What happens to the in v,e(- xo8c4ai 9p1mlue hri2rd .xa0nternal energy of water vapor in the air that condenses on the outside of a cold glass of water? Is oa nvi, 1mru9hcd(i-xex4 p 0.a28erlwork done or heat exchanged? Explain.

Use the conservation of energ 6(hj fpup.cwv.+ 5bkry to explain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature d.6w. fprhjb(c+uv5 kp ecreases when the gas expands.

In an isothermal proum;,4zsz2 z,t: q8*bylbnl yhcess, 3700 J of work is done by an ideal gas. Is this enough information to tell how much heat has been added to ty s 2y blz:;zu4,n8qbl ,*thmzhe system? If so, how much?

Is it possible for the temperature of a system to remai, h1 -pspj )h-*7wkob;cpo)qbdlg th:n constant even though heat flows into or out of it? If so, give one or two exbblh ;ok*p1o)h7 d)- s:hgpct,j-wq pamples.

Explain why the temperature of a gas increases when it is adiabatically com8 ny 4q,0sziwyj6-3eego2 xvw pressy s0 -2ve8wegyj3ziq o6wnx4, ed.

Can mechanical energy ever be transformed complai it5 8: *rcdbwpce*4etely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, expla4t: icd5*c8i *a prbewin why not; if yes, give one or two examples.

Can you warm a kitchen in wint1du ns0z-dgw5s 9hcma/ 6)pge er by leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrp9geads6/1huwz 5nc)m d0 sg-igerator door open? Explain.

Would a definition of heat engine ef:2/zdn jhvpp 4ficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-tempera ets0tt uld)r.r 8,p,qture and low-temperature areas in (a) an internal combt,ep,l )0rrustt.q d8ustion engine, and (b) a steam engine?

Which will give the greater improvement in the efficiency ogrf/c 0- r2oe),dgysv f a Carnot engine, a 10 dfgs)-r ryoev0/g c,2$C^{\circ}\,$ 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 thermabtmh*, 8i hsu)lad3,r ;t*m h :hb(gcdl (internal) energy. Why, in general, is it not possible to put this energy to useful workc,it buh hl)mr d,tdmh :38* *sb;g(ha?

A gas is allowed to expand (a) adiabatically and kz-a ;h7cow+8y ju ye((b) isothermally. In each process, does the yw(uj z ck7oy;+8ea h-entropy increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volum y)kse(sl9(qli o 0i+jl8bj3v. l;yaye either adiabatically or isothermally. Whi+l sll evyail kybs83(.90i(;) jyoqjch process would result in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, o6n;w ( n ymk:r.zj8f0fca ph4jf naturally occurring processes in which order goes to disorder. Discuss6:rj0fn;h(n. y4pczaf j 8wmk the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid i1,,jw .li0rq jv7jehy ron or 1 kg of liquid ir,je7q0wry ,lhv i1.jjon? Why?

(a) What happens if you remove the lid of a bottle containing chlorine zcbof2 /:r3bk.l i: ebxfyp)kp 4wd*; gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples ofby2lprfd4pe bzic3k;k *ow) f.: /x:b irreversibility?

You are asked to test a machine thateajli6 m s121tn3tbcj3l,jl))z 4hyv the inventor calls an “in-room air conditioner”: a big box, standing in the middle of t4e1hnt,)lyc l zl6bivt 313sm2) ajjj he 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 those already mentioned) that would obey u8u7peex9rn91w2;;(l5po kf ic qd db the first law of thermodynamics, but, if they actually occe8pq( n9u;lcwbo7ukepi2;5 x1rd9 fd urred, would violate the second law.

Suppose a lot of papers are strewn all over the b u0s8.dzw7vo.jqh-jfloor; then you stack them neatly. Does this violate the second law of thermodynam7b whsv0jd.o zq.u8 j-ics? Explain.

The first law of thermodynamics is sometimes whimsically stated as, “You can’t2rvf o ;/ixeh) get something for nothing,” and the second law as, “You can’t even break even.” Explain how these statements could be equivo2 i;fvrh/)xealent to the formal statements.

Entropy is often called “time’sik- -7id7pk)rpyc:6mc9et wfe vki5 0 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 tell you that time was “running backward. vw-cte )ycp-r5im7f:07d 6iikk 9ekp”

Living organisms, as they grow, convert relatives 0oxl+apzj;9qe. 4di i50svbly simple food molecules into a cx5ie0 j. aplq9dis4v+oz b0; somplex structure. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performing;gk517k-ukl ;n0zg cevbs 6(ww 0iqtd $ 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 frihjq.h/2wejh ,ctionless piston and maintained at atmospheric pressure. W2jw,h/ehhq. j hen 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 tev*fl06ljtg +gty *7 volume is halved, and then it is allowed to expand isothermally backg70 6yttlv+tjl ge** f to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal ge -jeu6n/1 xtvas 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 is increased at constant volume until tj -6evux ne1/the original pressure is reached.

A 1.0-L volume of air initially at 4. 7lhpd 2n7z73awqkmg25 atm of (absolute) pressure is allowed to expand isot3m 2npgaw 777 lhdqzk2hermally 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 is +wws 6,mkooy9fdp c/,m2c b5xcut in half slowly, while being kept in a container with rigid +mxwoc, c yspk59,f2 dobw 6/mwalls. 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 compressed adiabatically to xd 8nr+h ;jw b7.2ugo, slpq9yhalf its volume. In doing so, 1850 J of work is doho l9jyb7gu d ,2;r+.xw pq8nsne 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 to sf n4o+u.dxov gg,w6+nz2-sg56zw n ef)d-dz tal pressure of 3.0 atm from 400 mL to 660 mL. He+gog,z 5-2gz4nsevd 6.ufdonn w xs)wz6d+ f-at 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. 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 monatomic gas expand adiabatically, perfooaig9bn- s ,p7jv3qe1rming 7500 J of work in the process. What is the change in temperature of the gag1es9qb7- p nia3 voj,s during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to flow out of n: d1/e;o*(9j*fmlurjwk yk q 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 itwmoj(1dkn /; eufj k *:q9rl*ys 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. 15–23 /nary(cf1sopmt:j aw 67o9e ( shows two possible states of a system containing 1.35 moles of a monatome7m fw/jy:a 9(po(oran1t6s cic 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 acq0g7iv,dn8j xvu- )along the curved path in Fig. 15–24, the work done by t,7-)n0gdqux8ca jivv he 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 curecu.s. 0rgwm3d l0rd* ved path shown in Fig. 15–24, 80 J of heat leaves the sdur.esmlwd 0r0g3 c.*ystem 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 0bhk.yf0moc94 ues3g of working 11.0 h she took a noontime br3.o4f sbgmuh09 y0ek ceak and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person wh1x1h49 r bpheoo sleeps 8.0 h, sits at a desk 8.0 h, engahre4 11 hoxpb9ges in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per day, using n4/mr(e x f1ajs3:6mw rrctj1 the 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 kg of fat stores about 40,000 kJ of energem /rac34wf j sm1nx6r1tj(: ry.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while performing 3200 J of useful work.+(fyw /t2tkrz6f/q+h(lqvs o What is the efficiency o(owzfqy vk/(+q tr sh2l/ft6+ f this engine?    %

  A heat engine does 9200 J of work per cycle while absorrz9e2*smi 3ytp i5 1fch 8pur.bing 22.0 kcal of heat from a high-tef3rsu9zpc h.1t iyer*mp i5 28mperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a )s;z; vib elcm-x2sy7,pg )xdheat engine whose operating temperatures are 580);ild mev yxbz ,g);sc-7x 2ps$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a hxa +3x3csf/sb i x;gn9eat 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 r.32n33s )jrxzj1 i4gfl cmcaat 75% of its maximum theoretical (Carnot) efficiency between temperatures of 6n.jca3)3zlrf4c r mjigs 132x25$^{\circ}\,C$ and 350$^{\circ}\,C$. If the plant produces electric energy at the rate of 1.3 GW, how much exhaust heat is discharged per hour?    $ \times10^{13 }J/h$

  It is not necessary that a heat engine’s hot environment be hotter than amy gh/k0+7xt qabient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What w/qt+gha xk 07yould 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 usie8r2u -sih+kghd *sd9 ng 680 kcal of heat per second. If the temperature of the heat source is u*eh8 +gsri-9dks 2d h570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating tempera7s l6-dokyw ri (ki. 8i/vit9atures 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 oi9xe 3;ygk1va mtr/06sx ) 3hklz9 fxxut 550 MW of electric power. Estimate the heat discharged per second, assuming that the plant hasa3z3xk 9xf1 st9mikrh;l 0y)6xe / xgv an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source aj . qcsno0q ab;68pjf9t 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 exhaustsbkf5;sinci;2z,uq4c8lo6hvi h jh1 4 its 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, st3puu wo2n9h 1qeam engines work in pairs, the output of heat from one being the approximate heat input of the second. The opeo2qp unu1 9w3hrating 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 coolin+t ib3y 4*zxg5xrqr0 jg 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 82 kedz0dvg(u qm7in+a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefs/-ypivq*+b vq) lz: yficient of performance of 5.0. If the temperature in the kitchen outside the refrigerator is 29v sibq+/:qp)lv*z-y y$^{\circ}\,C$, 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 at un5l4gogtls(w6u-e 9 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 watervr-sj -r7-b8mxtmjo 4 at 0$^{\circ}\,C$ can a freezer make into ice cubes in 1.0 hour, if the coefficient of performance of the cooling unit is 7.0 and the power input is 1.0 kilowatt?    $L$

  An ideal (Carnot) enginx,ifk/s nm kvhz -,3elu (o81ae has an efficiency of 35%. If it were possible to run it backward as a heat pump, what would bkl- sh(,mz/n3ef , kax1i 8ovue its coefficient of performance?   

  What is the change in entropy fl0vn(-s5fzp gny.xb824xhk 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 frowyxr- f19ia. )oag;bh1c fkg7m 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entrop)-psl;hidlg q+p *me/y 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 init8pt+ ,ay x7wsrial 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 ground and c .r w4odee1u/tl 6cgfdd xyzw3/5 *z0xoming to rest. What is the total change in entropy of the rock plus environment as a resu5e.erlz /zwo6t*1f d/0g4 xd wucx y3dlt of this collision?

  An aluminum rod condvcszr.4 kg,.d*a6am t g pcr5f ya1/;lucts $7.50\,cal/s$ 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 3o9( 5 ; 9fodydycnr(dt0$^{\circ}\,C$ 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 alu dxx/ *:by4q*bfztfa .h8 gu3ominum 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 plx3: e sq;l3jheat reservoirs at 970 K and 650 K produces 550 J of work per cycle for a h ql:3xe;p jl3seat 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 probabi(ov1 grnmsa;e 9 nugd6l+xx-0lities, when you throw two dice, of obtaining
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hh by+rc4*gfr0 ands in order of increasing probability: (a) four aces and a king; (b) six of hearts, eight bhyr 4cf g*r+0of diamonds, 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 iz-(kqyy* m 1uf4z(tb*g5c z i dnz9h,xn your hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probability of obtaining z(hbfqcm i4x k*yznuz 5zy-g 9,d( *t1
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce ab r09auysdt y1a1g m)+aout 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is requig9r y+a1a tmd)a0uys 1red 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 tb8mye8rye*. peak demand by pumping water to a high reservoir when demand is low and then releasing i*8myy. e8rte bt to drive turbines when needed. Suppose water is pumped to a lake 135 m above the turbines at a rate of $ 1.00\times10^{ 5}kg/s$ for 10.0 h at night.
(a) How much energy (kWh) is needed to do this each night?    $\times10^{9 }W\cdot\,h$
(b) If all this energy is released during a 14-h day, at 75% efficiency, what is the average power output?    kW

  Water is stored in an artificial lake creahe nen61c635*i qvdk lted by a dam (Fig. 15–27). The water depth is 45 m at the da enq1 63hel6vcn id*k5m, 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 eng utomas ew 5u(8;s*v 7ar7v:ynine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy atat u7v5m;*:yauws ( snrv8o7e 425 K, and rejecting 1.50 MW of thermal energy at 215 K. Is there anything fishy about his claim? Explain.  ----待选择----yesno 

  When $ 5.30\times10^{ 4}J$ of heat is added to a gas enclosed in a cylinder fitted with a light frictionless piston maintained at atmospheric pressure, the volume is observed to increase from $1.9m^3$ to $4.1m^3$ Calculate
(a) the work done by the gas,    $ \times10^{5 }J$
(b) the change in internal energy of the gas.    $ \times10^{5 }J$
(c) Graph this process on a PV diagram.

  A 4-cylinder gasoline engine has an efficiency of 0.25 axyp8ah/*1v ej5v izz)nd delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles per se)*v5xph8iy1jeva z/ zcond,
(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 Carno0p )es+v5pmg et engine) absorbs heat from the freezer compartment at a temperature of ) ms g+ep0e5vp-17$^{\circ}\,C$ and exhausts it into the room at 25$^{\circ}\,C$.
(a) How much work must be done by the refrigerator to change 0.50 kg of water at 25$^{\circ}\,C$ into ice at -17$^{\circ}\,C$    $ \times10^{4 }J$
(b) If the compressor output is 210 W, what minimum time is needed to accomplish this?    s

  It has been suggested that a heat engine could be developed that made eewu*li j;vmu00uq*: use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures may be um eqj:*we0i v*uu 0;l27$^{\circ}\,C$ 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 a338izsx u:t ropposite directions when they collide and are brought tri: 8ts3ax 3zuo rest. Estimate the change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup at 1ov2gppq -f(9t z -+y sy8c0yah5$^{\circ}\,C$ 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 ey09r*5.h 0zxpts.kqd:c pq upump that extracts heat froqdqtzx.*y5.9p 0hsk0ecrp:um 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 rele)jr ey-ektxc qcz wj4k8253d ;ases 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 opemzvo*9q )s1:kg qjfv)rating 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 ir: oqhaqp 9o :*pix7qfx+6dn5n going from state A to state C in Fig. 15–28 for each of the follo+fqd5axir xqhpn6: o *9q7:o pwing processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient powervv lvq- x2 1nkakgp028ry- (re plant puts out 850 MW of electrical power. Cooling towers are used to take alkr -v-v(8ny1e0ag vkxrpq22 way 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 e8in0m7r- 9ii)j asxvsnergy at 980 MW using steam turbines. 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 an ideal Carnot i 8jv9ssim)a7xr0in- 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 aboutvu9 q*ugo+x-7o th5a p 15% efficiency. Assume the engine’s water te +u7aph u- *vox95gotqmperature 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 cylindrical jar of cross-sectional gyg-c hz1z;t -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+h73(llpz ;aysal r,hid k//r 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 conditioner keeps the temperature inside a room labuui8k0i3ekb/ yl 4 st6:+mnwq)8dat 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 essentialltyami-nyhvn20b) ske 0y *tq9s8d 0v;y a “refrigerator with an open door.” The humid air is pulled in by a fan and guided to a cold co *h mntnb08;ytv-9ke)qi02y d svys0ail, 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