What happens to the internal energy of wrox* g 2(rs6ug 6ikd (sej.kv7ater vapor in the air that condenses on the outside of a cold glass of water? Is work done or heat exek d67ri2 (su6 gkj.(g *xosvrchanged? Explain.

Use the conservation of energy to explain why the temperature of a gas incr 43*x;k(y l zc6pqleejeases lx*eqj;3zk(p 6e4yc lwhen it is quickly compressed — 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 ideal gas. Is this encmws.w7uv p)o9x5 t5 t :ax(cxough information to tell how much heat has been added to the system? If so, pac c 5xu5xm9) vww:os(tx.t 7how much?

Is it possible for the temperrxdhw;s,d( yj9s(** g;ntr in ature of a system to remain constant even though heat flows into or out of it? If so, give one or tw**wgi(n9sx;jrhs,yd; d r t(no examples.

Explain why the temperature o/wl.m ijeabam93z )a7 (kbfq 1f a gas increases when it is adiabatically compressb 9 aj/(ama lf3.mzb7 q1kew)ied.

Can mechanical energy ever bsspvu:rf+vls )vt q5qe0;l 70 e transformed completely into heat or internal energy? Can the relves ls00v)pq75r f+ vsq;tu:verse happen? In each case, if your answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in w- p3*+qwwutixrjg,r: vs2k9b w,t 8 vhinter by leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator doow pwx:3+rj sgt28*qw9vhib- ru ,t,vkr open? Explain.

Would a definition of heat engine .u4t 2ajcbac 2m*(lrfefficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and lowoa3q;g*hoyjo/ ojpa ( 7y* mdk7ee +f0-temperature areas in (a) an internal combustion enginag0/op hej;qekjaf3m*yoo 7d7 o+y*( e, and (b) a steam engine?

Which will give the greater improvement in the efficiency of a o)fo14.cn o(hyxg.u pCarnot engine, a 1hfo.y.n ugopcx)o4 1(0 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous am6 -lk/morowqcj9y* v /ount of thermal (internal) energy. Why, in general, y/*mk lj6ocrqwo/-v9 is it not possible to put this energy to useful work?

A gas is allowed to expand (a) adia +5mc ysqh 12s, b8mljajx(gu6batically and (b) isothermally. In each process, does the entropy increase, decrease, or hb q mms(,1+sy8gc2xj 5aujl6 stay the same? Explain.

A gas can expand to twice its original volume either adiabatically 2l(y.suwx35 ,vo0-rwo ud wfzor isothermally. Which process would result in a greater chanu52.w-y,v (0wz 3dfs or lowxuge in entropy? Explain.

Give three examples, other than those mc /mt,z juys,l6x8qp7notw ,:v:tie+ entioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the observability of the reverse process.pes+cx,j tmw6t v,q z,8iu7: t:/ylo n

Which do you think has the greater entropy, 1 kg of solid iron or 1 kg of liqu fec/ -/-auqb(qy: kvt/ozx.tid iron? Why/xqt zb-ce.y:fu/q/o( a-vk t?

(a) What happens if you remove the lid of a bottle containing chlorine gas? (b)gc t*g/c,s-z r Does the reverse process ever happeg czt- s*,/crgn? 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 an “in bilnb:f 5e9q duw4r*q9p)h 7m-room air 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 a l7u)b ed 9q9 qp:4fhwnim* r5bstream of cold air coming out of it. How do you know that this machine cannot cool the room?

Think up several proces loip)b4 5wd1csjt .v+ses (other than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violate t5j4 lvo ipbtc1).s +dwhe second law.

Suppose a lot of papers are strewn allm spmciz +z92u.g06lju 16 yb24m tegm over the floor; then you stack them neatly. Does this violate the s+46l2. 20emm1zp b9mj guzscy ugtim6 econd law of thermodynamics? Explain.

The first law of thermodynamigg: 7u0z) mnos.ueln90 8jbixcs is sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how these statements could be equi9)jnu:ego gblixnz. s m807 0uvalent to the formal statements.

Entropy is often cal uh+:ac-d4 :,qoenj sbled “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 se,d:bshoau nq:+4 jc- ee that would tell you that time was “running backward.”

Living organisms, as tpjf-* 1r;. f55jmqr1 pghltjjhey grow, convert relatively simple food molecules into a complexhflf ;j1mp*rqj g. 5tj-jpr15 structure. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performi8 *6zjn:f1 jtgbvprw .ng $ 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 w9 e6rqn m8( dzvwc4+mcylinder fitted with a light frictionless piston and maint4meq dn r68vc9 (wm+zwained at atmospheric 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 volume (gaa +puakq :,is halved, and then u(a:+ga pkq ,ait is allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following pro* x/n+ l.mb .r kdsr+ 0bvg xqkplmf/-8p83bkqcess: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pr8bmdkk .0s- 3 8plrvrxx *gl+f/m/k n.bb+qqpessure 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 ij ipdrj8l.*ra2 p:vo 3nitially at 4.5 atm of (absolute) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is vi.:r ja3dpl *2prj 8othen 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 ideg n.il9ay1t2eal gas is cut in half slowly, while being kept in a container with rigid walls. 1a.nyi2egl9 t 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 gas is comprfl9 e yr*qvx nms5dr1:p :(zhow(x :s,essed adiabatically to half its volume. In doing so, 1850 J of work is done on:xsrvl :m onh 9xf5,p:dzwys*eq ((r1 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 fr0zq5 fjk0oh w)om 400 mL to 660 mL. Heat then flows out of kw5jq0z )ho f0the gas at constant volume, and the 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 monatoubed-tps-bk v(n *87amic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of tdba s 7tu-eb8-k*v(n phe gas during this expansion?   $ K$

  Consider the following two-ste r3(dxm5 s6 ot:6xwlzsp process. Heat 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 temperature reaches its original value. See Fig.6zs6m (x o:wd53rxslt 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 statesh aj-w55l18h 8dpl jmp of a system containing 1.3wd8l-h 1lm8aj5ph 5jp5 moles 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 from a e9057 vk1g *qq rlzsry) 5moixto c along the curved path in Fig. 15–24, the work done yv x1kg)o97eq im *5l5rs0q rzby the 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 s2ok o6 77pc.au hlnh8mm0jqb4hown in Fig. 15–24, 80q2 lou m hmbp.h07jkcn6487ao 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 instead+5+bjy j eru6u of working 11.0 h sheu+6r+juey5 bj took a noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who s copzf)vv76f4vo i6a2leeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tenvo64zop2 7v 6f)fcivanis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lo)k; c.8uia7/erfz - zj;iznby se weight by sleeping one hour less per day, using the time for light activity. How much weight (or mass) canku)c j 7i/-y bz8z;feinr.;za 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 of heat while performing 3200 J of useful worw8,laszz78 ;t1s xsi vk. What is ;wv7s ztzs,ia1x l 8s8the efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal of heatv ju w3ki ,1celj5n-ei.ba.) c from a high-temperature reservoir. What is the efficiency of t vical1. -k,ciej 3.)e5 wbjnuhis engine?    %

  What is the maximum efficiency of*76.8xc7gmzh rnr (ibu6yay d a heat engine whose operating temperatures are 587ci(gb n hadrur76z6m y8xy* .0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a h15hffce3d*c d1; we ueeat 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 m 1zlg8 , pf, 8cgrs)ybv,7qccjaximum theoretical (Carnot) efficiency b c,fs88,cbq,jy l 17)vgzpcrgetween 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 e 8a) nmew*ntr0nvironment 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 liquid nitrogen “fuel” )*tnr a we0nm8(Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW while using 680ew(y*+ 1ispmf kcal of heat per second. If the tempersmp i*(1w +fyeature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operati4 v)ld3da.w dvng temperatures 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 electc .yk53 51-x6 r7qk ;pfhhx480ehewhf cpj qedric power. Estimate the heat discharg5h h480e.rw;y edq5 x3e-7phf6pkkc jhq c1xfed per second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat sour9v44 unucx b3: y+pzaxt*pyw *ce 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 its heo rj:;+-fbbbqat 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 rva 2w92o+gsb onx7b- from one being the approximate heat input of the second. The operating temperatures of the first a-bo+x9vw2 rs7 ob2 gnare 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 coi 2z1 nl*. o 27t8 h:mbpbx8cboz*aukrsl is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operate-yk3t8z .-jmrly r c,ts 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 4afn2wi h7 *ng5.0. If the temperature in the kitchen ha7nwi n2g4f *outside the refrigerator is 29$^{\circ}\,C$, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?    $^{\circ}\,C$

  A heat pump is used to keep a n8v4n ymcwl(6 nbcw1*mu.dr4s tf i;;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 at bshi4m oz*ba66l+vd ;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) engyruf 11mivb3 se:y7ai s7kht/c o-2e4 ine has an efficiency of 35%. If it were possible to run it backward as /crv7 3iifh2b 14u oy1 e-y:ksame7sta heat pump, what would be its coefficient of performance?   

  What is the change in entropy ofh4cy:tem5f 5 e wpah71 250 g of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is he;2g wlsmr7gy- wg3va8ated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entrop(*x,eoch* yvda , -svghl0f 0-mlpc ;bx+i f7wy 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 spyu (wb2n(xu) a+bo( krmy i07peed 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 energyu 3hqy9 )d0n:se/dyp(bpq;f,t aa -wm KE just before striking the ground and coming to rest. What is the total change in entro,:-f0;/aynpewd )9sd(3thpuq by mq apy of the rock plus environment as a result of this collision?

  An aluminum rod condug/hs r.zxd8+a cts $7.50\,cal/s$ 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 3 5mm0j,c8 c,za1 lmi;b/d runv0$^{\circ}\,C$ 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 alum/m5 cyl4v tl3dinum 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 ybqkqyk,5w eid;/* ) v970 K and 650 K produces 550 J of work peq, wyke; i )k5by/v*qdr 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 throwga45- zfp-bd-79;n kkzmyj ie 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 probability: (a) w0g7e+dk xemk6f g7,lfour 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 acmf+d,ek0gle 77k xg6 we; 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 the f78qdnjn0 y rm8 o)zgwo 10b7giv0 rtu1loor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probability of8or )bd0 g1untn8go0rjv70iw m17 yq z obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 44x9)mspc wb9fjur/ y80 W of electricity per square meter of surface area if directly facing the Sun. How large an area is req8) /rc9 y4 9wxsfubmjpuired to supply 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 for use during peak demand by pumping water to a high ressm z q,:3hfbw1 e+vux1ervo+hvw1ze1 3fqs,bx um :ir 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 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 lakefvos/oq;0.rjh */3ly zt myg. created by a dam (Fig. 15–27). The water depth is 45 m at the 0qo.tzfjlyv ./ m;g*rsy3 /ohdam, 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?    $ \times10^{7 }W$

  An inventor claims to have designed and built an engine that prujq ,m(kep z1n-hn/g( oduces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.50 MW of thermal energy at 2qu-n(me,gj/kz(hn p1 15 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 an0c j)pipzcj 9 jl +xnn91q:pz( efficiency of 0.25 and delivers 220 J of work per cycle per cpjp cz 01qi)n9njl+c :9 zpxj(ylinder. 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 engine) absorbs heat from thei3ak*r y( ij50 wgo,;l :clviu freezer compartment35v,kiljiu oy;ag0crw:l *i( 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 that a heabxw ;5nj 2. rr-k*im+ly+a -eizlkxi +t engine could be developed that made use of the temperature difference between water at the surface of the ocean and that sew2xk.z-+i - bik;5y+errml jiln a+*xveral 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 tr5y,wuck*1khg n+ zde(6*nz wsaveling in opposite directions when they collide and are brought to rest. Estimate the change in entropy of the universe as a result of this collghcuz,16n dnk zs(we**+ykw5 ision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated alumiwl4mb:1 ci:u nzw-:bm num 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 coefficient of performance of an ideal heat pump that extracts arkb.o (vw+ ,v6tzg4rheat fromvk+oa. g6,t rv(rzbw 4 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,ad s3lbt- t8 ati-5useleases 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 a lower hr.2up**g pukg17hj)e15kvs,adkml operating temperature $T_L\,=\,20^{\circ}\,C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal oor)y ub)g- o,7 yhz6a1ahj /gm9b:ifgas in going from state A to state C in Fig. 15–28 for ygf 7ou,m:oozg jha9-/b) 6 rh)y1biaeach of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Cyl.+-m n -ck mh()poxpooling towers are used to take away they+(hc lm--n ox)p m.kp 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 stek:g/rn xwv5s e r+ac)0f 1- ,yuixgp(zam turbines. The steam goes into the turbines superhr(5ue 1cza /x y :pvnr,0)-fwigg+kxseated 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 about 15% efficiency. Assume the engine’s water; 8v(qc( w2ttyb hf8zqhiz *y3 temperayc * vz( w8 qf(tbyqz2;83ihthture 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,u/ ejkjt+2u mu fn2z) in 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 abo3qm4 ytsrm6x2 9a:ck +mhp6d ch (idw:ut $ 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 room at 2c:st.n gk41eo 1$^{\circ}\,C$ 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 “refrigeratord :3 v1kb:hccy with an open door.” The humid air is pulled in by a fan and guided to a cold coil, where the temperature is less than the dew point, and some of the air’s water condenses. After this water is extracted, the air is warmed back to its original tempehb yd 1:cvck:3rature 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