -o0y conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel;0q0ykyo h+hbyod -c* 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 alreadotx-- tq-mwl- y mentioned) that would obey the first law of thermodynamics, but, iflx-- otm- qw-t they actually occurred, would violate the second law.

Suppose a lot of papers are sr 3dli ,tly kccj0;0e4trewn all over the floor; then you stack them neatly. Does th 0j3il ccdt;r k04,lyeis violate the second law of thermodynamics? Explain.

The first law of therm(so 9m aty0*jpzx4a i*odynamics is sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Expl4(j0a** otiszxpa 9ym ain how these statements could be equivalent to the formal statements.

Entropy is often called5w:;o (ktvu pr “time’s arrow” because it tells us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that woutp(:wov 5; ukrld tell you that time was “running backward.”

Living organisms, as they grow, convet4i+ba2 xl)kdrt relatively simple food molecules into a complex structure. Is this a violation of the second law 2d+ xabkl )t4iof thermodynamics?

  An ideal gas expands isothermally,yk3fh-3;pi7yq9v ddt 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 +yvps8laml+g(g(j.m fitted with a light frictionless piston and maintained at atmosphericsgmjvl(mg p .+ yl8+(a pressure. When 1400 kcal of heat is added 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 .   $ \times10^{5 }$
(b) the change in internal energy of the gas.    $ \times10^{ 6}$

One liter of air is cooled at constant pressure until its volumvkja,4/5r c zp 0r5ml/bmp/ qaw pa*4he is halved, and then it is allowed to expand isothermally back to / bz p4ap c5*r5rwpvm aq/kajm ,hl0/4its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following lmkk o,gwb (2a;dui0 .zn(m:r:bn, mx process: 2.0 L of ideal gas at atmospheric p ( 0:uwm;.aid2k xornbb,g(ml zkm,n :ressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the original pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolutvir h*qdp 1h36e) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, a vrdp q6*13hihnd 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 duao5 xr.l1c1t zlk ; g.e5pp+cut in half slowly, while being kept in a container with rigid walls. In the process, 265 kJ of heat left the gasdc.pu rtl;xa+l115oe5kpzg . .
(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 half i b8(e5lh tr0 q5tmwp2p,l1zjdtgqm3: ts volume. In p5 b gmd2 :jqhrl8 tw,z50l(emttp31qdoing so, 1850 J of work is done on the gas.
(a) How much heat flows into or out of the gas?    $J$
(b) What is the change in internal energy of the gas?    $J$
(c) Does its temperature rise or fall? ----待选择----fallrise 

  An ideal gas expands at a cons/y+z(vme3gihc xtq-0tant 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 allowed to drop until the temperature r y+3xtei -(0ghmc z/vqeaches 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 of4 . oyzc56ub )5igpqhk an ideal monatomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the gas during this expai cy6h5zk)uogp b.q54nsion?   $ K$

  Consider the following two-step process. Heat is allowed to flow -c,: ughy*fsrl.v m6xout 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 temperature reaches its original value. See f : ,.h gmrvs6cu*yl-xFig. 15–22. Calculate
(a) the total work done by the gas in the process,    $J$
(b) the change in internal energy of the gas in the process,    $J$
(c) the total heat flow into or out of the gas.    $J$  ----待选择----intoout  the gas

  The PV diagram in Fig. 15–23 shows two possible states of rcr5l 5w.r) 0b;sos2 mvdwts:,f d5fza system containing 1.35 rzbd.rso 5 2c;mfw)rwd ,:vt 55sfl s0moles of a monatomic ideal gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from5lxfq5kamwy58 9ya.*u qi 0ltz;n nl- a to c along the curved path in Fig. 15–24, the work done by the 9u k;-8yl*aq ilml.wzyqnnt 55xf 0a5 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 shodh:3 s+is . 1tjvcswv2wn in Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on vh c 3ij.ssw1+2v :stdthe 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 instead of wo )m3iuqc82q,t + mkccxrking 11.0 h she took a noontime break and ran q x8m+ qct 3,iukmc)2cfor 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h,x 3k(,; 0*h6/ibwq vegrvqheq sits at a desk 8.0vq ex*6v0qr q3,h;/hk( bigw e h, engages in light activity 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, us0b2z .rxeo97hbquv 4r58 gyjting the time for light activity. How much weight (or mass) can this peruetg5jb z0o 2b r8 q7yr4hxv.9son 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 exhaus 558i a6+)suk0h dywgot jdag1ts 8200 J of heat while performing 3200 J of useful work. What is the efficiency of this ewo6a )us8g y0i 1htdj5+5gdak ngine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0.k)clwc4b :f bau+ 19)rpnx yg 8xtx8u kcal of heat from a high-temper g8kntbfxux ubr 8 py9c+ .)4)xl1cw:aature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a 0mp 5s o/rj-bm+ yiga*heat engine whose operating temperatures aresy/roibp* m0gj+ m5 -a 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engixvin3cu (ys ;k,,)w zjne is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plan9 *jahnkhyz p /4lhi.6t operates at 75% of its maximum theoretical (Carnot) efficiency betweea4*lz hi j.hkphy9/n6n temperatures of 625$^{\circ}\,C$ and 350$^{\circ}\,C$. If the plant produces electric energy at the rate of 1.3 GW, how much exhaust heat is discharged per hour?    $ \times10^{13 }J/h$

  It is not necessary that a heat engine’s hot environment be hotter thanb *l4 b1dhvklfp*p+e) k.n:ws 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 4lkb)1*pk:eb +s* ld vnwhp.f(293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at j2r5: :tcl tfxthe rate of 440 kW while using 680 kcal of heat per second. If the tempe rctjxf: t2:5lrature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temp;1hg s ) o0lwmup3d8oiehtd 2/eratures 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 powe9c n7zhol k2n*0lxoj ks2o5/ hr. Estimate the heat discharged per second, assuming that the plant has c2nk0o *ox5 7lozn 2s 9hj/hlkan efficiency of 38%.    $MW$

  A heat engine utilizes a heat 02rznd:lo qnjj /g- h.source at 550$^{\circ}\,C$ and has an ideal (Carnot) efficiency of 28%. To increase the ideal efficiency to 35%, what must be the temperature of the heat source?    $^{\circ}\,C$

  A heat engine exhausts u;jn 77ux11k;q 9pgh)d ghsnxits 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 output of heat from oul1v a,62iytzt*v mqro*:p6w- v( zecne being the approximate heat input of the secondo(q1y-, 6ump lvt6rcat z*vzw*v 2: ei. 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 coil i n yan)d 0er z:l,0nbqws(dq q90rl1j(s -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 arxq4u3 vf; 7;bai w(f obgie(2 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5.0. Ifn u-z+:m3uud uqdf*(7mj 4vgnsww n/n- 3qj-b the temperatureumdnuj*qn dm wq7s+u3 n/ bnu:3v-4j( - zgw-f in 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 keepo l 5),/lejqv eur4 ms.qju-b+ a house warm at 22$^{\circ}\,C$. How much work is required of the pump to deliver 2800 J of heat into the house if the outdoor temperature is
(a) 0$^{\circ}\,C$,    $J$
(b) -15$^{\circ}\,C$ Assume ideal (Carnot) behavior.    $J$

  What volume of water s;9f; 9ruvrc6b0djue f)0jjz 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) engineol3ps zkll6b,z 47rj0 has an efficiency of 35%. If it were possible to run it backward as a heat pump, what would be its coefps37ll,6 4zjl zk bo0rficient of performance?   

  What is the change in entropy of 250 g of stcp3ad 6/mv rbql/dt48eam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water it +nlb +wwhfdv9kq:z-,3 vh *1 vdoci:s heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy of 8 so fs-jdqed7e9;1n b zcc42b$1\,m^3$ 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 8-9 itasa+yr gof $3.0m/s$ 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 the3(+r: isr g8t k8cei4s y2duku ground and coming to rest. What is krr sd: 8uusg+ic (t38 yik24ethe total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conduc, ixx 1fq;y06a7jcz9z k/ kkflts $7.50\,cal/s$ 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 30f5 iy0ox/,- lzvxi6nd $^{\circ}\,C$ 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 alumm8s1q3rl5cafyz9ly lv, z8w( ;ti:t dinum 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 35 f1e+ggal1v zumzf,j z7z8nat 970 K and 650 K produces 550 J of work per cycle for a heat input of 2200 J. n z,+efjfl18ua 1z5vzgg 3z7m
(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 probabilitie10fiu0g; xi:-0stoxd ic i8kws, 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 order of increasing pr 9p 4pq 6d 9k7ht5rgcikm.rsepq*2 k/wobability: (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 pp rkt hp2qkr4 ei57m*9qk6g dcw.s9/two equal-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hn 4rwoj7,r9;xg ufk7nj) 0vpfand and drop them on the floor. Construct a table 9xnpfg7f,r unr4j0j; k o7w)vshowing the number of microstates that correspond to each macrostate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of electricity p m(g mltwzz81 gfr0;z*:ddx8r er square meter of surface area if directly facing the Sun. How large an area is required to supzw x 8d :g8(mf1dzt 0;mrzrg*lply 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 b )foyuv47bj4u y ,v;48b rcnpb)jur. for use during peak demand by pumping water to a high reservoir wh)yb4o nrr4 v jufb7jvyup8bb.) ;4,cuen demand 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\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–fdsdg z) 42q9n27). The water depth is 45 m at the dam, and a steady flow ratqzdn d4 )s2f9ge of $35m^3/s$ is maintained through hydroelectric turbines installed near the base of the dam. How much electrical power can be produced?    $ \times10^{7 }W$

  An inventor claims to have designed and b0. i c:jkru2kiuilt an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 2k.k i:jc ui0rK, 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 delivers1fux yb/ 3x.8*tozy6xg xfv e) 220 J of work per cycy1fe/oy6 xgz x)v*.3btx xu8fle 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 vu yxn)4) f)p 1ba:erbengine) absorbs heat from the freezer compartment at a teb4pav)nxu1:b)e ry f)mperature 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 develop.cy rp+:vde79) /cp hpa 4xxseed that made use of the temperature difference between water at the surface of the ocean and that several hundred meters de se)dch7vrya+xp/ :pp .xc49eep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars are traveling in opposite directions when they collide az 6pp8-ds-txxj( r 4hsnyh9e8 nd are brought to rest. Estimate the change in entropy ofzxhss8p4(- j8 tn 9-edyh6 rpx the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup)bc)us ha*+pzsv3uvp(:7 z p z 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 ideal heat pump that extra +0t xcdrad(*vcts heatxr v d+cadt*0( from 6$^{\circ}\,C$ air outside and deposits heat inside your house at 24$^{\circ}\,C$?   
(b) If this heat pump operates on 1200 W of electrical power, what is the maximum heat it can deliver into your house each hour?    $ \times10^{ 7}J$

  The burning of gasoline in a car r *ia8 :j*van19d 0hi)yj*fq weaduck7eleases 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 bdw0sdqg3qmv;f0 y9 0 a 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 bgtc1 fy,fdj1 i: :jqi.y an ideal gas in going from state A to state C in Fig. 15–28 for each of i1,1f.:cqt fygji: djthe following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts outcd,2 niq;*frwvn fh 3v(u30na 850 MW of electrical power. Cooling towers are usednfu( vcrawndn3,hq2if3 ;v0* to 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 delivmnt0 ob6m1sdrz4q piw *,mz+g9cf7/cers energy at 980 MW using steam turbines. The steam goes into the turbines superheated isg1/m0m,z7m t4rnc*fb9cp qz6w+ doat 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 about 15% efficiency. Assumqthie; d4y iattr 9 v83e+/qdo-c,4y me the engine’s water temperature oqtao8d4y ttyr+3 /i-v9e;4q, dmheicf 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 injm-2o2gws rm7 a tall cylindrical jar of cross-sectional area $0.800m^2$ A frictionless 0.10-kg movable piston is placed vertically into the jar such that the piston’s weight is supported by the gas pressure in the jar. When the gas is heated (at constant pressure) from 25$^{\circ}\,C$ to 55$^{\circ}\,C$, the piston rises 1.0 cm. How much heat was required for this process? Assume atmospheric pressure outside.    $J$

  Metabolizing 1.0 kg of fat results in aboutd5umi mpxyu11 ff6 ;i9 $ 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 insideef*tjed4cj24h qf;tmh+m 8bz7o t1 n* 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.sk6.jrdv;k0-j, g h no” The humid air is pulled in by a fan and guided to a cold coil, where the temperature is less tha. ;h6vsjkokdjr, n-g0n 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 1.0 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