What happens to the internal energy of :m-t5t (jd fjud:vbjvg2o56 e water vapor in the air that condenses on the out-og2 6j 5em(bt:u t:vdfjdj5vside of a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain why the temperature of a gqgos)b*i,deaa/y/ ab/ h2-lu as increases when it is quickly compressed — say, by pushing down on a cy*/)dy aoub ba/2/-s a, ilhqgelinder — whereas the temperature decreases when the gas expands.

In an isothermal procesolcc. n)f 3gw6s, 3700 J of work is done by an ideal gas. Is this enough )w6ocnl fg3c. information to tell how much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system tav y(;4b 3wjolo remain constant even though heat flows into or out of ; 4jbyalwv(3o it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiabatica 95* xdnqagtki162, v,uk;b/vplqo. ewcj rl(lly compressk,a5;6wvbqriln d*.xuoe k/ tv2jc9qp ( gl,1ed.

Can mechanical energy ever be transforme; zwym2t1 a+igd completely into heat or internal energy? Ca2 ;+m gytaiwz1n the reverse 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 yoe 0(a1*fdw mngu cool the kitchen on a hot summer day by leaving the re1n*mwd0f a( egfrigerator door open? Explain.

Would a definition of heat) u+n 8 i9m7sv9orkavr engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in q *4rk(kosvm/w lmu.8 vat8*mglavf5 4 )7ayg (a) an internal combustion enginevtulv8/wr5q m kf *)4gl*4avmk. 8y s7oa(amg , and (b) a steam engine?

Which will give the greater improvement in the eff n :v 2m-ktdr+ m)2+e+cqjwfzhiciency of a Carnot engine, a 10 +ztr h):wjdmq2e2 ++ fmkv nc-$C^{\circ}\,$ 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 thermal (inte s ox)ogm/)smhhbnnoo)8*.g8rnal) energy. Why, in general, is it not possible to put8*.o shx n))omnhgo/)sm b8 og this energy to useful work?

A gas is allowed to expand (a) adiabaticalwp.:c /jl2o bvly and (b) isothermally. In each process, does the entropy increase, decrease, or stay the same? Expj .ob:pcl2w/ vlain.

A gas can expand to twice its original volume either adiabatical(wg9iszru. rwoa,5 p 9ly or isothermally. Which process would result in a gre5 woiz 9ra,uswrg9 p(.ater change in entropy? Explain.

Give three examples, otherjg88xatnk: n: than those mentioned in this Chapter, of naturally occurring processes in which : ka8nj gt8x:norder 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 kg ofwef. j)rc5q.3qkq- go7r :f fjkp50q f liquid iron? Whfj:5fg3 0cj q-qk kw.rf )q5e.orfp7 qy?

(a) What happens if you remdcm9zfm nu*oycw,-i:r 4di4 7 ove the lid of a bottle containing chlorine gas? (b) Does the rever-rc,d4dzof 4nmwmc7 * 9 iyi:use process ever happen? 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-room air condisk vb,;(*il:7 hkdiu bx4umi+tioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air comhk7u(u+,:d;4bs km * iiv ixlbing out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than t a7d* p(wc/wv zij9a j3hcib8;hose already mentioned) that would obey the first law of thermodynamics, but, h*pj/8cwzc bwa9 jd i;7a3i( vif they actually occurred, would violate the second law.

Suppose a lot of papers are st3he0ebn6h2lxc( lo -trewn all over the floor; then you stack them neatly. Does this violate the second law of thermodynamics? Explain.bc- txeo(6hnhe 0 2ll3

The first law of thermodynamics is somv crnpiwm.g+ 16zr o (kah540o88bzweetimes 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 equivalent to then8rw k. v 6z4pe zaw0 rm15(8hc+igobo formal statements.

Entropy is often called “time’s m lpf87a-f .aqz8cny,m hvi,6arrow” because it tells us in which direction natural processes occur. If a movie were run backward, name some processes t8.c mhiy 8vpnzl ,faf, a6mq-7hat you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively sd+i zzl1n+lg1+tmi y 2imple food molecules into a complex structure. Is thli+1ydm+2zlgz 1t +niis a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performig5y -dx 3e s(rrb(5jjgng $ 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 frictionless piston and ma9 ,x,qu).mqbrw;fzy6 wxs tq9intained at atmosph yfb)6xq9,; xwt9qwm,sur qz .eric 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 b6 7k+0,c, h nnm8qc(o ajalvsits volume is halved, and then it is allowed to expand isothera0,h+c qj8c m(6v7 bnk losna,mally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following p.(0mo 5l1v 5rbx xlkl. *2 rcbbqzz(korocess: 2.0 L of ideal gas 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 the original pressure lk bmrx lk5*15bz q(.vbo.(2xlz0crois reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is allowee 4 i,*ouaxzek. ;pz*hd 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 proc4zu, ieha.* xk*po;ze ess on a PV diagram, including numbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while being kept in a s5p a-iw 1mgo+container with rigid walls. In the process, 265 kJ of heat left the gas.1m+wps o-gai 5
(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 compresq- ph3khq+xm m*n./ i anb*g:gsed adiabatically to half its volume. In doingxnhg+ nhm*b k-p /*:qgim3. aq 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 pressurenglzg,ty-6rp )9f n*l of 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the press 9-)*f,zt g y6lngrlnpure 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 adiabaticall3s, a90ldaioty, performing 7500 J of work in the process. What is the cl,a3 i 0tsoad9hange in temperature of the gas during this expansion?   $ K$

  Consider the following two-step procesrz 2ktr6wydtm co7+s rgh(722s. Heat is allowed to flow out of an ideal gas at constant volume so that its pressure drops from 2.2 atm to 1.4 atm. Then the gas expands at constant pressure, from a volume of 6.8 L to 9.3 L, where the tempe7gsrtr6cw(o2m7 t+22yzrd hkrature 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. 15–23u+8q6 thy;b +p)vw zal shows two possible states of a system containing 1.35 moles of a monatomic idvu+q)6p ;z yaw8tbl+h eal 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 ufru.h 1g7tl1 a to c along the curved path in Fig. 15–24, the work done by the gh1l rug 71.tufas 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 s yj4wxb3(3 t rzdi(smb-i/3lq tate a to state c along the curved path shown in Fig. 15–24, 80 J of heat leaves the system and 55 J of w/ sxlrz3jidti (bq-4(33ywmbork 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 yr69 62crn ffo3jg+wdv1 1 mkhExample 15–8 transform if instead of working 11.0 h she took a noontjo+rwy dh n21916cf3krm6 fgvime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of afy0apy:tr z o8ua5) w2 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 1.5 h, and runs 0afa tw r:8uyz)o5p 20y.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour lep8cprp9 q ,ellh 04e/nss per day, using 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 olrp e49 hn8,0p /lpqcef energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhaustqp**,6w9uqad 808+ ck czcvzyxd3 tors 8200 J of heat while performing 3200 J of useful work. What is the effzp, 886 0qvccdcq9*ay*ux 3zorw d t+kiciency of this engine?    %

  A heat engine does 92lt6zo f-jx9/9cg q4 ko00 J of work per cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. What i9-x l6k q9zj/ gcoft4os the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating tempexg7hk 2qmj+w0 ratures are 52 7g0qx mh+jkw80$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a hsl0ytbhq g;iu v*g0. a02oh7 ceat 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 maximum ,.ztlxi uk/,hjejmat):e2 *ntheoretical (Carnot) efficiency betwemik ,,tj).z/xu2nja h t*lee :en 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 env xdc:/2bg) 8grec;s 1xydpb n6ironment be hotter than ambient temperature. L ny8g d/xdc:;bg)6r bpc2sxe1iquid nitrogen (77 K) is about as cheap as bottled water. What would be the efficiency of an engine that made use of heat transferred from air at room temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at(mtpoav,*kzg7r :0j:3 admi npaa n:8 the rate of 440 kW while using 680 kcal of heat per second. If the temperature of the heat sour o::d7mmi ap*apr(k:3n0 n agtvzja8 ,ce is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperature. ke .1mer3pzes 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 power. Estimate hrq tk4de7.rky)uky6 0s5 33usdq fyxd65ss 2the heat discharged per se qud kxs3 tqref4y 06ds) 57hkuds52. y63skyrcond, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes hh):ft:v:p5ylk rfeke op:c27f8g a5 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 exhaus hc)go( n(bmp4ts 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, stc;t9 x4i4ii+9uqfh yfeam engines work in pairs, the output of heat from one being the approximate heat input of the second. The operating temperatures of the y +ixh4; f9ftuc9q4iifirst 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 mkgos+jq1j6yl k g1,d)y: a l:ght *d.is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer opk2-oamd i4:4 tcfy0a ferates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficuufq fnxx2,g,bby -aa1: 4lg:ient of performance of 5.0. If the temperature in the bgf-ban2:qya: ,1lxxguu, f4kitchen outside the refrigerator is 29$^{\circ}\,C$, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?    $^{\circ}\,C$

  A heat pump is used to kvr-8 1ebk0 ipgeep 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 atcvv-3i .fks46l ;h /:sgxzxdp 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 as.0c ltkbzs+3 )d;qf h1qs1nwn efficiency of 35%. If it were possible to run it backward as a heat pump, what s ;f.b11w qkz q h)s0l+3ndtcswould be its coefficient of performance?   

  What is the change in entropy of 250 g of ;a hh,xh5 :+ ;eudey jya y(nwi5b8p*csteam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heateypdvjci+( 2+mvc:.3 ,1zd u xxl vrr:gd from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in ento ;ex1 ocgen.(ropy 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 ini * dh7dt);vnbk6 6)if1 kpkfhcau2n:xtial 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 94m-pm/amzd nKE just before striking the ground and coming to rest. What is the total change in entrzmm /ampn 49d-opy of the rock plus environment as a result of this collision?

  An aluminum rod conducts gc 0-zy oa.;fc$7.50\,cal/s$ 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(o1qg vc8vt7g $^{\circ}\,C$ 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*w g;ajgzfs;kh/h- wc+v6sfm ;9+ (dzs1 pojq 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 re ( xn3j1-ybmbeservoirs at 970 K and 650 K produces 550 J of work menx3b(-1 by jper 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 ; (7pqkd8 oamjyou 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-car1 4xfkl qz8*ipd hands in order of increasing probability: (a) 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 (d) any hand having no two equal-value cards. Discuss your ranking in terms of microst1lq8 p i4*xfkzates and macrostates.

  Suppose that you repeatedly shake six cou )xg-n;(x .x az8er crsnch--ins 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 probabil-zxugc.-rh ) (n8-x exnars;city of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of elect- k xlw 7iz(ylcd3+ou.ricity per square meter of surface area xdcz l(i.k+o w37u l-yif 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 use rcr(5ie+r0od ny7 p;zduring 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 thy;p zi+ dc(5reno0rr7e 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 az5 bd6641 jtdiq5jygkieoef/b7 3q8kn artificial lake created by a dam (Fig. 15–27). The water depth is 45 m at the dam, andi87/ g1kb5fjqq66je eob k yi5tzd34d 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 lw)4oe+3q n-sjkb 3 helpr6 jbho/5 b: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 rejectingb e+/:w 4 phnq3lbhjl6kbso-e3r 5)oj 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 add1y+wg2(wzoa+eksk kpf(- ;fzib * :n efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles per sedfo +bz sw+:(k( 1iykegwk-zap2;f*d cond,
(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 e.tp 9,ht8qjv q. nwbe5ngine) absorbs heat from the freeze,q jn 5ptht be.qv.8w9r compartment at a temperature of -17$^{\circ}\,C$ and exhausts it into the room at 25$^{\circ}\,C$.
(a) How much work must be done by the refrigerator to change 0.50 kg of water at 25$^{\circ}\,C$ into ice at -17$^{\circ}\,C$    $ \times10^{4 }J$
(b) If the compressor output is 210 W, what minimum time is needed to accomplish this?    s

  It has been suggested that a heat engine could be deve 3rapmy-p38 3n.pd gg;e7d sbwloped that made use of the temperature difference between water at the surface om -3p3gepdd ;7w ab3spr.8gnyf 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 opposite directions when t v*9(grk.yr 1i ;vmohb 02+hiu t0zncqhey collide and are brought to rest. Estimate the change in entropy of the universe as a result9uh(t0.rbri vohzcyg+ 2 ;0*mkn v1 qi of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cuple*73ogz/ )3ijj9sox064 xq q0kpvs tuu)y qg 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 ide(egb ,vaag,s;r 6g0teal heat pump that extracts heat from rg a;bsa tv,geg( 6,e06$^{\circ}\,C$ 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 gasolined.h,0pst*z02d jj ggs 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 operating )w g+3omxe oz5 9sqc)otemperature $T_L\,=\,20^{\circ}\,C$ 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 state A s +xya1hdy. do:pls1; to state C in Fig. 15–28 for each of the following processes: ( :xlash ;1o1py+ydd s.a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power *s0 1(zo6ec ip9go6qkn khfu6 plant puts out 850 MW of electrical power. Cooling towers are used to take away the exhaustcug96* oq eo 6hps10k(kni 6zf 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 t8at(vw0gw ad+urbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat in river wate 08+(av gwdtawr 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% ehl0ph+t1et 5 pfficiency. Assume the engine’s water temperature of 85ptt51hh+e pl0$^{\circ}\,C$ 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 areh0e:nk 5asackb h.*l,a $0.800m^2$ 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 fatl12fyp7rr yyr,.ny :(ozhd5j: 1whk x results 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 conditioner keeps the temperature inside a room at 21 ql6 u/cwstug:*xo14-r8qky+t;ds s x$^{\circ}\,C$ 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 opet4yv xl5lik499rz:a ni bl(-l og;h u0n door.” The humid air is pulled in by a fan and guided to a cold coil, where the temperature is less than the dew point, and some of the air’s water condenses. After this water is extracted, the air is warmed back to its original 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 o b;9lv40lloxly k5haiz(t :9-ngru i4f 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