What happens to the internal energy of water vapor in the air that conz-gcg+uk05 ee denses on the oug -5cz k0g+ueetside of a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain why the tema) eb6wk(md )nu nndo fd/7+6fperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder —)mnf()n /6+adknb6def7wud o whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by an ideal gas. Is this enr; /fgf 2m4q0 xeaanw4ough information to tell how much heat has been added to the systef e4x2/afga0rmn w;4q m? If so, how much?

Is it possible for the temperature a lu 8pfz d22+a8i7 oj.xyu0ajof a system to remain constant even though heat flows into or out of it? Ifoxadfjua22zp7+ ju il.y88 0a so, give one or two examples.

Explain why the temperature of a gas increases when it is adiab6 7gwl2k)fise atically compressedk il7efw26)gs .

Can mechanical energy ever be transformed completely into heat or internal enervw 6)zwoxnq 4;gy? Can the reverse happen? In each case, if your answer is no, exzv 6nx)o4w;q wplain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leavin s+3nj -zc l7h64pni;ikd/wtng the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door open? Explain67nj;sndlth nc4i-w z3 p /k+i.

Would a definition ofgoo+/// rqm fi heat engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature aread(0,d 6fnyia as in (a) an internaf,n(yi60d ada l combustion engine, and (b) a steam engine?

Which will give the greater iavm2v,zek8g :mprovement in the efficiency of a Carnot engine, a 10 8v2g:mk ,avze $C^{\circ}\,$ 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 (internal) energy. Why, i -aomnmnjt*sfje2g4d 9ct 39yp) +a1in general, is it not possible to e-tof14m9 na*+)dsipc9a gjt ymn 23j put this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) isothermally. In each procfzu. ,t9(ksj less, does the entropy increase, decrease, or stay th, .ju(t9zfkl se same? Explain.

A gas can expand to twico .9h1cxjtz0p xu0l7c e its original volume either adiabatically or isothermally. Which process z10.9cxcu70tlo x phj would result in a greater change in entropy? Explain.

Give three examples, other th o7-5msk 4api0nz u/yban those mentioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the observability of theuk0 sz -/7nb5pomi4 ya reverse process.

Which do you think has the greater 9g.;i 3(og:jgnk7w /vykrehlentropy, 1 kg of solid iron or 1 kg of liquid iron? 7ohr9 ; l:y(i g/ jekwg3g.vknWhy?

(a) What happens if you remove the lid of a bott9 . oooo5z)ifqle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples 5.izof9oqoo )of irreversibility?

You are asked to test a machine that the izs8x 7 :km/ c*z-ppofnyy(o7h nventor calls an “in-room air conditioner”: a big box, standing in theozo 77n(: s ym-zfhy8pc*/pkx 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 those already mentioned) th9pnjdj.l 7 -pyat would obey the first law of thermodynamics, but, if they actually occurred, would violate the secondyp 9 j.n-pldj7 law.

Suppose a lot of papers are strewlcn*ri agp u3u xf)45de.71/2bfj vyin all over the floor; then you stack them neatly. Does this violate the second law of thermod2d71frfi ibe*y 3u5x.lpc4) n /vgjauynamics? Explain.

The first law of thermodynl /v)k v xudirn15/zs )yit55gamics is sometimes 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 equizlrdu1igs) y5vkv) / 5/x nt5ivalent to the formal statements.

Entropy is often called “time’s arrow” becausvsutb ct2iw50 cga9g*qv + 5pw4z1b0fe it tells us in which direction natural processes05wg25avgctbztwsb+ vu9 f4p iq1 0*c occur. If a movie were run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they growy)9ys/nq9aozvz hk :n(1q )ae, convert relatively simple food molecules into a complex structure. Is thiay)9z/oyq v( qn neaz:hs91)ks a violation of the second law of thermodynamics?

  An ideal gas expands isotherma*k cs(vs+*rk / skin,.k2 u1lgx( croclly, performing $ 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 pistonz7n)l(i ve3h u,w pno6 and maintained at atmospheric pressure. When 1400 kcal of heat is added to6)neu7nvi ph,lowz(3 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 ir7l)i05bapkj ts volume is halved, and then it is allowed to expand isothermally back to its pr)7i ljk0 5aboriginal volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2;d65-h g0dul 6c/rdii: :qz)tsjre ki.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isotherqi/z) -:6sdlde5ud kric:g0thr 6ij;mally 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) pressure is allowed0sxcdu-36n y j to expand isothermally until the pressure is 1.0 atm. Isn yuc3 6dx-0jt 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 cut in half slowly, while being kept in a contn 5ntjv gug 1q xi*,( +hbqg;ihz4(dx5ainer wit 5tn4nxhv dg b(;h5q g,u zjq+g*(i1xih rigid walls. 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 adiabakp g;98o7sfp itically to half its volume. In doing so, 1850 J of work isi7pp;sfo 8kg9 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 prlm)cx1 q+zfg 4bv9hr0essure of 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressurvbfqm9l+gxh 01 )rc4z e 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 *m8 t8u3*if btk fp,;rdj72+dgw rj rwideal monatomic gas expand adiabatically, performing 75*tjrr dd2;u3p+ rbfmj*8 igt,ww f 7k800 J of work in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is eh6 h1j0agzm8allowed 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 pressu6h hm8j1g0eza re, from a volume of 6.8 L to 9.3 L, where the 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. 15–23 shows two possible states of a system contai*b,8 t1 eeeug*d jwxq8ning 1.35 moles of a mona*1 e,q d8we8 ge*tjbuxtomic ideal gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to c along the curved path in Fig. 15dyzf*o 12v ,+atnlbs, –24, the work done by the yf,s nv,+zd*1b alto2 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 curved path shofdd 7+00kfksfszwdqcv82;1u wn in Fig. 15–24, 80 J of heat leaves th0d8c2 vk s0 7wzf fkq1;f+dudse system and 55 J of work is done on the system.
(a) Determine the change in internal energy, $U_a-U_c$.    $J$
(b) When the gas is taken along the path cda, the work done by the gas is How much heat Q is added to the gas in the process cda?    $J$
(c) If $ P_a\,=\,2.5P_d$ how much work is done by the gas in the process abc?    $J$
(d) What is Q for path abc?    $J$
(e) If $U_a-U_b\,=\,10\,J$ what is Q for the process bc?    $J$
Here is a summary of what is given:
$\begin{aligned}
Q_{\mathrm{a} \rightarrow \mathrm{c}} & =-80 \mathrm{~J} \\
W_{\mathrm{a} \rightarrow \mathrm{c}} & =-55 \mathrm{~J} \\
W_{\mathrm{cda}} & =38 \mathrm{~J} \\
U_{\mathrm{a}}-U_{\mathrm{b}} & =10 \mathrm{~J} \\
P_{\mathrm{d}} & =2.5 P_{\mathrm{d}} .
\end{aligned}$

  How much energy would the person of Example 15–8 .1v4k+v tcfh6:q5 lsuo n1ugttransform if instead of working 11.0 h she tooksutf: h1v+n6c 5 kugtv qlo1.4 a noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who s r5 h cs. )g) xqyd0omj-axx93qxs4q+pleeps 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, anxsh)s)ax + 34 qpj9q 5.xycqogxr0-d md runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per datsg16zj c 2f4cy, 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 stors62c zc4j1f tges about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200b 4xvz v)2bcz8,f5g:ipaux w8 J of heat while performing 3200 J of useful work. What i f c5u8v)ix x:z84,b wzag2pvbs the efficiency of this engine?    %

  A heat engine does 9200 J of work per 8f nvh 2-eshs/cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the efficiency of this engi s-f n2he/h8vsne?    %

  What is the maximum efficiency of a heat engine who-mjimuho. wo 1 visme:73 mi:(se operating temperatures are 580 .o-s:uvim mj73oi:1mmie wh($^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine is:ninzgzv3u 9, g(dxku zi0b*1 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operates ata,vs+ao 7 zt j 6dto66r*,fwtc 75% of its maximum theoretical (Carnot) efficiency between temperatur, w f67a6 avoojtcrz+ st,6t*des 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 hotter than amck6o ,6 .txl iid-j twahlt15cy*),xcbient 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 transferre atc,i 61t.c)kwc *-h,xy6l jxtol i5dd 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 r ne,g8q5a,llc ,vu-pxate of 440 kW while using 680 kcal of heat per second. If the temper8 al- g lxu,p5qecv,,nature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating tempz : ;j7y ;mngmcch+c+vvuo3e. eratures 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 (otzj rs5* ,koelectric power. Estimate the heat discharged per second, assuming that the plants( o*5zor tjk, has an efficiency of 38%.    $MW$

  A heat engine utilizes a epk- 7bj2q 2irkcphaqs/65 h.kov 5u+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 at9+y cju p.v4ni 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, steam engines work in pairs, tbccub: unh7:nv) /9 rahe output of heat from one being the approximate heat cbn/ubca: :r v9nhu7)input of the second. The operating 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 frbxpj-g*v ru4 j54ya5 yeezer 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 operab dtqc*sw:/wb/5ps+ ates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance k-6pzb bri8,f of 5.0. If the temperature in the kib-p6 brk,8i zftchen 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 keep a housbg 20-p9opo kpw/4rbse 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 waterovk,/4c- ,ii ftf-,e)c iwpr u 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) engine has an efficiency of 35%. If it wereijg+ hq fxv4.p2r 2,nx possible to run it backward as a heat pump, what would be 2q ,n.hrp vfg2xj+ x4iits coefficient of performance?   

  What is the change in entropy of 250 g of steam at 10u)mpe(ds ea) lk/i(vz. 7/v ho0$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is henq: zkrq::t+)f s *i t;pldp.jated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy of ym:0gj5+rew )3k dfh v 7y(eef$1\,m^3$ 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 sp8s+x.7 tjqiy( bsql/v eed 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 comig kh-k2z8e y*5qztbgtg94przyb4) +hng to rest. What is the total change in entropy of the rock p2gtph8ht 4yg)qzzkz- eb b4ry9 * 5gk+lus environment as a result of this collision?

  An aluminum rod conductwi j)qg1 af;gl (/5ixts $7.50\,cal/s$ 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 30 656 *dcutfd6t kqk p05inj+dq$^{\circ}\,C$ 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 atv. r71/n i7 mbepnp-u4qb* man 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 650 K produ f+z,y mkll33vces 550 J of work per cycle for a hz +kl,lm fyv33eat 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 thro.bsa fw65atjf9 x9k *qw 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-cartn nx wbo)535td hands in order of increasing probability: (a) four aces and a king; (b) six of tonw 35)bx5n thearts, 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 shaks m8-r / gn*q rhei7v)*qi7nbte six coins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macro*n8 q -e/mh77br t*)sqiinvr gstate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of electricip kr*s(khdj1r-ge )(a *rtd4f14hnwq ty per square meter of surface area if directly facing the Sun. How large an area is required to supply thfn(4krk-)4w ph* *d1tr(a1 d ejhsqrge 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 emh ;)b-mm/blhey;6k*afnq /peak demand by pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Supposy;mhqb6k) lmfhn //am ee-;b*e 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 ansad i pv*y3d i*ob0i) v8a6l2q artificial lake created by a dam (Fig. 15–27). The water depth is 45 m v2idi)p obq3i a8*dv6s 0yal* at the dam, 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 desqx -jk/e4jqwp53o/orw4; mhs igned and built an engine that produces 1.50 MW of usable -/h;qpwmk q5jo e3o4 swrj4x/work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.50 MW of thermal energy at 215 K. Is there anything fishy about his claim? 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 n ;t,j/gfe6edan efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles per second,;et 6,n/df gje
(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 heat fr2gyht7+9han:r;v)l,f rudg;ngrf 7d j47 qboom the freezer compartment at a temperaturg 92uj7vr l )hy ghnta4;f7o;f,7dd nrrg +:bqe 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 l9e :harca kn,7 axp:9be developed that made use of the tempkl 9a r,7na:9e :hpacxerature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars are traveling in opp 8 v2+kjqvska-osite directions when they collide and are brought to rest. Estimate the change in entropy of the universqv-k8j2kav+ se as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup at 1i1 *kijsx9o6- u4hlllyvjn f(5 )hw8o5$^{\circ}\,C$ 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 thati5wn6(bke tqdwcj.3* extracts heat from 6e* b3nw(q5 j.wd6ctki$^{\circ}\,C$ 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 rercu)h +9 y v3+z1q lf-0dq0pptia x1qbleases 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 temperat/g lw2m bvx)t4b34 fqrure $T_L\,=\,20^{\circ}\,C$ 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 s+wp42tadffv5jr *sv9; dx 5whtate A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, a2; dff9p5t* wxsj 5dv 4wahrv+nd (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electricalehtr +y;,xr:tmk) 1x4wdb s p6 power. Cooling towers are used to take away the exhaust heaty+wtdreb 4p6h,xk r:s)tm ;1x.
(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 e9v .fzotfn:1p*tqm p1is b xlt-88iv u.+fqr* nergy 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+fsvrt pt*81fp:.1t.z9b-n8qui*li vxmf qo engine.
(a) If the river flow rate is $37m^3/s$ estimate the average temperature increase of the river water immediately downstream from the power plant.    $C^{\circ} $
(b) What is the entropy increase per kilogram of the downstream river water in $J/kg \cdot\,K?$    $J/kg\cdot\,K$

  A 100-hp car engine operates at about 15% efficiency. Assume the engined)skk3z ynr ;0/wjh g7’s water temperature of/ngk) zhrw jsk ;703dy 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 placek)w-giyd/vjtyj2y ckz72j+koa9p5/ v ye,n 1 d in a tall cylindrical jar of cross-sectional area $0.800m^2$ A frictionless 0.10-kg movable piston is placed vertically into the jar such that the piston’s weight is supported by the gas pressure in the jar. When the gas is heated (at constant pressure) from 25$^{\circ}\,C$ to 55$^{\circ}\,C$, the piston rises 1.0 cm. How much heat was required for this process? Assume atmospheric pressure outside.    $J$

  Metabolizing 1.0 kg of fat results iy 2* 1ly c *ypgdn1h. o mcbgx:+txmuu,j(td(4n 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 tempe6) igitiy-6g. r.wzqi- m+ok vrature 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 obgof4)( k;ss+fjw c *irdp mj/ee 9-:npen 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. e 4j+fc/sgwo-enbm* f9di kjs;) :(pr 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