What happens to the internal energy of water vapor in the air that :u8/h o j hm7l/prprl+condenses on the outside of a cold glass of water? Is work done or h7r 8prj:m lp /h+lh/uoeat exchanged? Explain.

Use the conservation of energy to explain why the temperature of a gas increas1wplpto o/.gw 3;f9k pg5rdl 2 d8th7zes when it is quickly compressed — say, by pushing down on a cyli d.2l3;thr8w ofp 1 g9wtzgpp/7k5dolnder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J cl;qt f3 m7ev kx+g8/z6,xq enof work is done by an ideal gas. Is this enough information to tell how much heat has been added to the system? If so egm3tx,/vkex8l+qzc;6q 7nf, how much?

Is it possible for the temperature of a system to remain constx4wcwl 0q0 w8dp uk6801sc vslant even though heat flows into or out of it? If so, give one 006kcx4duvs1qc 0l8slw w wp8or two examples.

Explain why the temperature of a gas increases whro(+ dr5fax3d en it is adiabatically compressedxdd3(or + 5rfa.

Can mechanical energy ever be transformed completely into heat ojwvb l.fxp6q)y i9 ,c(r internal energy? Can the reverse happen? In each case, if your answer is no, explaincyw (v.qlf)pjb96i , x why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven door open ak:l q+pwb :cuony51(? Can you cool the kitchow bc:kl : nau1y+5p(qen on a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of heat engine effihvmf7rmt:u5z 3abzhzmy 9p*k:zt7, * ciency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature ao(ft/wu x zy),reas in (a) an internal combustion engine, and z,/)tof wy(xu(b) a steam engine?

Which will give the greater improvement in the effinh *lo40b3(c1ndfh zpciency of a Carnot engine, a 1 0n4b3d*fnolzhpch(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 amount of thermafh 1tqz+ 9tanp.ek/k ,l (internal) energy. Why, in general, is it not possible to ptz,a f1pqe/. ntk+hk9ut this energy to useful work?

A gas is allowed to expang6h;zgc1 ik, vd (a) adiabatically and (b) isothermally. In each process, does the entropy increase, decrease, or stay i,1gkv6; cgzhthe same? Explain.

A gas can expand to twu;tju -n47raeice its original volume either adiabatically or isothermally. Which process would result in a greater change in entropy? E r7u; 4-tuaenjxplain.

Give three examples, other than those mentioned in this Chapter, of natura:yn; ew lx(mh:rx7/gze/a t3 ylly occurring processes in which order goes to disorder. Discuss the observabilireyl:zxay/3g (ehxt7:m w n; /ty of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 kg of liqui 0,ktv;(*vuqioi1jfsophnz9 ,vg8. u d iron? Why?vi,utoh 1*, ;g. nj8fi90sv koqv pz(u

(a) What happens if p)qmus;c96;yb 3cdau b30+a)y jwnbs you remove the lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples of irreversibicjc))ma n;+3 y9ubb q6s3psd;u bayw0lity?

You are asked to test a machine that the inventor calls an “in-roojsr3ty,at+kn0+ mw c a3oql hh.x i5(.m air conditioner”: a bigl t3+o05(rq xm ,jc3ikhnht ay sw.a.+ 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 processes (other than t59jg.mwnl y +e2ygg j9aur9, ghose already mentioned) that would obey the first law of thermodynamics, but, if +5 gn ejygw.m999a 2rgu,ygljthey actually occurred, would violate the second law.

Suppose a lot of papers are strewn all over the fl 1nv;a;a nt)xzd2x-q voor; then you stack them neatly. Does this violate -qazv vn;xa)2 dtn 1;xthe second law of thermodynamics? Explain.

The first law of thermodynamics is 64lf. .ax gtnn 7nazr5o0; qz6zz*j sssometimes 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 equix zsnzz.4l n 6rzq0.not fj6sa;7g *5avalent to the formal statements.

Entropy is often called “ 2y:k*kg*t0cebt w yn;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 would tc kb0tktgey n;y**2w :ell you that time was “running backward.”

Living organisms, as they grow, convert pq6z/r-)v0 .dl6cmk.me hiem relatively simple food molecules into a complex structure. Is this a violation of th epq ir.cvl6 e6zm/- .)0mdmhke second law of thermodynamics?

  An ideal gas expands isothermally, perforv*i 05rom-aema lv 9d5 7. gc3fntd9rnming $ 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 frin 2e n)cjx(ae5ctionless piston and maintained at atmospherc)n jn(e2e5x aic 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 79wg lm fh v9*m+z,5x2gdjzkx at constant pressure until its volume is halved, and then it is allowed to expand isothermally back to its original volume. D97m x+k5m*xgf 9 hdl,jzg zv2wraw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal (lq ,p45okubxgas at 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 ilo,qb5u k(4 xps increased at constant volume until the original pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is jb-m*mh)hyylg(ldva 3 m0 /m5/m /zx, kwva,qallowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, and lastly is brought back to its original pressure by heating at constant volume. Draw the process on a PV diagram, including nu,(xdaqygm h)myvm/zkw al / *5 hb 30vj/mml,-mbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while being )kh/gjhhxw:wxy75m (3 2ez i ukept in a container with rigid walls. Ixwe /z)37:( gkx5jiwmyhhh2 u n 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 compressed adiy(zt 1*fcv4y.(v2 fbbaa/sg jabatically to half its volume. In doing so, 1850 J of work is done on the gas.y /(2jac(gbvfsaf. yztv4 b1*
(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 b3hg+tb i rf4);t6zhqof 3.0 atm from 400 mL to 660 mL. Heat then flows out h bh;3ttir qb6)+zf4gof the 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 monatomiyc3u gbvut9s ,1 +xtq6c gas expand adiabatically, performing 7500 J of work in the process. What is the change in temt,s gy 6xbvqtc1u u+93perature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to flow l gx+x)0 c u p6;vy1(l5i/ bi1vybhmwbout 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 gx1myv0 6y;b1(vh+wlli x bcb /)5upivolume 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 Figwv 5z6iwgjxt, qn4 5y/. 15–23 shows two possible states of a system containing 1.35 moles of a mvx5zw 4jw,nt/ y5qg6i onatomic 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 cgddgjvh/6p ))a :5luxw0ljd , along the curved path in Fig. 15–24, the work done by the gas is5)ju,6 dx 0/ lld pahg)gdvwj: $W\,=\,-35\,J$ 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 f7.3gfma1.voufb, b d- a5bnwa gas from state a to state c along the curved path shown in Fig. 15–24, 80 J of hebvmdug ab o5b7 1,fna.f -.f3wat 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 of wo 7vnl ,k)(rxro;k wl cz lhxo0gmf4:,0rking 11n: xmox )f ,lgkr0(hc,w7 rz4 ol;kl0v.0 h she took a noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average meta w.f fyv9,9ykjbolic rate of a person who sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tennis y, f.ykf vwj991.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per day, using t ai15h jlxo11g*r9okfhe time for light activity. How much weight (or mass) can this person expect to lose in 1 year, assuming no change in food intake? Assume that 1 1 15* ofixk1rloga9jh 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 work. Wh zy*ww9ypy ttqjh1z)uu 9wx5, ,)+pipat ish pwu)w9ytx,j1 yz5q9it p* zwy+u)p, the efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal of heat fr otz. l5-rnmd6om a high-temperature reservoir. What is the efficiency of this.5m zntor6dl - engine?    %

  What is the maximum efficiency of a heat engine whose operating temxgqm fm(13lpgk u /xhr.o6jk8nc 39h( peratures are 58g.3(1(3fg/rc6xhmk xp8 9klhno qjmu0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine is mx l9 bi2xu9p a:8qog9230$^{\circ}\,C$. 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 maximum theoretical ury m134dt/ pk(Carnot) efficiency between temperatures r41/3pdutky mof 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 environmew:f-9 s gsyz/qk k2;clnt be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled w:qy -z9wks;g l/2scf kater. 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” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW while using 680 kcal of hewb re mkn-bg6il0;:/ lat per second. If the tl:mklw0 / b6 -brien;gemperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating tempi un j,x ,zt 6;3xbxls5,axlr6eratures 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 pow+qokj,x:d /+bu.el7w uk5jr mer. Estimate the heat discharged per sb/u5jl e:ukq,o.7+ +k mr jxdwecond, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat sctk36;z ;en ,4h40,wpo wmytwwa1q m xource 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 hepsmz+9.jn qe2x eqdvv 4fv4 ;+n+n gc8at 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 outp,ya)h bmoky9 kwr8+i,ut of heat from one being the approximate heat input of tmbykyoawk 8, 9ih ),+rhe second. The operating temperatures of the first are 670$^{\circ}\,C$ and 440$^{\circ}\,C$, and of the second 430$^{\circ}\,C$ and 290$^{\circ}\,C$. If the heat of combustion of coal is $ 2.8\times10^{7 }\,J/kg$ at what rate must coal be burned if the plant is to put out 1100 MW of power? Assume the efficiency of the engines is 60% of the ideal (Carnot) efficiency.    $kg/s$

  The low temperature of a freezer cooling coil is -15 e/ngz 9;pii:bofe6xn/1z3ez,ny : ng$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates with3rutp k6b08suw:em z- 7 0f7t bdkfzp, a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficientj;q;w6 n :/ymb6g t;vj8v pzmx of performance of 5.0. If the temperature in the kitchen outs x;wgv; mv/6jb8p nyj: ;tqz6mide the refrigerator is 29$^{\circ}\,C$, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?    $^{\circ}\,C$

  A heat pump is used to keep a house warmy:4 w lmji.g1 *ny*vrh 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 a k0-ro 1oi k-ju.a-le8dcwc-i t 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 efficide+mr) de+ *caency of 35%. If it were possible to run it backward as a heat pump, what woulm +dde*+cr) aed be its coefficient of performance?   

  What is the change in entropy osb g +p:u7*- yjh3 a;cv,,dczi: mupjof 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 heat1v1g 4lru4li) 4sie lved from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entr.t ( *mm:jn j45ozdauwopy 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 initialwy 8*y5lpp (-vasx2*4 ehlt4qehcjc) speed of $3.0m/s$ slides along a rough table and comes to rest. Estimate the total change in entropy of the universe. Assume all objects are at room temperature (293 K).   $J/K$

A falling rock has kinetic energy KE just before striking the g1j-t2tk c0crground and coming to rest. What is t 1-c2rj0ckgtthe total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod cond-a4)f9 oigxc uucts $7.50\,cal/s$ 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 3tdk8bw5o*1whj zh /j3 0$^{\circ}\,C$ is mixed with 1.0 kg of water at 60$^{\circ}\,C$ in a well-insulated container. Estimate the net change in entropy of the system.    $J/K$

  A 3.8-kg piece of alc zhi.- x42z oceb7z*krjjqbk7vqb //q0 -wy4uminum 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 r23av tmp+ c+ioeservoirs at 970 K and 650 K produces 550 J of work poctmai2v3p+ +er 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 obtaini9:mlflp; om6kng
(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 ordere5bq uak srq(6du w)36 of increasing probability: (a) four aces and a king; (b) six of hearts, eight of diamonds,uqas6bw e)56krq(3 du queen of clubs, three of hearts, jack of spades; (c) two jacks, two queens, and an ace; and (d) any hand having no two equal-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repepk0f43uj)bpd o7p v o3atedly 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 the prob7v4k jopf30)3 po dpubability 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 per square mete1v,u tgqn.rl- uo+3iqr of surface area if directly facing the Sun. How large an area is required to supply the needs of aqt1u.o + gniulv3 ,r-q 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 dema0tv+o g s8aewh gkd 4:1yygl,+nd by pumping water to a high reservoir when demand is low and then releasing it to drive turbineygs+0tyk e g81 +doa:lgwvh 4,s 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 b dhf2 qjw;uc4aqll.-9y a dam (Fig. 15–27). The water depth is 45 m at the dam, and a steady flow rat ;q cfula-2h4jw9q l.de 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 propf*. n3kuiwlib5c, , e4jl/ pbduces 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 bpik*,ip,lujfcl w3/b .5e4 n215 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 effny a(ww9d1 y7eiciency of 0.25 and delivers 220 J of work per cycle per cylyedy a9w w(1n7inder. 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 eng-*o*oaev wpl.pbk) /cine) absorbs heat from the freezer comp.ppv)*l*ew c ok b/a-oartment 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 tnmp4nw6n(7y5 ; hvobmi-l .evhat a heat engine could be developed that made use of the temperature difference between water at the surface of the ocean and that several hund4wb y(. vmh756 -monn;neivpl red 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 oppositnr*ia9 1z5wn ke directions when they collide and are brought to rest. Estimate the change in entk19r5 nai znw*ropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum c9 *xei //)ndutuoxx/m up 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 pum e wyayl6+q7r1p that extracts he76+laryqwy e 1at 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 gasoli kk8s(6m :h5kmmq1+x;d egd hlne in a car 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 a lower opd/ u buec bb5e,fj):lfh)yfbp*57ba2erating temperature $T_L\,=\,20^{\circ}\,C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal gas in going from qbc;)fsr+xf . state A to state C in Fig. 15–28 for each of the following processes: (a) s)+rxf.;c fqb ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Coos.s/d8lce 2dot9uh 4)d0 ,qqj ocoz+tling towers are used to takest8uteoqzo49hc ,sd+ 0o2. q)l/dd cj away the exhaust heat.
(a) If the air temperature is allowed to rise 7.0 $C^{\circ}\,$, estimate what volume of air $(LM^3)$ is heated per day. Will the local climate be heated significantly? $\approx$   $km^3/day$(Round to the nearest integer)
(b) If the heated air were to form a layer 200 m thick, estimate how large an area it would cover for 24 h of operation. Assume the air has density $1.2kg/m^3$ and that its specific heat is about $1.0KJ/kg\cdot\,C$ at constant pressure.    $km^2$

  Suppose a power plant delivers energy at 980 MW using steam turv7s o ; 2l9 p0mfn8:vszpssp/fll.dk3 bines. 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 27pvkn:l9sz3fp fsp. ;os/ l lm0sv8dan 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 a8yw.4r r 1iegft about 15% efficiency. Assume the engine’s water temperature gfi .1 48rreywof 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-sectionalcowy(/ p2yygzzy1a q9m.f ;b7 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 aboutn o2vjml /na/4 $ 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 thjy06 3sgmeto 9e temperature 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 “refrig/1gc+hoc6 aw gerator with an open door.” The humid air is pulled in by a fan and guided to h1c + /6wocagga 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 1.0 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