What happens to the internal energy of water d dmcs) i5z8sz)u7a4/7uqjoa vapor in the air that condenses on the outside of a cold glass of water? Is work do az8o5)au jds4ud /7mszqc7i)ne or heat exchanged? Explain.

Use the conservation of energy 96snbpk)j:ue to explain why the temperature of a gas increases when it is 9jpkeu6:)nbs quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by an ideal g+;0wsa d.opjci.d 5 wlas. Is this enough information to tell how d.l wo;5p.wjc+ 0idas much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system to remain constant even th 3t47 eitm8k+b6azw h dq+:gthough heat flowth64q mieth t: 8wzk +a73+bdgs into or out of it? If so, give one or two examples.

Explain why the temperature of a gas incrn gymjwya4(l., fr5b n8fj /yt 98mi;veases when it is adiabatically compress t,8(j v fyy8imfgy;wj9/.anmlr5n4bed.

Can mechanical energy ever be transformed completely into hea5 glvsz8r x)n4t or internal energy? Ca4l8 n)zsv5xr gn 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 ov un/(l tm9,x1f8ml aopen? Can you cool the kitchen on a hot s,(ul1lvoa8x9/t nf mmummer day by leaving the refrigerator door open? Explain.

Would a definition of heat engine efficien)9 u5y 6ci8eyge 5z4t h;uqkkncy as $e=W/Q_L$ be useful? Explain.

What plays the role of hi hbts41egb9swv 6pey)z5a 4n2gh-temperature and low-temperature areas in (a) an internal combustion engine, and (gv19y 4 h)ne b p26a4sbst5zweb) a steam engine?

Which will give the greater improvement in the efficiency of a Carn2kv;m eb r5zbc0 e( ukl,s8di(ot engine, a 10ber0bk(lvcu,ked;( s 2im z58 $C^{\circ}\,$ 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) ene4fssx .: (8fsr4oz2c/qh i awjrgy. Why, in general, is it not possible to put this ens h24x/w:. a( sc fzjs8rf4oqiergy to useful work?

A gas is allowed to expand (a) adiabatically and (b)o 1mnvd /hd v.xh3,he; isothermally. In each process, does the entropy inc o,dvheh dmvh.;nx13/ rease, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabatically 5q hvsd m;qmmyw8-xi;9makzrs. 6r44or isothermally. Which prv; rr4-im5q6km8.9s mhmwzqd 4ay s;xocess would result in a greater change in entropy? Explain.

Give three examples, otnp:m*x zdfkt7iae8)3i b. j*cher than those mentioned in this Chapter, of naturally occurring processes in which order goes* * dbf7jixzea)8c3:tn.km ip to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid irowes, 2 8yftdu)m+.r s5vl- rrzn or 1 kg of liquid ivsurr2 t . m)zl-s,dr+w8e5yfron? Why?

(a) What happens if you remove the lid of a bottle containing chlorinoalp-ib8k8- se gas? (b) Does the r8pk-io ab8l s-everse 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 ca*s;g sr+/8k )cftfhlj lls an “in-room air conditioner”: akc8 frg*st+hs/ f ;)jl 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 coming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than those already mentioned) that would obey b icy. j-p1zi- sfn(r.the first law of t(n-jpy. rib1zi c .sf-hermodynamics, but, if they actually occurred, would violate the second law.

Suppose a lot of paper x+xqtnbb7xz ;(/z0p ps are strewn all over the floor; then you stack them neatly. Does this vio /bx 7bx xn;0z(zpqpt+late the second law of thermodynamics? Explain.

The first law of thermodynamics is someti6pw/zmf je* y8mes whimsically stated as, “You can’t get something for nothing,” and the second law as, “Yow* 8y 6jf/pemzu can’t even break even.” Explain how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” hv8zu;sm, 9kh because it tells us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that would tell you that time wa9mzh,k ;uhvs8 s “running backward.”

Living organisms, asn6opzu /0z1n y they grow, convert relatively simple food molecules into a complex structure. Is this a violation of thnn6/z1uo p0 yze second law of thermodynamics?

  An ideal gas expands iso. zk;mt8b:yjatmf1 1fthermally, 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 withm+a;vmzz5mt cvjsh tb*2w 1je 0/p;v6 a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume i tm;bm+tvp6hs2vz e; w jza/mvcj 50*1s 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 halved, an c2- t a;yfij*4-lx6hdf hn)jfd then it is allowed to expand isothermally back to i* fh-d)j cjai h-2;lf6f4t yxnts original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following procjiho, qvl s*9 .y;33:srmmveoess: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.,o 9: *sv vi o3lmey3jsmqh;r.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 (absolngg,cg2mbac;55 u wk t4*cj:c th c8w5ute) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pres5*t ,c5:hgtw;cg ccajn42b5wukg 8cmsure 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 slonylay*x2a or3p a2:;kwly, while being kept in a container with rigid walls. In the pra 2l:2pny*aa;3o rky xocess, 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 almosta kig(8wua4. n ideal gas is compressed adiabatically to half its volume. In doing so, 1850 J of wou.agwn8i (4ak rk 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 f ,sh(/jde 7mekrom 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 temperature reache md,kj/e7sh(es 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 m*k ve,v:b-cc an ideal monatomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the gas during * cc:k-b ve,mvthis expansion?   $ K$

  Consider the following two-step process. Heat is alloskqtgq:t + 2r1wed 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 value1qk s+ tqtrg2:. 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 conw:qs6nnk(7x h taining 1.35 moles of a nx (6:qksn7wh monatomic 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 path6cft4.gq;bd a1)d a zao v1/do in Fig. 15–24, the work done by the gaa4d.v16 ;caofo)gt qb1/a d dzs 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 alon0 md1n3jceme)g the curved path shown in Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on the e jcn mde1)m30system.
(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 tran:zlz8so t :pb3sform if instead of working 11.0 h she took a ::3zptlzs8b onoontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average /rey/fnc t(y- metabolic rate of a person who sleeps 8.0 h, sits at a desk 8.0 -nfr/y/eyct (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 sleeping onew:j+ak s; /7io4(bwyqsyk r) b hour less per day, using the time for light activity. How much weight (or mass) a ojb /ws7+bs;kwr)ikq4(:yy 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 energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J ofd0o7 ry;ad j hx9uha;9 heat while performing 3200 J of useful work. What ;do07x jhrh 9aadu;y9is the efficiency of this engine?    %

  A heat engine does 9200 z/nf*sz et,ygr-7z9f 6erdy- J of work per cycle while absorbing 22.0 kcal of heat frnzrtd fs6g/- y79f ,zrz-yee*om a high-temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose opxky :8d0t +myyerating temperatures are:ky+m xt8dyy 0 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperat lym24n p6 n-f9z./pzksa kk5jure 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% kax v2wm6i7k d/mg q,1of its maximum theoretical (Carnot) efficiency between temaw,x6k1ki q7dmvm2 g/ peratures 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 fbrjokntxby 5:gta*t 320 t*2hotter 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 nitrogen “fuel” (Fig. 15–25)? y3bbr a*nt0jo:tt*f gt5x2k2    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW while using 6o,dux-2ng x4 p80 kcal of heat per second. If th2p-d xnx 4o,uge temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatures are rcaksz;3c jdj6( i4e 9210$^{\circ}\,C$ 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. Estiamvb.,16vgu zmate the heat discharbvz 6g.av1 u,mged per second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a bb x:nd34cnwv1 ih7lfp+v 8:g 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 itb /v xtpmf-o5.s 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 ja, 6rdy*u t*qw+kf/ wpairs, the output of heat from one being the approximate heat input of the second.ut*d k,6/ wq+frajy w* 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 freezer coolinat.do+/c5h9 ds el,y jg coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates with a ri9nl sb+46m z bby870kn oll ob);w2hin a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of k hqn- b+at1/ihk;yc78q -z cxperformance of 5.0. If the temperature in the kitchen out7-i ;cb/khx ak hy+q- n8qtc1zside 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 warm at 2kb6mo i t65dbj94b,ip 2$^{\circ}\,C$. 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 ag dyxyd6)sw(,b(6r(nblhh8 g t 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 we iwm2ch10m d..8h nczsre possible to run it backward cd 8z. csm0iw.hn2m 1has a heat pump, what would be its coefficient of performance?   

  What is the change in entropy of 250 g of steam at 893 2 fowebidvdip )/c100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is 3vist(yk g947hfsf 3 rheated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in * vj,dz3tt kldyooa4l /i +;+pentropy 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 s2ccf 1u*a3 eet42 cgwkpeed 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 0sr2 lmwc c5(g3i3c4uwxse/j energy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus en2e (4x3mslg3wcsc u i0c/5jrwvironment as a result of this collision?

  An aluminum rod condu03 wfe2 kk ggq9.cqn2 +8thmzicts $7.50\,cal/s$ 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 3p7y3)8 a; ohoehs p0cc0$^{\circ}\,C$ 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 aluminc/zpot:n9 xjdl- f ;g+um 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 650 K pr*s cll z(2m7m rcp-cn/oduces 550 J of work per cycle for a heat input( nc*csclmzmr lp27- / 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, whenq dxzf,4p b517f2hg52z nsjc j you throw two dice, of obtaining
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hands inc g+ ;cf3b3gwx 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,;wx+gc g3 fb3c 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 s53tfq5g 1copg dm,2gnhake six coins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspo 1g5gtcqd o,pg m3f2n5nd 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 produce about 40 W of electricity per square 24cmvj)vd,us8ng 0 r,zq 5avwmeter of surface area if directly facing the Sun. How large an area is requirem,v 8,s0g)qjwruv452dv acznd to supply the needs of a house that requires $22k\,Wh/day$ Would this fit on the roof of an average house? (Assume the Sun shines about $9h/day$)   $m^2$

  Energy may be stored for use during peak demand by pumping water t hecsmi 1+zb x,32*nhqo 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 the tu13+bh, qsex c hi2mn*zrbines at a rate of $ 1.00\times10^{ 5}kg/s$ for 10.0 h at night.
(a) How much energy (kWh) is needed to do this each night?    $\times10^{9 }W\cdot\,h$
(b) If all this energy is released during a 14-h day, at 75% efficiency, what is the average power output?    kW

  Water is stored in an artificial lake created by a dam (Fig. 15–24mrf.i skqp(;vupojn g655z .7). The water depth is 45 m at the dam, and anrqog kuvsj4..5; (pz56ifpm 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 cmfg8sd 6ni t 9 ht)uvd;9ua9(designed 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 rejecting 1.50 MW of thermal energy at 215 K. Is there anything fishy about his claim?si v9m u86tgdn)t u9(ac;df9h 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 09v;zt8u 6;7h/ :d swp: yick2:lzdodc 5oqsac.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 ctow;uc2ov6: c iz:;sdk chzld 7 ay5p9 d:/sq8ycles 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 (th 0cotptn7zz: p01+48 durn smve reverse of a Carnot engine) absorbs heat from the freezer compartmens :mvznod8r4 17tczpt 0nu+0 pt 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;a wi22)wbocy1c :a erloped that made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, theowabw yi:2)racc; 21e 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 wh:s0aq40 zebb ken they collide and are brought to rest. Estimate the change in entropy of the universe as a result of this collision. Assumes0bk04aqb : ze $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum c r77jtib)bu-le4 ;yvyup 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 wfp:m 2(hi0*l+sc arbof performance of an ideal heat pump that extracts heat from (hw:aslr im* p c+f2b06$^{\circ}\,C$ 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 releas9bsc-at:g8 h egni 51bes 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 temperaturw1e -d470e b; +ugoin38xqdzd nrm*g fe $T_L\,=\,20^{\circ}\,C$ 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 to state C ienu13 oyxh 1,dn Fig. 15–28 for each of the follnu h dyeo13,1xowing processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant p jg(or(pjk)cypla. 2 6uts out 850 MW of electrical power. Cooling towers are used to take 6cljp( ).rjo(k2gya p 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 using steam turbia/wk( m4a1 xvxnes. The steam goes into the turb m(4w1axxa/v kines superheated 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 operates at about 15*,) u19 :rje miexnbua% efficiency. Assume the engine’s water temper rmu9ej)e x*b:a,iu1 nature of 85$^{\circ}\,C$ is its cold-temperature (exhaust) reservoir and 495$^{\circ}\,C$ is its thermal “intake” temperature (the temperature of the exploding gas–air mixture).
(a) What is the ratio of its efficiency relative to its maximum possible (Carnot) efficiency?    %
(b) Estimate how much power (in watts) goes into moving the car, and how much heat, in joules and in kcal, is exhausted to the air in 1.0 h.P =    W $Q_L$ =    $ \times10^{ 9}J$ $Q_L$ =    $ \times10^{5 }kcal$

  An ideal gas is placed in a tall cylindrical jar of cross-sectional ar-)x2 gfyy1u 2 fxhzq3fea $0.800m^2$ A frictionless 0.10-kg movable piston is placed vertically into the jar such that the piston’s weight is supported by the gas pressure in the jar. When the gas is heated (at constant pressure) from 25$^{\circ}\,C$ to 55$^{\circ}\,C$, the piston rises 1.0 cm. How much heat was required for this process? Assume atmospheric pressure outside.    $J$

  Metabolizing 1.0 kg of fat results in about 2cu( - g,9a:duuvsnm.2r gxwu$ 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 temperaturn *1d0;h .q daj-krmsfe 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 “refru q1*dezwd m:) ruu,1ligerator with an open 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 temperatqeuz1*uw: 1dr,)umdl ure 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