What happens to the internal energy of water vapor in s)d2)l+ t59t rwqg4v+e ksdiythe air that condenses on the outside of a cold glass of water? Is work do9ttyd) sli4w+s+q52gerv ) kd ne or heat exchanged? Explain.

Use the conservation of energy to explain why the temperature of a gas inc,pe6a hf/8g mbreases when it is quickly compressed — say, by pushimhf 8pba,/ 6geng down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is done/nqsmmvm5r :k,dgo r 5.ikb+x2an8 +ph sk 4h( by an ideal gas. Is this enough information to tm 5r28qmn,b4 kpks+s k dh:xh5a/ gmvorn(+ .iell how much heat has been added to the system? If so, how much?

Is it possible for the temperatg::1k 8;reccnvt) rh ryy7 ;fhure of a system to remain constant even though heat flows into or out of it? If so,; thh7:n:k r fcre;18cgyryv) give one or two examples.

Explain why the temperature of a gas increases when it is adiababyai g+s27cnv1 c.n f(tically compress1nf (a72 ncgivbcs+y.ed.

Can mechanical energy ever be transformed co eqcwe-ee4u4c05(6ja4 qc xot mpletely into heat or internal energy? Can the reverse happen? In each case, if your answer i ejw5tc- q cu 60exc4eo(e44qas no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven door ope+fasj +jqpox;c/ +a 5mn? Can you cool the kitchen on a hosaq/f+oc j;5j xa +mp+t summer day by leaving the refrigerator door open? Explain.

Would a definition of heat engdlc/3d wu12d gbyevb:jb ic95 c7rf,6 ine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperaturdpm 9z*58tw 0sro 8ofee and low-temperature areas in (a) an internal combusormd8* 05e sowpftz 98tion engine, and (b) a steam engine?

Which will give the g e;+ .css3kdwruq1w8o32dvih reater improvement in the efficiency of a Carnot engine, a 10d3ik hr3 dq+u 21sews8.c;w ov $C^{\circ}\,$ 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) eu(- md74vtr4gpf mo;xnergy. Why, in general, is it not possible 47;(guvmx4 p trd-omf to put this energy to useful work?

A gas is allowed to expand (a) adiabt bgpna, j3+mj+eyd6/ we/ s ilj4ev07atically and (b) isothermally. In each process, does the entropy increasenj gaim/43jl6+/y,esp7wetjb 0e+ v d, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabatically oytm8gym m9w 8:j3z,u-w loy8al2lu8i r isothermally. Which process would result in a greater change in entropy? Explamzg8mla3 9 8ly oyyu l-jt:2,wm 8uiw8in.

Give three examples, other th(+/,tbff7l m ytn)bpean those mentioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discunf mbyt,7b+l / f)ep(tss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 kgg adxsw3 3(9ng of liquid iron? Whygnsa wd 339gx(?

(a) What happens if y:wamuez4b ;;zzn2 8 acou remove the lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) :awu2bz 4a;z8 en;zmc Can you think of two other examples of irreversibility?

You are asked to test a machine zrzupi7d -c 8 uke,5gzv2t l++that the inventor calls an “in-room air conditioner”: a big box, standing in the middle of the roozut2+ +p 7cu-k l, gvz8reid5zm, 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 thosew, xitptk o 7.x (z91z-(rxftx already mentioned) that would obey the first law of ther,ztr w(ox9( .t1 -i fx7ktxpxzmodynamics, but, if they actually occurred, would violate the second law.

Suppose a lot of papers u s/4.l*4 xv oxcb/ ptys+uls;are strewn all over the floor; then you stack them neatly. Does this violate the second law xlv /4uulbct4 o /+ps; .yss*xof thermodynamics? Explain.

The first law of thermodynz4/ kfxkv6a+famics is sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’t even breakfa4/zfx +6kvk even.” Explain how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because ihha7io9t v es+-;7 xpmt tells us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that wouh a7pt7soxi-;vmh 9+eld tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simple food moleculesw xk b4.debdyyo: /8x. into a complex structure. Is this a violation of the second law b:x e wb8dkoyy. x/4.dof thermodynamics?

  An ideal gas expands h0psr8+b) d bnisothermally, 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 fk*s l/, lp1gtnq6 +mxdrictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the vq t*sll ,+m1gx dn6kp/olume 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 volume is halvlj+ 0 +j;o,wzvgh ua.,zeuo (ped, and then it is allowed to expand isothermally back to itseu+;gvuo.hw+( zjz jo,p ,0 la original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas atfsc k6 d;(gid . ia*f(7vy+ypp atmospheric pressure are cooled at constant pressure t fvdaf.ig( * y c+si7ykp6dp(;o a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the original pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is f,n xo l0 bmh--42wvjballowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, and lastly is-wovmh0b jb4x 2nl- ,f 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 ide5lzo)+1k(f tdo sze)cal gas is cut in half slowly, while being kept in a container with rigid walls. In the proceszoso5c ) lde(f1tk)z +s, 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 hala5by k 5s-;gjujry7p3 f its volume. ug5jks53;- by yr 7jpaIn 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 olw gl0c1f m/c/7 f ;zrxoeu5m3f 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until the temperatu0cuc ;ge3rm/ l1z/xm fwfo75lre 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 monaty);i(rcy 0,ypy.v7. dtio w ceomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the0cwy yytv)pi,cr.(.y 7id; eo gas during this expansion?   $ K$

  Consider the following t, c4oi4bgy: eowo-step process. Heat is allowed to flow out of an ideal gao4i,go 4 :ebycs 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. 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 ofh 67 wpr)y20 z,imdz8us yt.bl a system containing 1.35 moles of a mona8yrt 6 20zmuh.i y)zls7wdb, ptomic 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 cuu3x*5 (cpba2ycqo oy1 rved path in Fig. 15–24, the work done by th q(oco*uyx ay p21cb35e 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 swn*ae(o 1 b;x7z4f twxsa5hz ,hown in Fig. 15–24, 80 J of heat leaves the system and 55 J of wor5b7 awwt4 x zofe,;a*1zxn(sh k 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 trhwj f7vaa /cs*,h06 gfansform if instead of working 11.0 h she took a noontime break0 hjv*/ f 7gcws,afha6 and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who u,li8s,apkm z 08 ds1vsleeps 8.0 h, sits at a desk 8k,m8 8i1z,svul p0s da.0 h, engages 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 slepb; (l:yx,xe)ak 3rcueping one hour 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 that3keb x);p, xcy( :lrua 1 kg of fat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhaust)xonfd903 ek h:0nnuws 8200 J of heat while performing 3200 J of useful work. What is th3nnh ed0:)9xkfow0nue efficiency of this engine?    %

  A heat engine does 9200 J ofj/ -b c2fpyy+j work per cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the efficypfyj /2b c-j+iency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temperatures afd)9j0j a. nyfref) y0dn9. afjj 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperatuty .6+(j zzqw3 gliy9kre of a heat engine is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operates at 75% of its maximum theores4)q gkj6;o ettical (Carnot) efficiency between temper)qg6 tk ojs4;eatures 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 ho7(9wff rzu 6r yogbm4u-nzn112 k euc2tter 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 temuw11rey- g422kzubn of97ucrmf(6 n z perature (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 using 680 kcldwnbxs b2.(nl bh4y(2g yi:)al of heat nl s2xbyliyh 2b4:d.() b(ngwper second. If the temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operm.kk:( ,km5* wliy vtnating 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 out 550 MW of electric power. Estimate the heat disch uh.0-zbkju wzp27 b u))jtrh9arged per second, assumi9 hz)u2tzbjju 7-br. ukh)w0png that the plant has an efficiency of 38%.    $MW$

  A heat engine utiliz rm ) f.;a34cgrgn;ooses 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 exhausts ipa-c0nl 3dhw8ts 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, steam engines work in pairs, the output of5rnmd- +tsmju+o6jfsh7( - op heat from one being the approximate heat input of the second. The operating temperatures of the f-fh(p7us jj+s5 r-m ot nod6m+irst 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 is-:+7r(;b1 x4gosz bge,tincz q(fe nc -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operatescoa- w4v2d1o l:byf-o with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5.0. If tez x)12q- hzkwhe temperature in the kitchenz2qh)-e w1 kzx 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 house warmrqyf o 25iugmfpq92m/q)6m1p 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 waterhvo0lg*)3r*8h ps kszzu 3,fc 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%1/vx orvujhf 8q5ot3eew)*o* . If it were possible to run it backward as a heat pump, what would be its coefficient of perfor15*o jo wotq ehv3u8/v x)*rfemance?   

  What is the change in entropy of 250 g of steqy7;m 2nx7af 5w1m zczam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water k adl)vknx: 4fxr/):c is heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change imliom4 0hf1w8o3u p 5yn entropy 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 initi nip4j)/nnzj /,p3b hral 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 eno7*t7b ;gla*b dojb7cergy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment as a result of this collisio;t7cablo*bob 7jdg7*n?

  An aluminum rod condek4e5ho) jhdoov.x gjodrp.9mv 06;7ucts $7.50\,cal/s$ 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 3dw- 78e *bekqril/1yf0$^{\circ}\,C$ 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 ev8gvguag; b2z: 0k h53ph/rlat 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 produ5irx.p l00mt vces 550 J of work per 5 0xivltp0m.rcycle for a heat input of 2200 J.
(a) Compare the efficiency of this real engine to that of an ideal (Carnot) engine.    % of ideal(Round to the nearest integer)
(b) Calculate the total entropy change of the universe per cycle of the real engine.    $J/K$
(c) Calculate the total entropy change of the universe per cycle of a Carnot engine operating between the same two temperatures.   

  Calculate the probabilities, when you throw two dice, of obtaining mabc/.3dm . iz(l/ng q
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hands in order of increasing probabilityeodeaaf n5)qd5 o/4z 6: (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 d5 ndq/zoe4f6)aoa 5e) 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))yql b1k.lm- ,b vwdb hrbr*( your hand and drop them on the floor. Construct a table showing tw)dh)*mblr(q.-bvk ,b1 blyrhe number of microstates that correspond to each macrostate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can dx 3,ge(xxkl* produce about 40 W of electricity per square meter of surface area if directlydx* lk,xeg3( x 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 storedb s/5ypdma e)j 7;(jwsrrpq(a+(yc8o for use during peak demand by pumping water to a high reservoir when demaa)soj(8(csb7dqra /5 jy+m ppy;r(wend is low and then releasing it 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 artificixwl,uyv0llvy/, *4e ial lake created by a dam (Fig. 15–27). The water depth is 45 ,/yxe lwuly4ivv 0 l*,m 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 designed and built an engine that produces 1.50 MW rm +1z*kp5fud of usa* d+up15rzmf kble 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 an efficiency of 0.25 and delivers 220 J of wocmeze.v8r 3.q5wk2+ dsrhl: ark pe2:sh .v3 wkle zrad8mq .5r+ecr cycle per cylinder. When the engine fires at 45 cycles per second,
(a) what is the work done per second?    $ \times10^{4 }J/s$
(b) What is the total heat input per second from the fuel?    $ \times10^{5 }J/s$
(c) If the energy content of gasoline is 35 MJ per liter, how long does one liter last?    s

  A “Carnot” refrigerator (the reverse of a Carnot engine+czpx u5/t* wv) absorbs heat from the freezer compartment at a temperature of -1 up5v*/ t+cxzw7$^{\circ}\,C$ 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 bl4f .wvbce fbg*5 (7zengine could be developed that made use of the temperature difference between water at the surface of the ocean and tfzg bef5c(4*w. blb v7hat 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 wh31rd c3xm tiww 68ayq*en they collide and are brought to rest. Estimate the change in entropy of the universe as a resultmcw xa qd*86r1t y3w3i of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup aw/rx.(9,cth j yl- irzt 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 extr4kyz/b 4mvgpb uv9x0z 13y:; idy+y gnacts hea 0y493 ip;zybx y:g v4 yd1bgunvk/zm+t 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 car refrdwm ck;5e(cnr5xrw 06 krl 7;m9k*mleases 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 temperature o yi6a q)j 6kxar-)gsd40v:auo w,h 4 utku9z9$T_L\,=\,20^{\circ}\,C$ 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 g.z;rbp i.,pvf+ 76tzr: ernzto state C in Fig. 15–28 for each of the following proce.r z;.r r btgp:z7f,eizv 6np+sses: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power planllsm) -csu;yroi 9+ 8ct puts out 850 MW of electrical power. Cooling towers are used to take away the exhaust hea9yluo8l i sm-+sc)c r;t.
(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 turbin ai1 imh5fs1/ees. The steam goes into the turbines superheated at 625 K an5esfi / hami11d deposits its unused heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine.
(a) If the river flow rate is $37m^3/s$ estimate the average temperature increase of the river water immediately downstream from the power plant.    $C^{\circ} $
(b) What is the entropy increase per kilogram of the downstream river water in $J/kg \cdot\,K?$    $J/kg\cdot\,K$

  A 100-hp car engine operates at about 15% efficiency. Assume the engine’s 4-e.e ioj uy0vwater teme 4i.uj0oyv e-perature 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 ys.6 mi6dsm /,s-tcvg 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 resulnl *59pqo2e6 kvssrxxc 0b+1yts 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 tempedf(;8mxs6tebv e8fs 3 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 essentially a “refrigerator with an o1g x04g+w 9wwslk vct+bcw9m r.y,k k0pen 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 dehumidifierxy +,019m4k9 gr.+wcglwv k bwwtk0sc, 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