What happens to the internal energy of water vapor i/*m xyojqq3s(uw u z, c4t./cyn the air that condenses on the outsic// um c (x*wzjq3to,yqs4.uyde of a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to xtf;sg 77zug.explain why the temperature of a gas increases when it is quickly compressed — say, by pushing down onzuf.gt;g x7 7s a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is q7iow.m88w 4n5zubv tdone by an ideal gas. Is this enough information to te zu 5 tqb.nwovi748wm8ll how 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 thz;uz, ooee ef j)p 86r5p-zwt.ough heat flep zzr j)8zfo,e -teo;6 pw5u.ows into or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiabatically comprt 5vp:o4teqxt:d/ . )5dhzjrc esse5o/dh5xp:ttd4rz e.)vt:c qj d.

Can mechanical energy ever be tg9x*2 ltr 3ruzransformed completely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one or two examplesg9rz 2lrx *u3t.

Can you warm a kitchen in winter by lkvjkc(-; ml-,/(dj an1hfive eaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the ref/,k;hvv- nfmke c- 1jd((ij alrigerator door open? Explain.

Would a definition of heat engine efficiency ele9):*pmlm/ er0qtu gu3hi 9as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in (a) an icy1 s-qvu/ *thnternal combustion engine, and (b) a steam e-q /u hc*syvt1ngine?

Which will give the gr*efh eg7gy,/ 2lifo c;9 dewb,eater improvement in the efficiency of a Carnot engine, a 10 gl f,eo*;9ihdcbe,w2e fg7y/ $C^{\circ}\,$ 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 (internalss y;)34i bgfj) energy. Why, in general, is it noyg;sbisj )f34t possible to put this energy to useful work?

A gas is allowed to edfgfhwqo22 : 4xpand (a) adiabatically and (b) isothermally. In each process, does the entrop 4w:o2qfdf 2hgy increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either adiabaticallyn dhc, mjc*xk h*/5xvaz /*j7v or isothermally. Which process would resultxahj */v7hdx5, *c/*jk cn vzm in a greater change in entropy? Explain.

Give three examples, other than thosoj ctdskk vz(hvs 05 3 ig9r;8jx3+:rbe mentioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the observability of the j (osr kg3xkbz3itsj;: dvv508c+9 hrreverse process.

Which do you think has the greater entropy0zt /kd bm g)z* ;uq(fac7p/pm, 1 kg of solid iron or 1 kg of liquid irom fa;qzu k(pt/m)b/7* c0dzpgn? Why?

(a) What happens if you remove the lid of a bg b52p: bv:j6v;qw;aajcua04m+gwvlottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why no p:q5wuv2jg 6al:+gjavwac; 4m vb 0b;t? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine q ytt66hrky +c: 1foc;that the inventor calls an “in-room air conditioner”: a bi 1rhyft;+t6cy:kq oc6g 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 processesyvgc.7 e ,otx6 (other than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violat. g tycx,6voe7e the second law.

Suppose a lot of papers xpn6m wu4c4kl1v y12 cte,3zxare strewn all over the floor; then you stack them neatly. Does this violate the second law of thermodynamics? Explainz ,c3xl4 kp1v62ncym1tu xwe4.

The first law of thermo6ol bf;l+ -z; yfgvn ld9xj5;idynamics is sometimes whimsically stated as, “You can’t get something for nothing,” and the second law as, “You can’tx59;ov6ldlbff-+lz ; g nyj;i even break even.” Explain how these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because im olzu4 ew*w2/p -3cgvt tells us in which direction natural processes occur. Iflw- 3mv g*z2weu pco/4 a movie were run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they8cbuw 7/aqn z48 6gdeo grow, convert relatively simple food molecules into a complex structure. Is w 74du6oc8zn8b a/q gethis a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, pnagn9y5 q4a ina-cr 06erforming $ 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 friq0ck jvqhnq 48 (fur28ki. 8cuctionless piston and maintained at atmospheric pressure. When 1400 kca8kiju r8knqv 84qh0 2cqc (.ful of heat is added 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 pressure until i3umo *4 ki9knt);9vcu hvtfg9 ts volume is halved, and thhg9 utm*itvu9v4 ncfo; )9kk3en it 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 dkgzsbvi7/:w ee)*t4+ty uh )ideal gas at atmospheric 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 increhwg7bz ut )e+d /*4vesk:tyi)ased at constant volume until the original pressure is reached.

A 1.0-L volume of air aepuma8wkm n+i fs57j25qv2h k **3 kiinitially at 4.5 atm of (absolute) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant +8 n5kfs w7*2m *ek iua2hv5i3qpjmka pressure to its initial volume, and lastly is brought back to its original pressure by heating at constant volume. Draw the process on a PV diagram, including numbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while being kept in a con(n (*5qss rtlltainer with rigid walls. In the process, 265 kJ of heat left tss * nl(lt5r(qhe 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 nch1/j *;b keqnruw9-is compressed adiabatically to half its volume. In doing so, 1850 J of work ic9j nqe*rwn-b 1u;h k/s 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 3p jtmy,bbymj1 b,3 2(h.0 atm from 400 mL to 660 mL. Heat then 3y1btjmj 2,phb ,y(bmflows 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 adiabatb o 5m w0l a.apzz(mb*pq;*(heically, performing 7500 J of work in the process. What is the change in temperature of the gas elpa zpq ab5 m o(*m;z(w0.h*bduring this expansion?   $ K$

  Consider the following tjbu /.i3vqx3 iwo-step process. Heat is allowed 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 value. See Fig. 15–22. Calcui/.iq3bv 3jxu late
(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 containing 1.3;. ao )-xgm bwwvn.ei35 moles of a monatomi3x wmen;.-)g vo.a bwic 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 cur4i )-n-okzu javed path in Fig. 15–24, the work done by thea j4- i)u-knzo 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 to0 p2jdw+9 eytmbeuip6 3 jr g*w5uuf15 state c along the curved path shown in Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on thw5umd3j9ub*6te2 ig1r peup f 0ywj+5e 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 transform if instead of work7* l,5,ml dsjvffxud7w tog 3; ,m21wxhsx xs,ing 11.0 h she took a noontime break a hm,utjsowd2wx xxm x, s 77,5dg1sff,*3; vllnd ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person whoe 1hdm6e h d7lxnmi9k:5* a1 ph.or(aw sleeps 8.0 h, sits at a desk 8.0 h, engages in light acr nw*519l e:p6adxk.me7ho 1 ah(mihd tivity 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 sleeping2pww l23g -m 3y3)0 wnw7b)uzkwfvj d.dysh3 w 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 that 1 kg of hkwl3wyp2bs. vdw02u)3jn)3 7 w dfwm 3 zyg-wfat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while a: +wv2ie)cj kperforming 3200 J of useful work. What is the efficiency of this engi:vwji+eak)c2 ne?    %

  A heat engine does 9200 J of work per cycbjv:qgy98 n6 qle while absorbing 22.0 kcal of heat from a high-te9yq68nj qgv: bmperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency s (wq5.uoe )chof a heat engine whose operating temperatures areu(o 5)h.sw ceq 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature j yo 6h7moa3n.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 maximum6 p/kp:r:q imjgm2(kg theoretical (Carnot) efficiency between (gp:: /igkpjkmqrm26 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 ambientd,e8 7pu ;dmhduz .cm. temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the efficiencym8c mupu .z7h.d;de,d 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 0.:e(:oij luy9cmw. om zja 4qof 440 kW while using 680 kcal of heat per second. If the tempw.z .ojaj(: m9c qemoy:ilu04erature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operat745g yrjsveg 8ing 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 thei9mfun9/. q ow heat discharged per second, assumin q f9.onm9iw/ug that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source a or-; d6(3gbclg8qiibt 550$^{\circ}\,C$ and has an ideal (Carnot) efficiency of 28%. To increase the ideal efficiency to 35%, what must be the temperature of the heat source?    $^{\circ}\,C$

  A heat engine exhausts its heat at k0 g e+dn:zkp;pcdo(1350$^{\circ}\,C$ 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 enginesehi-) ,*l .u j.zafxyu work in pairs, the output of heat from one being the approxil *uxhe)uz. i-f, y.jamate 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 fre0oq5zvkht 9ln x9k(9e rmz ,i3ezer 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 operat) ,7//v up/tb0 wsihzji c)eftes with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of perfvdkat8ars w.af -v8 54ormance of 5.0. If the temperature in the kitchet-v a4f.wk8sv8 5ada rn 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 k70p .n(bq (b)qsur yrieep 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 0*ch 2q31 yobub$^{\circ}\,C$ 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 itk m;8irxjh1si5k yz515xe )pn backwarxjsn zik15;mei r )8hk51p5xyd as a heat pump, what would be its coefficient of performance?   

  What is the change in entropy3c74v adzrj7t 7wgsf7 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 heat m;)*dfygo yj w.yflr; )dy92aed from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entro 1zl6ea4/lrqtyav saio:9))iv/ :j lfpy 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 initialq z7moq5v84b )htu+aeg ,l8tn 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 bc jzaujvg f384ee8rw // (sr:jefore striking the ground and coming to rest. What is the total change in entropy of the rock plus environment 4 /ev8ruaj:w/g8c3(sjr fjez as a result of this collision?

  An aluminum rod condun2qmbellzt.pie5s) e)0gm( 9cts $7.50\,cal/s$ 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 305(4 lwubiqz(n$^{\circ}\,C$ 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 ,8emq7fnw (+e;: q)-g,o+u kxd r z8curbucytat 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 c xq-d3o5 v:u-rfaej1between heat reservoirs at 970 K and 650 K produces 550 J of workj ar:35uec-ovfqd -1x per cycle 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 tthb*1d7(r3bb/i;gf 1od ox ysd +bq(dwo 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 incr 5q 1p5u/guton8x xpn4easing 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 enpuo pxqx 4n51 u5tg8/qual-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your h1 iof c4i3)bf/q t4h5fr+bgxmand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probability of obtain4f4fxmq bb)i h5+1coi/t3rfging
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can proj2 cpyza1y84bm 1 i4hjduce about 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is required to supply the needs of a house thcy28bm h1a 44pyzj i1jat 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 dem0sbecg eq r,8-and by pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumped to a cger08s,-eq blake 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. 15–27). The watehg nc6d )d/l0sr dcshd6 d0)/ng lepth 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 designed and built an a(,k;y3oj-rylnc0 pnbsy p * +kn n;f2engine that produces 1.50 MW of usable work while takio +ns3jna 0 n;( pfypnkky,2-cbl*ry;ng 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 nyx/ s8v *(jxb5x8dwr engine has an efficiency of 0.25 and delivers 220 J of work per cycle per jxv/8s w* x(byxrn8d 5cylinder. 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 Carnftdt hp( k5 qxsl*kk+8ja j/vu, 2ta+.ot engine) absorbs heat from the freezexa/2(d*8sjkvp,+f l+th 5t.atk kju qr 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 t f0tg3syywf9m/.7kic hat made use of the temperature difference bes 9cgfytwy7i 0fk/.3 mtween water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars are traveling in opposite directions when they c3i (baz+yonlel,(m /uollide and are brough(zimb ,+un(y aleo/l3t to rest. Estimate the change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated alv34r.,-fj x5 /o y 5 exjnlhkfdu2u6upuminum 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 coefficient of performance of an ideal:bw*4b,h uubsj1)x- / rdqy ut heat pump that extracts heat frb-u4 wjqdx s yt :)bbh1r,/uu*om 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 rel y1. mk3lqxhsv1g;qr3eases 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 opn3glrvfvfeahz2w2/)s s- z ,36qo b/berating 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 7mc z;vhidknd3g*(:bby an ideal gas in going from state A to state C in Fig. 15–28 for each of :dc;zmhnk v*g 3(di7 bthe following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 3 :,c+qg bh5k ;jpxz/fnnj-ki 850 MW of electrical power. Cooling towers are used to take away the ex;n x q/jpkg-cnfzib:+,kh3j5 haust 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 MWbn;;aygwlhiws9;sq4tb14q5k l s; plj40gd6 using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbine operay9lnsd; 4 swpt1qkbh j05b4g64;gi;lswl; qa tes 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 ppf k7tmeb d e2yv);2r/jp7hf0 /aa9 t15% efficiency. Assume the engine’s water temperatur)rbepjtp/; p9 ad/v72f e7k 2fyt mh0ae 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 +ozl. y:eu ) *rscmgb;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 resultxi.ct/b p lo58r++wwbyx6qmzw1 k 1l,s 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 temperature ins*);yv8u 9gpda6tox icbw7g 1 nide 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 “refrigeratoruwls1ljrka:ysz q044z1-* p u 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 u* zs0k44jyp:qu1-wallzsr1 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