What happens to the internal energy of h p r1j1/m-smuwater vapor in the air that condenses on the outside of a cold glmp/1 um1rjsh-ass of water? Is work done or heat exchanged? Explain.

Use the conservation of )9n gi/moz)i2k(p)e k8hv ugm 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 decreases when t9m/n z gih8)2v (ume)k i)kogphe gas expands.

In an isothermal process, 37n byj8vn6z*su:z7*a0 6 oeh7j pw a4uy00 J of work is done by an ideal gas. Is this enough information to tell how much heat has been added to the system? If so, how u80 n:jyn6eobuj4v7hya*sw7za p 6z*much?

Is it possible for the temperature of a systi0unu 2zur e..em to remain constant even though heat flows int2iu nu ..uz0reo or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiabatically comprem8 f,jpd. uaxgj )q*l6ssedp 8gxj)m fq ,.jd*aul6.

Can mechanical energy ever be transformed completely into heat or inttg*knwn 4x5 (pp5izg9 ernal energy? Can the reversn*9itz5kg wn5(p g4p xe 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 winter by leaving the oven door open? Can u;u0vq f q5ow4you cool the kitchen on a ho f05owv;uuq 4qt summer day by leaving the refrigerator door open? Explain.

Would a definition of hvdsh8f5 fb*1neat engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in6 k7e e1dy9ccur1h(uk (a) an internal combustion engine,ue6 1r 1d9kcuke 7c(yh and (b) a steam engine?

Which will give the greater improvement in thcf2-w b/s pv.j5bf,olqtip ;: e efficiency of a Carnot engine, a 10 tpf/:wv cfbq,ip;5slb2 jo. -$C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendsjyog1 c17+ gwous amount of thermal (internal) energy. Why, in general, is it not possible tojco1 + g7yws1g put this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) isothermally. In each procea gwxl8ga 6f(axmw- ai(a)y 59ss, does the entropy increase, i6 a )y5g9mg(- xwaawaf8x la(decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiaba nx7 6.x:2.j pp91sxyvz tpn3 gt+djiztically or isothermally. Which process would result in a greater change in entropsd:g6+z3xy7 .x pvnpt2j ixz9pnj1t .y? Explain.

Give three examples, otherfk5 moyk-ej(hkp3 /7 v than those mentioned in this Chapter, of naturally occurring processes 3( -e/f5pkkv oy7mk jhin which order goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 o(e cpydb48 g-kg of liquid iron? Wh (eyo dgc-84bpy?

(a) What happens if you remove the lid of a bottle containi 9 pmgu8j ,e89tqlm5muxmq /-ong chlorine gas? (b) Does the reverse process ever happeum m58 mtoqu qe jg8m9pl9,x/-n? 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-roxi hzf0:s5r x-om air conditioner”: a big box, standing in the middle of the5fi s:x-rz x0h 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 (othe88spvg y;d 57oy8grpp o fb.8sr than those already mentioned) that would obey the first law of theyg8r8ppps;b8og .5dovs7 fy 8rmodynamics, but, if they actually occurred, would violate the second law.

Suppose a lot of papers are strewn allf 4xdg 25gnk1d over the floor; then you stack them neatly. Does this violate the second law of thermodynamics? Exgk4d52fdx n g1plain.

The first law of thermhv0 m8g(wki4 )zqrk h7wtwc*hf66w)y odynamics is sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break evenq46h8crh6 w0w)(7 kkzh)wwtfyvm* ig.” Explain how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it tells us in which directinvr51cdf*tlk ,tym+.nr:j s.on natural processes occur. If a movie were run backward, name some processes that you might see that wo *1vt:dn+r.jc .nrymfl5stk, uld tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simple e9wm k:qu*n3azv,my6/z f s:efood molecules into a complex structure. Is this a violation of the second lafz6,usvm y w akq3z*emn:/9:ew of thermodynamics?

  An ideal gas expands isothermally, rbp8:c l ( p8xmpddl71performing $ 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 fricti4 aj(-dohj2ch dx 75ijonless piston and maintai 4j5dc7j2odx(hja-h i ned 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 iz/qyb;0*7ij*edj g ; kady5zv ts volume is halved, and then ita;50/z 7 qibkjged*yvz y dj*; is allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the follo,nwre-3 xxe(p02 dmxj gr;:bj;+ efy hwing process: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressurrm drwnx +2;fp;e ,3j x0bhg-:( exyeje 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 (absolute) pr jvd-a*p6 4q a;(xgovaessure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at4oq; a* g-xv(6apvdja 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 isn p +qh;:ydk,.npm.dt cut in half slowly, while being kept in a container with rigid walls. In the process, 265 kJ of heat left the ga,;pd qnp hy:.. ntdk+ms.
(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 its volu3 gk,n . ipsbk4,fz)i ,7nwpxvme. In doing sopig .v,,sw3b,ik p7k4fxnz n), 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 3.0 aaruck5 h w:zv7w1:)yvmt(ku/ tm from 400 mL to 660 mL. Heat then flo)w5wh mkt u1vyzarc7uk/:(:v ws out of 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 monatomi2ir3jec9b;drla0rcz8w/ue 0 c gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the gas during earl c/rb c2i 93ju dr8e00z;wthis expansion?   $ K$

  Consider the following two-step process. gw:,x.wg.locnp/9 an 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 the9lp..: o/gaxwcn ,wng temperature reaches its original value. See Fig. 15–22. Calculate
(a) the total work done by the gas in the process,    $J$
(b) the change in internal energy of the gas in the process,    $J$
(c) the total heat flow into or out of the gas.    $J$  ----待选择----intoout  the gas

  The PV diagram in Fig. u1s.ol 2szfl bdf0p td*cj0n si124c715–23 shows two possible states of a system containing 1.35 moles of a m01jfu1stcz7ldss0 n 2o*pcd 2. i4bf lonatomic 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 6w;on-b ahuoxn.k; nx q1,to4the curved path in Fig. 15–24, the work done by x 4bnwt ;h ux6a1; onko-q,.onthe 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 froz-lj+me fd:b/g47axo+b r+k dp if p/:m state a to state c along the curved path shown in Fig.b:+ :+z+odkxp/db g-r i74f fpmja/le 15–24, 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 j5v,s xd3b*ssz+im 85 szissfu , b8e+Example 15–8 transform if instead of working 11.0 h she took a noontime bre i5ssj8s 5+ +b,zf diz8,bvs3uessx *mak and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h; u/w( jb 4rix2 f.v)wemjeb0qzvs7j 7, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs e;.( 2xzbwiw uqvr)vjf 7m4e/70b jjs0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less bo1p8nw79wdr 62s ;cxz cb vm6per day, using the time for light activity. How much weight (or mass) can this person expecbzpm w1;rs 7w 66 n9cbvcox2d8t 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 7c jy.9m/;7 utgrumt.+erepto2y9 cc J of useful work. What is the efficie/7umu ;r9ye .ttgem jc.t p2r+7y c9concy of this engine?    %

  A heat engine does 9200 J of work per cycle wl cxzy7(-k r)ymd0x9+vwqo) zzy; if /hile absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the eik 9 yro mxz/)y(flyqzv-zx7d0)c+w ; fficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operatind-tpoeq/m)1.l3/hun g0 2al9 icj v cng temperatures are 589cjd)n023mhl -pq uv1to .enc gl i//a0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperatu.x 0d8k5vf/hh9 ik xture 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 operates at 75% of its maep8qxw +or):+ u 2xmueximum theoretical (Carnot) efficiency be:u+p wrm +x8 o)2exequtween 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 hott cxph0* / gy;csogxq-)er than ambient temperature. Liquid nitrogen (77g;y0 h -cs/*xpqog)cx 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” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at them1h+:v:/jg +p:ev mpkm0z xna rate of 440 kW while using 680 kcal of heat per second. If the temperature of the heat source i 0:k mz:xemnpv1j:+ + gmp/vahs 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating te*g;wdhgal f w; vf 4og5sv);j+mperatures 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 plan, d *vw1 pvf75vdwbdc3t puts out 550 MW of electric power. Estimate the heat discharged per second, p*db1ddf,7wwvv3 5 cv assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat /xaqov; k 1t.ivn2vf 7source 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 ird01c dl67cvdts 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/aslugc k1g6pqd* (i 0/pdi3d, steam engines work in pairs, the output of heat from one being the approximate heat input of the second. The operating temperatures of the firstdp(0 q6icas/1g kdidpug 3l/* 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 fc;6bs yo .k.em hh6u0q8 iu 9l.mtkba;reezer cooling coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates with a in a *f ag3n4bdx,(eiu2m8 v gng7 xwh:is6 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5.0. If th-d ug,1 +urfzn3p)ium e temperature in the kitchen outside th g-duz),frun1+im3pu e 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 7. wvahp7m8se-xj if)to keep 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 at1a1v a fxd h )vhkyyj6t5ok-41 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) eng1e02;bc ks2v gnee n-vine has an efficiency of 35%. If it were possible to run it back2 2ken bene01sv g-vc;ward as a heat pump, what would be its coefficient of performance?   

  What is the change in entrbhrtfz4(vnp08y)- j : sb1k 7i1edtg aopy of 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 heated fdl7k l,3nl( jf6 hqfr.rom 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy ofcyp, /idjg *o/ $1\,m^3$ 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 init;qfc:4m3ek rzial 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 - w;b 8/w k3/t)5l3 wgtlt/sdocwcqxl energy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment as a result of this col8;k/w5w lbo / tl/xctc)w dsltw- 3q3glision?

  An aluminum rod conducts hda/,;o gf4ke $7.50\,cal/s$ 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 30 a- pbay;9+mwukmwuw( +5.r jb$^{\circ}\,C$ 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 alumx arvne,( mi1/inum 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 betweh+:zao/d:m-g fbgm4 t en heat reservoirs at 970 K and 650 K produces 550 J of work :fm a:g+4 gh-dtm/ozb per cycle for a heat input of 2200 J.
(a) Compare the efficiency of this real engine to that of an ideal (Carnot) engine.    % of ideal(Round to the nearest integer)
(b) Calculate the total entropy change of the universe per cycle of the real engine.    $J/K$
(c) Calculate the total entropy change of the universe per cycle of a Carnot engine operating between the same two temperatures.   

  Calculate the probabilities, when you throw two dice, of qei x,shh 1uqz(cve8k1e/6 l,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: (ai/u c:cni s39zqj4ej2) 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 (dz:jiucinj/e q3c s294 ) 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 f)*7zi owz ob 3mbb tmt+o,p97qloor. Construct a table showing the number of microstates that timb+97 b b*3 m7,)zoqztopwo 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(f1 jsea .1cvf vp v92w-zj:au) can produce about 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is requirejzfc .vus-v:2f( eaa pjw19v1 d 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 atut p0 *b/(ja3:qqt-t) ni q6vn uzcp+ high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumped to 6 qqi: at/ptz+0qu-bcn n(*3vtt )pjua 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. 15–27). The water d -bmsphpnib* ss2l/, 1epth is 45 m at the dam, and a steady flow rate of bbln1smis*p-2s p/,h$35m^3/s$ 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 design.mn.3m 9cn1; wecpwlfed and built an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rew np.efn9 ;cwmml1c3.jecting 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 0.25w nz s99/fv5 ekw s5 jhppzzq73(x.0ic/cke x5 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 c/p nz(sqvw.xzhe w3x5i550es ck z9k/cp7f9 jycles 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 hek-rs8w b.3 kiqf5)nhjat from the freezer compartment at s 8 ).jq ifkh3b5kwnr-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 heat :pfi*j ptxua 5;h6 8umengine could be developed that made use of the temperature difference between water at the surface of the ocean and that sevh:a x;*ft6up 5upmj8i eral hundred meters deep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars are traveling in opposite dib*guv 3s k 7(4m4*/lfn)fu y)aqmdpbfrections when they collide and are brought to rest. Estimate the change in entropy mpf)(3* *qkbud/7nfs4gm f)vbu lya4 of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup at 15;5ywymi n:21bf-s kmvixs- p 4$^{\circ}\,C$ 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 of6dixx x; (7p5d5benf(q5dqka performance of an ideal heat pump that extracts heafqepb55((dd; x6kq 7ndxia5xt 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 gasol e 5dr (m(fwk94eb(rzcine 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 operat3p ef .)8h(zslsmupu2ing 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 statwefez:yib hf4/40 )gee A to state C in Fig. 15–eef4h4 efz i)g wy:/0b28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient powerd *:*e ch1kj1 mgat2;verk d0v plant puts out 850 MW of electrical power. Cooling towers are used to take awa1 hkrgev dc2j0 tdem v:a1**;ky 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 st0+*nhyvf ri;1 b:jocxeam turbines. The steam goes into the turbines superheated at crhfn vbx:*i j;oy0 +1625 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 a0h1bk c4 nc(ejt about 15% efficiency. Assume the engine’s water b (hj41ec0ncktemperature 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 in a tall cyli.f1 x5mcbwr z:ndrical 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 romid*zu .v +.qdp,nfg b*.tf-esults in about $ 3.7\times10^{7 }J$ of internal energy in the body.
(a) In one day, how much fat does the body burn to maintain the body temperature of a person staying in bed and metabolizing at an average rate of 95 W? $\approx$ =    $kg/d$(retain two decimal places)
(b) How long would it take to burn 1.0-kg of fat this way assuming there is no food intake?    d

  An ideal air conditioowilz9 / /qj1kon-q4wner keeps the 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 “refrigerator with an open door.” The ;gaf46c9pzfs2 f qud; humid air is pulled in by a fan and guided to a cold coil, where the temperatqp f ;d9ffz;42g6c suaure 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