What happens to the internal en4r *m i mjn dn7 d+ha*x1tizcpp4q z17ri6t;:jergy of water vapor in the air that condenses on the outside of a cold glass of water? Is work done or heat exchangen*7d pjj4atz4zmi1hmq*cr6xr ind 1+ t7 i; :pd? Explain.

Use the conservation of energy to explain why the temperature of m kpgczn( -w. -1t)zhaa gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperattnhm (wcz1.-pgk) z-a ure decreases when the gas expands.

In an isothermal process, 3700 J of work is done ;wiwgycw-yp)qkhgh,9 vf0/1xe gl 0 8by an ideal gas. Is this enough information to tell how much heat has been added to the system? If so, how m0) f8hql ,/p9;hkg -eiwcvg w01yygxw uch?

Is it possible for the temperature of a system to remain ct +us-p 4bi-z26r kiwbo, zez+u4h0bponstant even though heat flows into or out of it? If so, give one or e2r,4sbtibo -+bz6p0wu4+z i-pzu kh two examples.

Explain why the temperature of a gas increases when it is adiabati mciki7z.,a*97dt i:u/,qga 0liai dbcally compresset*zi0. ba7m,9 dgi ul ikqdc:,7a/iia d.

Can mechanical energy rc if7q -;wg*eever be transformed completely into heat or internal energy? Can the r;rq c*-fgew i7everse 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 sbhx69y mnm1m6e+hw; leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refriwb+xn9ym61eshm; m h6 gerator door open? Explain.

Would a definition of heat engine efficiencyfy37 *zdu+a5 reo;u j7fyhey9 as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in (a) an intjspth 1g,2lsz4y jh )2ernal combustion engintl1hz2pj y, s)4 2jgshe, and (b) a steam engine?

Which will give the greater improvement in the efficiency of a Car ev8x x:e..w v5vybx70 zcp*fe4:kd*kw (vvegnot engine, a 10d .(*peb*4.7:x8xx g c:k vewev5yv fez0 kvwv $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous amount i on ,-t*wm)zlof thermal (internal) energy. Why, in general, is it not possible to put this energy to useful t,zin olmw)-* work?

A gas is allowed to expand (a) yh 7x m 2,nmdwz9 s8qes.l26wjadiabatically and (b) isothermally. In each process, does the entropy increase, decrease, 6.z8j 22e,mdn mw yswq7x9s lhor stay the same? Explain.

A gas can expand to twice its original volume either adiq0vgqk)m7ya ;1qgp gx-- jp7 labatically or isothermally. Which process would result in a greater chaq mgqqvkpyjg ;- p-01)la7g x7nge in entropy? Explain.

Give three examples, other than those mentione5:1svp, lnemud in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the observabilvlpn ,es5m1:uity of the reverse process.

Which do you think has the greater entropy, 1 kg of solid ir t lt;ha5 wj)z3m2al8fo u ,zd1nf94keon or 1 kg of liquid iron? fj4,9f 3th1 ;lu5ezon z8 2k ta)dwmalWhy?

(a) What happens if you remove s/ hpomjh7 ;j1the lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Canjm/sohj7p; h1 you think of two other examples of irreversibility?

You are asked to test mt.) yo/cczd:is ft61a machine that the inventor calls an “in-room air conditioner”: a big box, standing in ydt)mosct 1:.zc if/6the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air coming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than ysjxfm3,er+ gw23w s kmiw9+, those already mentioned) that would obey the first law of thermodynamics, but, if they actuallfr2 ,,iw+ +s mm3xs3ey9kjwwg y occurred, would violate the second law.

Suppose a lot of papers are strewn all over the floor; then you stack them neqsvd;*t3.t:ql +aa n qatlq na;vtq* l3+sa.dtq: y. Does this violate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stated as, “Yo,:m:vmal,m9(dag tjvl 6ybz 7u can’t getb9:mga: d ,tmvmjz(l7l6 v,y a something for nothing,” 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 calleh jgmegj+. , h-.27( okvpxmnsd “time’s arrow” because it tells us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that wouldpgmoh(j.n ej 7 sxhgv-km2., + tell you that time was “running backward.”

Living organisms, as they grow, c;oiw.o,mo 9 w ulj;ffqj+ xu2k rx.2 1w-wejb:onvert relatively simple food molecules into a complex structure. Is this a violation of the second law of thermodi j.2o k. oww fu,w-j+wj1l eq92of rx;:mxu;bynamics?

  An ideal gas expands isothermally, performin q wl6e3lk((tki s3/eig $ 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 frictionl w+f4fachnpz ,9g 5jy2ess piston and maintain jghcpzf5y2 4nf9w+ ,aed 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 c5ahl2g46 jsf9 zv 00jwqyu8g xonstant pressure until its volume is halved, and then it is alloweg2wh0uygv qfa8j06xzl45 js 9 d to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of thebh2ry+g.nxlwh 2hdk5vr 7 v05 following process: 2.0 L of ideal gas at atmospheric pressure are cooled at constanlkg5x0 2bvv7 dhrnwh5 hr+y2.t 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 is reached.

A 1.0-L volume of airba bxh +tm .wv+c).i0dlpz4;z initially at 4.5 atm of (absolute) pressure is allowed 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)xlvbmz . ;b+ zah c4tp.wi0+d 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 cut in half slowly, tu tnr l5id0b:0t z2.dwhile being kept in a container with rigid walls. l52bn0 zdt: 0dur.tit 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 half 6 p kh l33 1wmux0zak4 3s3.ncltoqh9jits volume. In un36 l3sxcp4qj9.owlk33 hmtak0h 1 z 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 3.0 atm from53+mpvjbh+dpq as 44k 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowpkj3 b4 d+4qvs +mhpa5ed 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, perfo s4ar1,dh mkzg-56akdrming 7500 J of w,64kkh5ar zsd mdg-1a ork in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat3p +w lba ;7y*guid)s)sscd swd7 q;x3 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 temperature reaches its original value. See Fig. 15–22. xs3b ldgu ;;c p)sd7 iqd+ aysws)*73wCalculate
(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 of a system containing 1.r ,h d0v+f 6cn;2kpimr35 moles of a mo vdcrhpi;,nrf0m2 6+k natomic 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 uxk .d*fet w2oro6 pnhh 70*)yfrom a to c along the curved path in Fig. 15–24, the work done by the gas ish h u7yn rof*6.kp0d e2)xtow* $W\,=\,-35\,J$ 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 curved p j 9sq2 i6bl5 u0pmwh)/ahp+qbath shown in Fig. 15–24, 80 J of heat leaves the system a/0m qw h2)pq9pjis5b 6lbhu+a nd 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* g;tll ojt:asl)hrj.cc q/ 5wd;fs 0: instead of working 11.0 h sd./:q;lj clt*;cts )o hjl 5sag0f rw:he took a noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sitsupyxq0(z.5 t g at a desk 8.0 h, ez 0 xug5qt.yp(ngages 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 homb zm++fo0h,sur less 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 of enemz+ hf0sbo+m, rgy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heatg/jmd f1:)t kb while performing 3200 J of useful work. What if:/1dt g)mk bjs the efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal of heat;edeqh ,d3 34lmy5 vpe from a high-temperature 3plq4edh;3d 5v,y em ereservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operatn f1h ca+p1po.ing temperatures are 580 1 ppcf+h1ano.$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine i*sd ql fqct8l6b5c 8(xs 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 theoretical (Carnot) efficf 3+8e3qsa/ lk9 tbdlm45mgomiency between temperatures o m mm fle3lb 45a/ktsog89dq3+f 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 thatskfg*;wku) qu 2 b)f*a a heat engine’s hot environment be hotter 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 K) to the liquid nitroqwu;gf k2 uk fa*)*s)bgen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW while using 680 kcal r++h 3k(mcwgrpc 4 q7aof heat per second. If the temperature of the heat source 34(q7 cwmp+grh cka+ris 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operat npib h85h-2tu tq+k8ding temperatures 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 5z3juha. qyfq73e+y+p c+ zwxout 550 MW of electric power. Estimate the heat discharged per second, assuming that the plant he zcz73jp+xahwyq u+ y3+.5fqas an efficiency of 38%.    $MW$

  A heat engine utilizes o)4y:(fbm pm7epxdn 8a 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 358wk/r 9.mx m frlwn36u0$^{\circ}\,C$ 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 heat from onvjig;s2y20 v v* b6z)j ift4h znab4:qe being the approximate heat input of the second. The operating temperatures of the first are 67 byivb4jzi;j2 q6zh:s2tgf n* 0 a)v4v0$^{\circ}\,C$ 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 -o k+d ixxk3p;is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-frokm vg )93cmp)eezer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performanch+eyuwi)88me iyd *m1e of 5.0. If the temperature in the kitchen outside the rem uew ymihy 8*i)d+e81frigerator 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 ke 4d,-hy pyr0 rfj2mt,qep 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 atjhj yss1z6/9k 0$^{\circ}\,C$ can a freezer make into ice cubes in 1.0 hour, if the coefficient of performance of the cooling unit is 7.0 and the power input is 1.0 kilowatt?    $L$

  An ideal (Carnot) engine has an efficiency of 35%. If it were possible to ) x, ;rp8b2u d+mtlwanrun it backward as a heat pump, what would be its cxt)+ ;a n8wpbdl r,um2oefficient of performance?   

  What is the change in entropyht15.8cy ddgm ey3ep: 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 f 5(la la0ik 8-evvnu.from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entn8al1 zf(.fmkmam2m( i;: bzoropy 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 initial speed ofz u 7)m;ngg,gz $3.0m/s$ 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 7c6* z, -amq cop9 lg.eisxts zwv*85rjust before striking the ground and coming to rest. What is the total change in entropy of the rock plus environm8 .w7ascm59,-qtsexirz6* lo * gzcpvent as a result of this collision?

  An aluminum rod conduvx92h s,yc (v*xzl4w:m xo v(rcts $7.50\,cal/s$ 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 3yas4t 5+ lej(y0$^{\circ}\,C$ 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 alum:k1j)vp 6*qoov7rcr f: s0zveinum 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 K and l/ oflj(n /7*pyo.lew650 K produces 550 J of work per cycle for a heat input o(y.e7*o l/l/fwjnlp 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 elsh uqli6)o9;u:0b-dwg (h otwo 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 hands in order of increas q:yzr , 2fojt. 8nx-;gbqqi7fing probability: (a) four aces and a king; (b) six of hearts, yj2xq7nz;rtf.o:q 8fbqg-,i 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 microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and drop the7*jvbel4z9 xs m on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probability of obtabz7xs4 9 el*jvining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of electr;w,mj iec: 1elicity per square meter of surface area if directly facing the Sun. How large an area is required to supply eje,m:cl;w1ithe 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+ /u) es+pvoqm pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water s m/+ vpqe)ou+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 z+opvgz ya, 4.) ka/oa w)4skelake created by a dam (Fig. 15–27). The water depth is 45 m at the dam, and+z4) yo4 oz)gpsak,aa /k.wve 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 a7ph*c su jqwjajc+ :im 0b 7f00slyl).n engine 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*:b ly )0jqccsi h7+70ja .fu0psmjlW 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 and eu5:0j aqs2uajp)5 fp delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles per second, 5u f2 0qus)e5pa:pjja
(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) absorbd8 vhuk*+ g4iys heat from the freezeru* k48ghv+dyi 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 heatjoz2wu1a8 vn ep )8budcxdy4qx) k)-+ engine could be developed that made use of the temperature difference between water at the s w pevn b1c+o8y-au4u dd)j8kzx)x2)qurface 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 opposix:k* h;t1gvpen.8vkr te directions when they collide and are brought to rest. Estimate the change in entropy of the universe as 1v g:pkek nx8*ht.;vra result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cu p1h:sesw: zygji2 )m8p at 15$^{\circ}\,C$ is filled with 140 g of water at 50$^{\circ}\,C$. After a few minutes, equilibrium is reached.
(a) Determine the final temperature,    $^{\circ}\,C$
(b) estimate the total change in entropy.    $J/K$

  (a) What is the coefficient of performance of an ideal heat pump that extrh;lfrk(,j:se g z m5wu.e1r/kacts hs1(k/ jke gwr5.;emflz:hu, reat 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 j. akz6i ;5vmfcar 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 operatmbz b efh26yt0 8mwd(d7vp:d a,(.tyting 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 s1 gvk81ey wty5tate A to state C in Fig. 15–28 for each of the follkt8gy5 e1w1vyowing processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Cooling tobyp pux2ph; hxcv +,g ef/;5r2wers are used;;fy+ h/x xpevp5c2phgr2 ,bu to take away the exhaust heat.
(a) If the air temperature is allowed to rise 7.0 $C^{\circ}\,$, estimate what volume of air $(LM^3)$ is heated per day. Will the local climate be heated significantly? $\approx$   $km^3/day$(Round to the nearest integer)
(b) If the heated air were to form a layer 200 m thick, estimate how large an area it would cover for 24 h of operation. Assume the air has density $1.2kg/m^3$ and that its specific heat is about $1.0KJ/kg\cdot\,C$ at constant pressure.    $km^2$

  Suppose a power plant delivers energy at 980 MW usi1(skk,+eie z4dv dlj wb-w/h 5ng steam turbines. The steam goes into the turbines sukzdwsv1we4d/ (hk+je - l,5bi perheated 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 operates9yolh ty:.w(8c wla3lz17eje at about 15% efficiency. Assume the engine’s water temp9a.7ec(w1e wztl lhy8:j3yo l erature 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-nnmun6q1c5j**/ (3gqpz tdw tsectional 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 res2jiyelm /8y 6kf;(ids ults 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 tempephvvz8*9e22 d.k jvvq rature 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 essentiall3s ( uhxc.jxd1c 8.bl3+kdlndy a “refrigerator with an open door.” The humid air is pulled in by a fan and guided to a cold coil, where the dc3 1. + su3n cxxb.hdljl8dk(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