What happens to the internal energy of water vapor in the air that condenses 8 *ydl*jobun6 on the outside of a cold glass of water? Is work done or heaby 6*ojn*lud 8t exchanged? Explain.

Use the conservation of energy to explain why the temperature ofq k- dpbw,i62 +vfmh,,-pqq kw a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the tempekd +iv 26-w k,pfqmh ,q,wb-qprature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by +pz .2kcwv95 -ieryts2 cjxfo 69tnc1 an ideal gas. Is this enough information to tell how much heat has been added xw 9 csc+j6o21e 5r2yt9f -.vciktnpzto the system? If so, how much?

Is it possible for the temperature of avbvi0a9 i9 9ne system to remain constant even though heat flows iii9ven9v9 0 abnto or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is a77cy:bttyfh5 f9p-3do3c u zg diabatically compressedy7dyfb c3 cp5-9gf:3h7 ttuzo .

Can mechanical energy ever be transfo uncm v3sooz8.fv*7h1zl;b i*rmed completely into heat or internal energy? Can the reverse happen? In each case, if yoni mshf7ovz31 * cuvl;b *z.o8ur answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by p4*lxu ek87zfleaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator doorfz7lxkp *4u8e open? Explain.

Would a definition of heat engine ecai1gr.;/i - u ddx.zhfficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in (a) any6m*7tk/ 6hjc)vj l 4eydx br0 internal combustion engine, and (b) a steam jh7 6y*vxyl b0jd6/rc)tk4 meengine?

Which will give the greater improvement in the efficienmwpqc io9(*b b+g7h: ucy of a Carnot engine, a mq(7p*icu+gwbobh 9: 10 $C^{\circ}\,$ 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, inx qi .1c*obs-z general, is it not possible to p-qoc1zs.xi*b ut this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b)s n*dw4*ngz :u rf4i.a isothermally. In each process, does the entropy increase, decrease, or stay the same?sgiun *f.nw*4 zra4d: Explain.

A gas can expand to t9t,hkp1kv eo5ze-wf5wice its original volume either adiabatically or isothermally. Which process would o,v-h zw1p kkte5 9e5fresult in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of n- i ij/vi3:hdcrr(r4zaturally occurring processes in which order goes to disorder. Discuss the observability of thv3h:r jdir/4i-c(z ir e reverse process.

Which do you think has the greater entropc r x3;ynaghtrdp*5+7y, 1 kg of solid iron or 1 kg of liquid itdgr7+yc3x h a*5;p nrron? Why?

(a) What happens if you remove the lid of a botzj0:w klh0ll n)3t. tytle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples00j3)lh.w: z tykll nt of irreversibility?

You are asked to test a machfzu*/n au+ i0hine that the inventor calls an “in-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 cominfhz0ua nu/i*+ g out of it. How do you know that this machine cannot cool the room?

Think up several processes (otherfan,e.u2jx -c +q7bob than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violate the s bebq f u.a2cx7,-+njoecond law.

Suppose a lot of papers are strewn all over the floor; thlw2,qd- j df/hen you stack them neatly. Does this vio /jhd-,fq2wd llate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically state5dsydxm,6ppo s 24) cwd as, “You can’t get something for nothing,” and the second law as, “Youp)dpd2swx4 c y ,s5om6 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 tells us in which slpggh r6 nruey 789,l.wdtm lay);91direction natural processes occur. If a movie were run backward, name some processes lpm8hru) 1d.,;w96ye l args7gn9ylt that you might see that would tell you that time was “running backward.”

Living organisms, as they zo) . kwdwm*+vgrow, convert relatively simple food molecules into a complex structure. Is thv.o ) kwzd*wm+is a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performinlp6 s3 j, )eaaz6ep)clg $ 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 wixs4,hq w *nn0gth a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gswg *0nqnx4,has, 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 constanta: 37c:6k lim7cc bptb pressure until its volume is halved, and then it:cb7lb63:a icm7ptc k is allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas at z:akqaq:fk( mz, vl5 0atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the origin0zqz:5k ,ka mq (av:flal pressure is reached.

A 1.0-L volume of air initially atu ub.c5q8jetmh wdg.r )08+qb cnw)n: 4.5 atm of (absolute) pressure is allowed to expand isothermal0b5qch:nm) uq8g .edw tw jbc+nu.)r8 ly until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, and lastly is brought back to its original pressure by 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 bei3s rtlke8d;1png kept in a container with rigid walls. In the process, 265 kJ of heat left th 18erlp;stkd3e gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas is compressed adiabatically to half its vnumpxu,(j7x,wh .dzpx-1 i)jolume. In doing so, 1850 J of work is done on pj )(xx .7h,,m-1wzjiux pndu 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 from 40 i a)pxtu.*g-qzsqg560 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop ugq -g6t a* xsq5)i.zpuntil the temperature reaches its original value. Calculate
(a) the total work done by the gas in the process,   $J$
(b) the total heat flow into the gas.    $J$

  One and one-half moles of an ideal monatomic gas expand adiabatically, pe k3azqv ,+oaik 0/gdm4f1plwz p4t9d2 rformingkw0mfz449io,g+dda2tz3 1vl pqa p / k 7500 J of work in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step pro4tl21j ag;li1x iiuc 5;0skyt cess. Heat is allowed to flow out of an idealc lt;x1iut;k12li gji 054a sy gas at constant volume so that its pressure drops from 2.2 atm to 1.4 atm. Then the gas expands at constant pressure, from a volume of 6.8 L to 9.3 L, where the temperature reaches its original value. See Fig. 15–22. 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 k4)f5 g.h(;l de okfghu1zlk5–23 shows two possible states of a system containing 1.35 e z(ukl )f1dgkk55g;hoh. 4 lfmoles of a 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 f75ildi 7 4;n ysa7jxnvrom a to c along the curved path in Fig. 15–24, the work done by the ga ysa7l7 ni5;v74njidx s 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 shozl.xp .;n o bmex-l8l,wn in nl z.e8x.m-p,xlb o;l Fig. 15–24, 80 J 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 pe261 d vepjn6utjee1(orson of Example 15–8 transform if instead of working 11.0 h she took a noontime o6u2jnpj1v d6ete(1 ebreak and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleepsr5.a4rx t ff5z 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 hf5a 4r r5xz.tf, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less p vi6r5lft-(urua ) u ns*for54er day, using the time for light activity. How much weight (or mass) can this person e(luo i r*v)t 565faurf-nu rs4xpect 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 of heat while performing 32vvpo ( 99qwkm900 J of useful work. What is the efficiency of thismp9v9(o kwq9v engine?    %

  A heat engine does 9200 J of work per cycle while absorbinoc fdjm*k xyv m4(0q1.g 22.0 kcal of heat from a high-temperatm4 cq kv y0o1(j.mx*fdure reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine3v q1) rnakk5k nx3 4b8rjq7ecu8mol jo(.r5s whose operating temperatures aree3 k7v5uqksb)l8 58o 4j.njnxc k rrarm1(3o q 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat e/z ,c:bxg2hg -aba88v ms/vhengine 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 theoretical (C-.hlv6bqc38f 4u8 c/qz x6j7lgxxofwarnot) efficiency x 63oh6c/l7bjf.-lv8 cuqfx w8xq4zg between temperatures 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 ambie5j lr7u)8 odybpzdch5;j7 sz;;5i oqjnt 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 transfe7ou5)d ; ;bzojl;jz5hj 7pidq 8 yscr5rred 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 oygwl3r(* 3mydlbm21l f 440 kW while using 680 kcal of heat per second. If the temperature of the heat sourcdm2my w*1yrb3ll3 l g(e is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperacnh bn.4bjvjklsh7rc;tud 4. l3 )/p7 tures 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 di-xs n*yj6x e+kscharged per second, assuxnk-x *+eys6jming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source at 550s y6c p*)mbzime,:,h qn qu4(b$^{\circ}\,C$ 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 1okzco v4yi3z0m j;k 1v98xs hits 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 pairss2tw mtj1reo duf:gkt69- ,x6a45 jgh, the output of heat from one being the approximate h4 : sj6trdxtg6g ,2k -ej uh1mo95ftwaeat 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 o3lc m)v,v(+nuk8 nc1ppffw:cub5;m, 8pwmhp f a freezer 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 operates wit n wi)r9gnncv 6cn2 k-*7v hi+bs8v,-)nzqshgh a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator p fu/;)ta9 zeghas a coefficient of performance of 5.0. If the temperature in the kitchen outside the refrigerap)a;geu t /fz9tor 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*mfg-8 5gr7vz2 hsbnf 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 ,r.ij j7-6qwt(dt ,x jipj.lqat 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 ltu9de 58sa e-eb;(zkphn n 4.2xoia8were possible to run it bac. lb-dpe nh58uszeao4ae;9 8t nxki(2kward as a heat pump, what would be its coefficient of performance?   

  What is the change i / zx,tu..zazon entropy 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 eg9r9ctpr+,ios; t ;theated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in evfgo3cgx jie(g 5 /fe vb5ei5n9i,r57ntropy 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 init3 w h3poo:9/tchfqz)wh ;e7vnial 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 the ground an6m4 4 ln+fwoydd coming to rest. What is the total change in entropy of the rolnd4+ yomw64fck plus environment as a result of this collision?

  An aluminum rod condhh) cmp(z+g (mucts $7.50\,cal/s$ 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 39l p-czndn7 +cx.odl1h uq/b, 0$^{\circ}\,C$ 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 a66.altv b-v p6om1gg lt 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 4pjk,vff ds6rp hm4d) *r -;yyand 650 K produces 550 J of work per cycle for a heat inpu),;4-p6*ykr dh4vyr pdffsm jt 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 probabilitiesn* shj( /a0zqk, when 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 in order of increasing probability: nyy /ag6d9f; yqt8hu 1(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. Di6aq8ygfnyd y t;/uh91scuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake +d3oqn6 ktv4ig xy3qa z3e8z2 six coins in your hand and drop them on the floor. Construct a taek4a3 oq 3+ngt qi62zdzx3 8vyble 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 produ+lzz rpyi:pk d1i6)*jay8mx(ce about 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is required to supplyplad yx(y +r1i86i:pz)kmz j * 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 watesgyw 4 5k6a5*-o stpwkog m3u6r to a high reservoir when demand is low and then releasing it to drive turbines when needed. Supp3wtop5 kwsauo*4 -g 6m gks6y5ose 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 sl(, 97gqehz, -:gu2,foxf cc yssi8d a dam (Fig. 15–27). The water depth is 45 m at the dam, an,ci,9:esco zlu 8qsfh(gyg,- s2 x7 fdd 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 M9 8v g43zqkpfjW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.508q9vpzf34 jg k 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 p/8 y-cv,y) 7nw znr*5mpevkn0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles per secondycpez*vry v n, -m)w58nn/pk7,
(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) absorbfaxm) 5ot+dd) s heat from the freezer dfxm 5))doat +compartment at a temperature of -17$^{\circ}\,C$ and exhausts it into the room at 25$^{\circ}\,C$.
(a) How much work must be done by the refrigerator to change 0.50 kg of water at 25$^{\circ}\,C$ into ice at -17$^{\circ}\,C$    $ \times10^{4 }J$
(b) If the compressor output is 210 W, what minimum time is needed to accomplish this?    s

  It has been suggested that a heat engine could be developed that made use of the9(pd6zhd svl 0qaj kdm-a;+5z temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the tedzv6s add k +5(lh9 z;jma0q-pmperatures 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 oppositw7gtl m* 6a +ach3rm s8p96 di(wpgmq2e directions when they collide and are brought to rest. Ep wqct( 2 sh 9rd6*glmwa+6p7g mi83mastimate the change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cumvnz;.ig 4yd wl2. eo-p at 15$^{\circ}\,C$ is filled with 140 g of water at 50$^{\circ}\,C$. After a few minutes, equilibrium is reached.
(a) Determine the final temperature,    $^{\circ}\,C$
(b) estimate the total change in entropy.    $J/K$

  (a) What is the coefficient of pegx snru*/ 95wvk;btae3m -e8 yrformance of an ideal heat pump that extracts hea tmaeu3y*s/; 5kgx-8 ebnvr 9wt 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 releases a 8c7o *rww+e-tj:ilp3c og sd;bout $ 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 operatin4p -pnci.1ap+h oxxb 9g temperature $T_L\,=\,20^{\circ}\,C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal gas in going from statej2,g xyx 9e3ng A to state C in Fig. 15–28 for each of the following processee x,2n3 gyxgj9s: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical poz2.mzzqhl ,g :wer. Cooling towers are used to take away the eqzl2:, hm zgz.xhaust 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 planorjb5 q .fs)t*t delivers energy 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 turs)oj b*.q r5ftbine 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% efficie: ,*wnql+az cr;sl g0vncy. Assume the engine’s water temperature of +lg;*0, rv wac qsn:zl85$^{\circ}\,C$ 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-sec6pwdr80.eg .onq 1m( ;vlf bcr10rczztional 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 inlg5kw d/3 czhkvyu7y m8ayrrk/6z46* 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 keepz77:9 m0fk+ -ecisiktf o:eo qs the temperature 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 “rey (d+o;, 8b9mijtnfvffrigerator 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 bmf,8 jnvt(f;9iby+ doy 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