What happens to the internal energy of water vapor in the air that c-phr* zsy)-z-q;, adxqd)h u dondenses on the outside of a cold glass of water? Is work done or heat exchanged? E*-dr,p)shzhd u z aq-y; d)x-qxplain.

Use the conservation ovv21*io. iqvqf energy to explain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature io2*vq v.1qivdecreases when the gas expands.

In an isothermal process,:l i)kl9wd9 wi 3700 J of work is done by an ideal gas. Is this enough information to tell how much heat hasw)l:9k ldw ii9 been added to the system? If so, how much?

Is it possible for the tempe ;p6 jq8 cdg1;:r.mu0xbzimb zrature of a system to remain constant even though heat flows im; 68ibg1b0 r; cduqjzp.:xz mnto or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases wh)t53za;wxsg/ r zca,6ll lpq2en it is adiabatically compressed.lxrll q, w3a gs/;2 z6atc5pz)

Can mechanical energy ever be transformed completely int.lq 9u-eonso.iq yimu y ;.-/no heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain whyyqi- uey.i9.;-mn l squ/.ono not; if yes, give one or two examples.

Can you warm a kitchen in winter by lslk 1sug*iny4ngaw g ui+5+3*)9 ezfweaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigeratorguiwn zk+ew) y*1*saf gl5+4g3n9usi door open? Explain.

Would a definition of heat engwuuq7 5ag;eyt h;ua05 ziza/;ine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-teo *l)f pi54e 5mnjt-domperature areas in (a) an internal combustion enoo- 5tne4dim f)p*j5 lgine, and (b) a steam engine?

Which will give the greater improvement in thep kgf8 qik)wiq: .8 i:3bo.idu efficiency of a Carnot engine, a 10 . dq3 ibwpgiq8oii8ku)kf:.: $C^{\circ}\,$ 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 thermalor2-5p vwmx+6es ae ,t (internal) energy. Why, in general, is i +s amtx, 5v2eer6-owpt not possible to put this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) isothermally. In each p1 2na.jvj6jg17gfx jrrocess, does the entropy increase, decrease, or stay thegj6 nr11 g.f72vxj jaj same? Explain.

A gas can expand to twice its original volume either adiabatically or isothermal0:pz4xye suh8 zi,nt7j,/s vhly. Which process would rz8x 7s,yzv ps/he:hjn ,i4ut0esult in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of na2i029 hk7cngvygq jgv pdhody +n-5qd)0 x/9bturally occurring processes in which ordjn o5/0dgx0y+qyhkvp d9d 72b- g9qg)n c2i vher goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entr f izx21: ivp-,cqr*uuopy, 1 kg of solid iron or 1 kg of liquid iron? Why,* v-1fuiu 2zip:qcxr?

(a) What happens if you remove the lid /gty0 s05ut nknhaw -+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 irrever5a/t y- 0+nwsg0hnu ktsibility?

You are asked to test a machine that the inventor calls an “in-ra yd 73p1b9:-o1*hprskrh xaroom air conditioner”: a big box, standing in the midd-1hrpkxhy:rs9b 137ro p aa*dle 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 (ot-1kd it2zqz 4-essl9rher than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would zsd q4z-2kl ei91s-trviolate the second law.

Suppose a lot of papers are strewn all over the fz ,/d mmu/k,(hg01i azsdw .mgloor; then you stack them neatly. Does this violate the second law of thermodynamics? Explain/uawg kdz0,g hi(1mds.mm, z/.

The first law of thermodynamics is sometimes whimsically stated as, “You hsjf4 +)4xgvu/ sawdgz40u6 w can’t get something for nothing,”uas4v0 wx s)64udjz/gw4 f gh+ 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 tellshk*tj58un f ) o)zijmnd if9-; us in which direction naturo fni )-ih;fjd5uz k*98)mnjtal processes occur. If a movie were run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convj3o2 3v,cj ojyert relatively simple food molecules into a complex structure. Is this a violation of ,o2oc33vyj j jthe second law of thermodynamics?

  An ideal gas expands isothermally, perfcgfgqd .hhpm- f5b,58 yg )lp8orming $ 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 frictionvg fi(p .,6zgcless piston and maintained at atmospheric pressure. When 1400 kcal of (vgig c6pz.f,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 is halsihl*fodir3 95pc nz n*go*5*ved, and then it is allowed*zn*ril ofp gon*h9*5c di35 s to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas at atmo;gs se ekvtxx jxa4 - ulu:z8hf9.0r91spheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the originlx08-;jsag 4ke u . 9zuxxh1rsft9ve:al pressure is reached.

A 1.0-L volume of aiwfm s, .2ecizqfdn/q1a1 .v 1ir initially at 4.5 atm of (absolute) pressure is allowed to expand 1q .q11c , aidmfs2/nifevzw.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 numbers and labels for the axes.

  The pressure in an ideal gas po 6anv/cukqn7k7* -u2m ge(g is cut in half slowly, while being kept in a container with rigid walls. In the proco7q*n2 kuep(- 7vucm/kg ag6ness, 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 ups(+ 1 moy;-,nrui7c qvb6dibit )5phalf its volume.pv (imni ,;7 cb+u rbyi-tu1 qs)65opd In doing 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 constant total pressure of 3.0hsj.x.d+ awytoja *1 w. la(f2 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 reaches its original value. Cah(awj j.l2. .wy+xo1 tfs*daa lculate
(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 anw er np4)sxw(84,l chz9p(bxq ideal monatomic gas expand adiabatically, performing 7500 J of work in the process. What is the changec xpzhn(p xw,swr9q le (44b8) in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to flow out of ane/pe *iwol,s59yw,zk 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 sz9elyw5o/ we k p,,i*Fig. 15–22. Calculate
(a) the total work done by the gas in the process,    $J$
(b) the change in internal energy of the gas in the process,    $J$
(c) the total heat flow into or out of the gas.    $J$  ----待选择----intoout  the gas

  The PV diagram in Fig. 15–23 shows two possible states ovvgafi06h2; fo4a 6p*s;mm sh f a system containing 1.35 moles of a vm2gssv i;4opf*a 6;6f0hh mamonatomic 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. 15–24i g b//7mmbt7y, the work done by the ga7ib//g t my7bms 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 stat cjh uj4z1sk.1e c along the curved path shown in Fig. 15–2h jkjc 4sz1.u14, 80 J of heat leaves the system and 55 J of work is done on the system.
(a) Determine the change in internal energy, $U_a-U_c$.    $J$
(b) When the gas is taken along the path cda, the work done by the gas is How much heat Q is added to the gas in the process cda?    $J$
(c) If $ P_a\,=\,2.5P_d$ how much work is done by the gas in the process abc?    $J$
(d) What is Q for path abc?    $J$
(e) If $U_a-U_b\,=\,10\,J$ 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 transfo6fwr: +i bwlmrhj(::zrm if instead of working 11.0 h she took a noontime break and ran for+z6 (b:i fwwj:r mhr:l 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sits at a 9gr9o;nz/bux,g,j .muvgtrou8b c 9 7desk 8.0 h, engages in l9 ,gb98; / g c j7xruub.go9mvotznru,ight 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, us o htzjm7y/x((ing the time for light activity. How much weight (or mass) can this person yohx((mj/z7t 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 -7 :bnl-j 7ignx2fruqxgk 39 owhile performing 3200 J of useful work. What is the efficiency of this engine?ong7 -7 i9: kfnblqx2 r-xugj3    %

  A heat engine does 9200 J of work per cycle whilxj 7 o+ke:p-cyxks d f/z;:be:e absorbing 22.0 kcal of heat from a high-temperaturk e- jx:x;ck:ozsy7 f+e bd:/pe reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engizn9jm*pl5(95kq oc fwne whose operating temperatures are j9l *(9opm5 cnqfz5kw 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperat0y 2c.q1tfjqaure of a heat 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 op5-/hus/c(rtgmh i m w+eov)v5erates at 75% of its maximum theoretical (Carnot) efficiency between hg c5tmoir( 5m+vesv -h/)/uw 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 hot h w9e-yr5kd e6fvzv4*ter 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 5wv*9-k6 ry4 edfzhveK) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rakc *,; rd+k(ml tcy2;go5gt5ik:z jsg te of 440 kW while using 680 kcal of heat per secondg s+k;2d 5kgto:glkr c(ctjy z5im; *,. If the temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatures ac(sufbgiyw qj.,.(9q re 210$^{\circ}\,C$ and 45$^{\circ}\,C$. The engine’s power output is 950 W. Calculate the rate of heat output.    $W$

  A certain power plant puts out 550 MW of electric power. E;/k gusi :zj(ystimate the heat dischargedkz (ius jy;:g/ per second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizeszadx) hv3z tpm5jag/9n (r +:j a heat 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 its heat at 2m;xno2f *c xc350$^{\circ}\,C$ 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 h;n- 8rfblk.v:1s0vh v8mr wu heat from one being the approximate heat input of the second. The opelkmr:v8sh;. ur1 0hw nvfv8 -brating 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 cuk ,ycg7rr6g/ooling coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-fr8d,1tqhrtl 7ueezer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigeratoevi:zu8ti,d/q2d 5hl r has a coefficient of performance of 5.0. If the temperature in the kitchen outside the5lu qh,/ tz2i8vddie: 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 warm)hjc m34p 9qkx0,:voyoxgu h6ad-o6c 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 0sn9*0 gw opjf4$^{\circ}\,C$ 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 s9v(vpfeg( ;f 4fcv;sit were possible to run it backward as a heat pump, what would be its coefficient s;vc ( gf9p4(;fsfvve of performance?   

  What is the change in entropy of 250 g of steam at 1qnv .n -(ml7pt00$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of watetq ,1 5ufos/s fe+9ddvkn8gv6r is heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy ofle)g 8qm/as6f $1\,m^3$ 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 ino zo: :/x6ibflitial 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 jo0sh rg+2ap54m,fo fqr.9 q njust before striking the ground and coming to rest. What r0q5. fq4o,s+9hpjog2m fnrais the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conduc-uibz h hewyx s3 3b+j*s1j7-gts $7.50\,cal/s$ 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 3e+.y sddaxs5f88.tx b0$^{\circ}\,C$ is mixed with 1.0 kg of water at 60$^{\circ}\,C$ in a well-insulated container. Estimate the net change in entropy of the system.    $J/K$

  A 3.8-kg piece of aluminum 5p xrrn6si6 qy iyqout,1:rwf/z320z 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 5zzu-j(yrvofdutq)v: )k4 9 mK and 650 K produces 550 J of wou()d mv uvtr5- zq9)yj:o4fzkrk 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 probabilipdeuy.ekaf6 ,o*s65kiu:h 2p ties, 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 fiv 3fg11mov0assju dj ce/z:,:b e-card hands in order of increasing probability: (a) four aces and a king; (b) six of hearts, eight of diamonds/:sfjzabcos0, 1jm g3v e:1du, 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 repeatedly shake six coins in your hand and drop the b3 a1:kt3b y.aqnat4f3j*lgf m on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the jn3 g att4l3 y1fakafq*b.3b:probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce cg cp.7dbk(d91e m)r/6wkfn dabout 40 W of electricity per square meter of surface area ifp(6k wd.dckbfg)7e1 mc d /9rn directly facing the Sun. How large an area is required 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 uxzj01 0ht .hpya6:g qqse 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 at a rqq hjzy h0.txa61pg0: ate 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 d s5ap,o+co6e cigx/+eam (Fig. 15–27). The water depth is 45 m at the dam, and a cxe6 ioc,5 p g/+so+easteady 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 o: jaaxg nk5+yy, ple .maka2p;k.*x)that produces 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 215 K. Is there anything fishy about his claim? E k2 ;gkaj.aam,xak yy: 5lpep n*+ox).xplain.  ----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 c12dp es oq/6man efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. Whe q6o/s2 1dpmcen 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) abs:j mnt*oo(tsca: yp3;.o g a9qorbs heat from the freezer compartment at a temperatureo3qt(om;y a:ctp*og :.j9a sn 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 b()qt/rfe .d- l.ub.6 ovbjtgheat engine could be developed that made use of the temperature difference between water at td.l(ue r6j.qvog ./b-)b bft the surface 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 opposp4 f(7hbtqa0 r/zcq(l ite directions when they collide and are brought to rest. Estimate the change in entropy of the universe as a result of this collision. Assc7 trza (p4hfl0/b( qqume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminu*0fllwsti 1uub,6 j6-uv2ya dm 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 rc zz*g hs4z( b*ld4l9an ideal heat pump that extracts hez4 rd*h4 zcg*slz(9 lbat 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 re xdfg13 rjgu08so ox+9:t)slx leases 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 rwv,lqe 3 d:ql 8;+qgsoperating 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 id2no1 n k8rbj 8+sunar4v/c3ifshts20eal gas in going from state A to state C in Fig. 15–28 for r 8+ 8bu njnnsik0 1o2s2cv/s3ha 4trfeach of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Coolingkpu b)-w gfwjjjt- 2r i4:yf45 towers are used to take away the exhaust heabjugrwjf)p5i:f 2tkw- -4y4 jt.
(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 86:f5nnc;s ccdjavz*wys6 z: turbines. The steam js;6zydn nfc c8 w6sa:5*vcz:goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbine operates as an 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. 0gng/ + /v w5c wgb6fx9brdh1bAssume the engine’s water temperature of 1cv0gg 6wn b/fwd9b/+ rbgh5x85$^{\circ}\,C$ 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 tpoprt3 ;6x gowti( i89all 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 abou(-zcspu, )twp 89d ylzt $ 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 temperatuahws f-j7ex6vp d cej:a+81n2re 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.” The humi79i.ngp-, mwsbjh8m g d 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. Estim ,im7sn 8pg 9gb.jhw-mate 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