What happens to the internal energy of water vapor in the air that condenses o7x-vb voti) (on the outside of a cold glass of water? Is work done or heat exchv7xtbi-(o)ov anged? Explain.

Use the conservation of es hn-fyaq a3w3t ie h)jc-/o4;nergy to explain why the temperature of a gas increases when it is quickly compressed - y;qh33s/o) it4afnw a-che j— 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 idea4g;srwhr rg 5r 1op3s/l gas. Is this enough informa 4 ;/o 1rrghrrssw5pg3tion to tell how much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system to remain const:cio9y9 jlck)ghm4 z, ant even though he)9 gyloicz j mck4,:h9at flows into or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiab:us73efjgv9o )-in;no3 xs vyatically compresse93vi vx:u;)sojo-ys7e gfn3nd.

Can mechanical energy ever be transformed complet lxaa8d-x+: f5r g ,dgsd02bqjely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one orxbx ,jl fd0g-s:d r g+da58q2a two examples.

Can you warm a kitchen in winter by leaving the oven door open? Can.q5; qy bodyn; you cool the kitchen on a hot summer day by leavb; q5d.yonq; ying the refrigerator door open? Explain.

Would a definition of heat engine efficiency asgrus:1en di e2lu0 u); $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temph+(7gl/geol 7 2boxuc erature areas in (a) an internglu/g lc7xo2o(7+h be al combustion engine, and (b) a steam engine?

Which will give the greater improvement in todzt/c2vq q 2)he efficiency of a Carnot engine, a 10z dvqc)2o q/2t $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendoc.k,- -wcab svj8at9tus amount of thermal (internal) energy. Why, in general, is it not possible to put this energy to ak . w9ct,cjv-t-as8 buseful work?

A gas is allowed to expand (apnqw,eswrk /+4-x1) :ji* z, lmyg ycu) adiabatically and (b) isothermally. In each process, does the entropy increase, decrease, or stay the s4x* g+iempyq,j:w,yk/ s1nc uzw r-)lame? Explain.

A gas can expand to twice its original volumeujfb su6(k*x:nuel1rbal 70, either adiabatically or isothermally. Whicsb,ue xl*:a67 kfu1 l0 b(unjrh process would result in a greater change in entropy? Explain.

Give three examples, oth+pe/ tfi)z3w bgmm*f7 fny.b()m) itaer than those mentioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss i fmb)mafmni* .pg))( efzbwt37 y+t/the observability of the reverse process.

Which do you think has the greater entropy, 1 kg ofj g-t /0zhsnus b:eh;;yxr0c ; solid iron or 1 kg of liquid iron?x gzhe0n;us:rc;jby-h0;/s t Why?

(a) What happens if you remove the lid of a bottle conk5djqu 09fyv6taining chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you 0qkfj d96vyu5think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “63 d yn fx1nguui./ 3qumk-;axin-room air conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air coming oui;nfgmuq3 yan. 1-3u6/ dukxx t of it. How do you know that this machine cannot cool the room?

Think up several processes (eih+) ra. btn i.w:36 cowjwu7wdip,)other than those already mentioned) that would obey the first law of therm.tinr.,+)aje wuhwdo3wc i) b7i6w: podynamics, but, if they actually occurred, would violate the second law.

Suppose a lot of papers are strewn all over the floo 9 a/an,plkq;cny.gh3p c: ts5r; then you stack them neatly. Does this violate the second law of thermodynamic:kghlan ;t c3cp5 y ap,9/n.sqs? Explain.

The first law of thermodynamics is spz :nuby 0eez8 a3p.g:tbu4 f:ometimes whimsically stated as, “You can’t get somethi8pu.tb 43zgz ep buf0::nyea: ng 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 called “time’s arrow” because it teleey5rd;4 0o)imoweh(ls us in which direction natural processes occur. If a movie were run backward, name some processes that you might see that would tell you td)o 45;y 0oee(herwim hat time was “running backward.”

Living organisms, as they grow, convert relatively s2.klpg+qiz 4cimple food molecules into a complex structu 2lq+kz.4 gcipre. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performing /l0 1wan0ueph$ 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 cfu bq.koiixx p6u p. qtp664-6ylinder fitted with a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is adq.kfxu - 4i6 .i66opq bup6xtpded to the gas, the volume is observed to increase slowly from $12m^3$ to $18.2m^3$ Calculate
(a) the work done by the gas .   $ \times10^{5 }$
(b) the change in internal energy of the gas.    $ \times10^{ 6}$

One liter of air is cooled at constant prxk9hz,lp-6b bessure until its volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the pro6bb hkp x,9l-zcess on a PV diagram.

Sketch a PV diagram of the follt+:* m, eogt2gae,tguowing process: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume,tg: o*2, ug+amge tte 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) pren;d.n 0lbe cg2ssure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its ini.g 0nc2ld ;bnetial 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 5qq3.vo h8yy-z i e6pd8jv-xdu69 xp akept in a container with rigid walls. In the process, 265j8 5-yi6.d azqov8hp 9-ue3pqxd6 vyx 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 adi9ocf5tf+3pb) ) hmd pv(5shgn abatically to half its volume. In doing so, 1850 J of work is done fp5+m(bh v5d)nh ) 3cfsotpg9 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 attrl:.xg booj 166 v;pi wm20qym from 400 mL to 660 mL. Heat g1tq2rl;y bi:m jw pov0.6o6xthen flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until the temperature reaches its original value. Calculate
(a) the total work done by the gas in the process,   $J$
(b) the total heat flow into the gas.    $J$

  One and one-half moles of an ideal monatomic gas expand adiabaticjkdmjc4o0,ip v9 3d1oally, performing 7500 J of work in the process. What is oi1m 0kjjp439v,cddothe change in temperature of the gas during this expansion?   $ K$

  Consider the following two-sby(48 ma k*,j2pa0bvvl,f n iytep process. Heat is allowed to flow out of an ideal gas at co(f ,2im,pynvj* vba4 bla8 y0knstant 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 twgon ecinog: )5h x9h33o possible states of a system containing 1.35 moles of a monatinn:g 3ecox5h3o 9hg)omic 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. 15–24j:lj 84) u j72wxlyiog, the work done jyj:8)uiwxl 2g j7ol4 by the 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 takinge(5pvxfurx .. a gas from state a to state c along the curved path shown in Fig. 15–24, 80 J .. 5rupvxefx( of heat leaves the 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 ki+yc am 7 83b3g4wreq,6o mrktransform if instead of working 11.0 h she k837k+4orrbeq3ygmm c,aw i 6took 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, sits at a do8k35vpsb+i w p no4,xesk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 wpn38o4,v+xso bi p5kh daily.    $W$

  A person decides to lose weight by sleeping 0 unh+7 u(.db+rb yeuwjm4g5g one hour less per day, using the time for l r+n.duj +ube7mbw4yg5u(g h 0ight 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 energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausq tc*zl c9rej:3dn+:bts 8200 J of heat while performing 3200 J of useful work. What is the eczd+j cq l rbt:*93n:efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle whilew;l jx:43,y2 wbxpynk2 *ypv s absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the efficiency of this engine? pykx,sw ;vl:24 yjp nwx2y*3b    %

  What is the maximum efficiency of a heat engine whose operating temperatures a j 1)-ckygsze) o..0 p1xrzfjkre zyk-prge0j.1)kx ofc s .j1z)580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat e)0uwxqm5 my3 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% oa5 tchsm3+ ,6klgr:y of its maximum theoretical (Carnot) efficiency between tempera+myrhg3, o6 c a5s:ltktures 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 r a*pxhj+;hg2ll,r2q 29av ymambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What wouldll q2h *prh2 y9 ;,mrxaj+gv2a be the efficiency of an engine that made use of heat transferred from air at room temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW while using 680 kcal of hea50,qnmg : mj+md6 vrzjt per second. If the temperature of the heat source is 5j,vgjmqm m r6n0d:z+570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s op2pt 4(r3ywbpferating 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 /w(vv8hwta(iv2aks .uw2 f-jelectric power. Estimate the heat discharged per sech ji/aw wa.kv2 (-(sufv2vt8 wond, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a fsylr qkw- lvq*pdgkyx7 g62h6+m19) 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 ev iajxfox2)j59 ah/969 5g 3sknxrrzits 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 of heat from (b 0c c fhjqj(v3/ymh1one being the approximf by/cc31mq(vj0 (hhj ate heat 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 freezer cooling coilr dpwdf sp;3z*c 8azo/4 1h368cukdz h is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-f6+k,581zye yn nle*be7d vxk kreezer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of pe.b* :*8t koq*6 5q - k,fahe;ef hsz-lxkmiwrprformance of 5.0. If the temperature in the kz hqwk*8a5k*- f,b.ox*e -t skmh 6:eipq;lrfitchen 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 vw 8o05tzzlsf-5bim iem1l )* keep 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 at 04+lmug+u8l d q1g/fgd$^{\circ}\,C$ 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 run)z w8mjp5drg s rc*(7* gntc4p it backward as a heat pump, what would be its coefficient of performance? gzs*rc4wpg8*dnp m )57j(rtc   

  What is the change in entre(uq0u jts7k-u9y 9y3w + xaqropy 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 from . so pw6j w0rad+);w9kzfx w n/u1urs50$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in t- k5p -q--bgzt,ebpilt-4xaentropy 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 in.s p/ i*f(hm,/hdgch titial speed of $3.0m/s$ slides along a rough table and comes to rest. Estimate the total change in entropy of the universe. Assume all objects are at room temperature (293 K).   $J/K$

A falling rock has kinetic energy KE just before striking pli.p:apo0. w the ground and coming to rest. What islpa. 0:piwp .o the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conducmsnilomds cjef*:2 mm(5,u5/ ts $7.50\,cal/s$ 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 .gxz7wps6 *ui$^{\circ}\,C$ 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 aluminu/ttjybb bv.7e; 5s 5vmgfm n39m 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 atqp5nkg,89hdhq 9) b tb 970 K and 650 K produces 550 J of work per cycle for a heat input of 220b q,g)p8 h59t9kbnq hd0 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 ty g b(:+df5d*4ldw phrwo 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-m c9,dbuei /vy 4b1/wrcard hands in order of increasing probability: (a) four aces and a king; (b) six of hearts, eight of diamonds, queen of clubs, three of hearts, jack of spades; (c) two jacks, two queens, and an ace; and (d) any hand having no two equal-value cards. 4/1dvwcur ebb9i/ ,my Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and drop thi8cj6cbsjr/yh .. w+ei(ee,sem on the floor. Construc b ( e6.isscjc+.eywji 8r,he/t a table showing the 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 prod3;.0v5 b/kf3jlbu hvgwmb-mt uce about 40 W of electricity per square meter of mb f l/3gbmb;-jw h0uv3.v 5tksurface area if directly facing the Sun. How large an area is required to supply the needs of a house that requires $22k\,Wh/day$ Would this fit on the roof of an average house? (Assume the Sun shines about $9h/day$)   $m^2$

  Energy may be stored for use during peak demand by pumping water to * . zzozljhj.+a high reservoir when demand is low and then releasing .h zzl*jz+o. jit 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 artificial lake created by a dam (Fig. 15z( a/r9 l1fwsm–27). The water depth 1r/ls mzwf(9a is 45 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 desidd+b ;ycdje n7b93 d b,7u;e 2gwl7lxcgned 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 + dgxb3bdccd2eb;de,y7 9;7w uj n 7llclaim? 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 gasolinvx5 d, grm:m1.47e0qoa rdc7 etojp(oe engine has an efficiency of 0.25 and delivers 220 J of work per cyc7m 0rvgco edx ,eda m1:p5rtjo4(q .7ole 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 enx/ xas3b(9ek1 3i gjubgine) absorbs heat from the freezer compartment at a temperature g9/3 b(xjue3ak 1sixbof -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 developed that made use of rvyqnufc,* 4* the temperature difference between water at the surface of the ocean and that several hundred meterq*n ,v*ryu cf4s 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 dirept0ulthmj 9/ 0ctions when they collide and are brought to rest. Estimate the change in entropy of the univer 9/j0uhttmlp0 se as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminui )we :u;yq6ny7xljs 4m cup 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 coef 26)wpb lwtgd(ficient of performance of an ideal heat pump that extracts heat from gb(6p) twdwl 26$^{\circ}\,C$ 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 rg.yuff xl ;mrh:.7/t in a car releases about $ 3.0\times10^{ 4}kcal/gal$ If a car averages $41km/gal$ when driving $90km/h$ which requires 25 hp, what is the efficiency of the engine under those conditions?    %

  A Carnot engine has a lower operating temperw)in44 o8si .eq 3rebn*ei2lmature $T_L\,=\,20^{\circ}\,C$ 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 to6nz 0+*hgpur+gr ue0y state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, +yur* 0 guph+z6 0rgneand (c) AC directly.

  A 33% efficient power plantfnn6 -lur; ( uv3qa7cm puts out 850 MW of electrical power. Cooling towers are used rfnl37- ;uc(6n qmva uto 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 deliverf1qbtjqf1we/-r bu tj4+ hj., s energy at 980 MW using steam turbines. The steam goes into the turbines supqbj -,f u1twrj/ qf1b .ej4th+erheated 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% efficiency. Assume the engine’s wat6btcj0*d d7 26nl6wj 4k muoloer temperatc* 260l dj6klbowomjud6 4n7ture 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 area1*zo ciee mo1 +xxvk,*o jj;5t $0.800m^2$ 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 inz m wjm g7qwdxp+ou4 /h;.s(*yy jo8k- about $ 3.7\times10^{7 }J$ of internal energy in the body.
(a) In one day, how much fat does the body burn to maintain the body temperature of a person staying in bed and metabolizing at an average rate of 95 W? $\approx$ =    $kg/d$(retain two decimal places)
(b) How long would it take to burn 1.0-kg of fat this way assuming there is no food intake?    d

  An ideal air conditioner keeps the temperature inside a roo+ -zpxdzxnx /+*j+ iduk.yoa3qiy80cm 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 open donukfo) 3-pm ab1n -n0yor.” 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 int mnnayko-b31pu0f- ) no 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