What happens to the internal energy of water vapor ih;s48ypdc v6b9e ihs,n the air that condenses on the outside of a cold glass of water? c, d89s; i46bhevy pshIs work done or heat exchanged? Explain.

Use the conservation of energy to explain why the temperature of a gas incref;t. l7sor1yox a6n (/ebx;hwases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperatur(6h ;xoe 1/7as oxyn;wlb .rfte decreases when the gas expands.

In an isothermal proces,hk i(s )scnwt pl0t/2s, 3700 J of work is done by an ideal gas. Is this enough information to tell how much heat has been added to the system? If so, how 0s )s2 wn,th(tpk /licmuch?

Is it possible for the temperature of a system to remain cont07acq3wt 5ai stant even though heat flows into or out of it? If so, giv3catqa0wt 5 i7e one or two examples.

Explain why the temp1 +v; s)szyqfkerature of a gas increases when it is adiabatically compressed vfk)q; +1sszy.

Can mechanical energy ever be transformed completely into hean.0 h,cb cpj4e43jyxvt or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yejcp4bh4v 0x.ce, j ny3s, give one or two examples.

Can you warm a kitchen in winter by leavihcf6fn md ; q o:)7ql,-hk3 d7fd0gdszng the oven door open? Can you cool the kitchen on:hnmlkzg)60 c-o7dd q ff3hs,q7 ; ddf a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of heat engine efficj; fxg7,vwk-,u ;c4h lfo4wzs iency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in (a) an bnl;x-td8ptsf40r x.ra+jh3 internal combustion enginep4 jf.tx+n ;d 3rrlxbt-s8h0a , and (b) a steam engine?

Which will give the greater improvement in the efficiency:zu -mmjr(pw b:e m/0g of a Carnot engine, a mb e:mrg/juzm0:(-pw10 $C^{\circ}\,$ 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) ener+x qnhv ve,2ggn;ji7caz) zd,;f5ss*gy. Why, in general, is it not possib*z)scn,7h +,j a g z;v5dvesixqgfn2;le to put this energy to useful work?

A gas is allowed to expand (a)9-5z+vy,x dbqb2 cbvg adiabatically and (b) isothermally. In each process, does the entropy increase, decrease, or stay the 52q -,c xzybvbgv+bd9same? Explain.

A gas can expand to twice its original volume either574;stvabl ks89 3w8g fah mql adiabatically or isothermally. Which process woulw8ks3 l;ma gsht84fq7val9b5 d result in a greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of na 0dzki;l.rp4u;ldw ,vturally occurring processes in which order d .ld l;z0w;k,vi4r pugoes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater ev0(b zs()s:hb ;uis vgntropy, 1 kg of solid iron or 1 kg of liquid iron?v(vs(hz:ssbgi0) bu ; Why?

(a) What happens if you remove the lid of a bottle containing chlorine gas? (b) chj4p;dhar0me fnu h+ 7 93;zp5eulr( Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples of ir43r lh zrueje59h7d0cap;+pmn h( u;freversibility?

You are asked to test a machine that the ii hq6i9 c2pu )0lfk(vwnventor calls an “in-room air conditioner”: a big box, standing in the middle of tkipif2vc9) 0uhlq6w( he 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 (oj sd0s s;x. 596neckzlther than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violate thn6;jlss. k s 9zc5xde0e second law.

Suppose a lot of papers are strewn all oc:e0rck+h 1uy n +pqkb .*au3uver the floor; then you stack them neatly. Does this violate the second law of thermodynamicn3y ue+*:au+ phkb0qcr. 1ucks? Explain.

The first law of thermodynamics is sometimes whimsically tsfe4b, calo.,cdm,q aw):/qsx az4: stated as, “You can’t get something for nothing,” and the seconda,zalfsw)oa ,:x 4:tdmsq/.,e4 cqbc 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 6f g6y/6fuktazmt2c 8it 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 tyt6fgtma /8 66cfkz2uime was “running backward.”

Living organisms, as they grow, convert relatively simple food molecules intoih7ye7vzm ypa5, h z,, a complex structure. Is this a violation of the second law of ,yh,ivzmp75 y,aezh7 thermodynamics?

  An ideal gas expands isothermally,0 /ridsjr: *qqavt;6 d 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 cylindfy( p i:lg9oz1d-akhfih 1cb( n.ox6:er fitted with a light frictionless piston and maintained at atmospheric p1l : anpif 1yz(ok i h9hb6.xf:cgo(-dressure. When 1400 kcal 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 of- ct7kdf-v6 -muf0guntil its volume is halved, and then it fcum 07-dt6- fg-k vfois allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the follow tw *5*9y7dqset cqxd*ing process: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, q*e td7 cs9y w*q*x5tdand 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) pressure2 )/,ffmg+.t:za lw swrvjwr8c 4upk2 is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initia4gmwv r. +wk t j8suw/lfp)cr22 f:za,l 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-;rfoqfsf8xs- 7 m5lh6s9ah j cut in half slowly, while being kept in a contain f-5; f qhmxsl7- r68h9sasofjer with rigid walls. In the process, 265 kJ of heat left the gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas is compressed adiabatically to half its volumh,7suk1a k r8y 4,.mn:g chtag2qd ll;e. In doing so, 1850 J of work is do;ynscat84:ka,u 2l,gr7g1l hdq .khm ne 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 from 400 m w)ljgr (n98shi 2k(g1*mevq pL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allo) ginj 8ehl(9kqvmgws 2(1* prwed 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 adiabatically, perforptm-7t8h 8d yc-0ionm ming 7500 J 8mmpi7hyn8tto0 -c -dof work in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat ; ;7lv wf+:lc bgpps)mis 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. Calcula;w blcpl gp:vsf);m7+te
(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 1logvmz4 jrh43n .z 8enrr75 j7wa,dy4.35 moles of a monatomic ideal7d .jo8 4lrngj3azyhwz544mer7 v,n r 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. 15–24, the )y n*7hh lkry46jqc9 rwork don)rnrhky*hcy9j7l6 q 4e 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 taking a gas from state a to state c along the curved pate, qki(.ocw0ydr 4ej6 h shown in Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on thwk 6dcj.4o,eqyi 0e(re 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 transr7;eggc- dn3 hform if instead of working 11.0 h she took a noontime break and g;n3c-dhg 7e rran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sitta37,s 5ms wnp)c c.zqs at a desk 8.0 h, engages in light actacwmssqtz, 7n3 5p).civity 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 vh8 c2np zp(m/1, qh6 *yfolla*rtrkko0 2qg+weight by sleeping 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, al,mrrkq/q2fpz* 2 +o(0lhotk 6yva c *pgh8n1 ssuming 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 3200 J of useful work vpy+a s:mi03z. What is the efficiency of this enz sap :ym3v0+igine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22. /m/gcz3 6ykz6hxiko10 kcal of heat from a high-temperature reservoir. What ish z6c/gk13mzxki y/6o the efficiency of this engine?    %

  What is the maximum efficiency of a heaign(uj , s5aw3eq3t7 k smv4o6t engine whose operating temperatures are s(e tu63j4k73as ,n5gvqw mio580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperaturem tu rz5xczeaq1+-rkt2 +/eq* of a heat engine is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operates at 75% of its maximum theoretical (Carnot(7u5 fj76q o;yyhjrfv ) efficiency between temperatures of 6jq ff7r56ohu;y7 y (jv25$^{\circ}\,C$ 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 / xi d1bh2yr68gtr v(cheat engine’s hot environment be hotter than ambient temperature. Liquid nitrogen (77 K) isbv6yh (2i /tcrgxrd18 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)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 4il(b4dei l b7z lo1* *q) )bib25tbsmt40 kW while using 680 kcal of heat per second. If tz qt1o*)ell*b2i )45 bdbbibi7t s(lmhe 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 4bj7te 0)f1)rlk th x.uhjak :3e3pga qkh4 h7are 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 5 m de(ox+hdv3zz*akjf(*j2g1 50 MW of electric power. Estimate the heat discharged per second, assedd kj21 g*3oz+hz*xfv j(ma( uming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes3 bw *yz9opg6t a heat source at 550$^{\circ}\,C$ and has an ideal (Carnot) efficiency of 28%. To increase the ideal efficiency to 35%, what must be the temperature of the heat source?    $^{\circ}\,C$

  A heat engine exhausts its hevp75usr0, q qlsy sc:)at 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 engino 6vhpak d/a0;es work in pairs, the output of heat from one being the approximate heat input of the second. The operating temperatures of the f;vao hd/ 6k0pairst are 670$^{\circ}\,C$ and 440$^{\circ}\,C$, and of the second 430$^{\circ}\,C$ and 290$^{\circ}\,C$. If the heat of combustion of coal is $ 2.8\times10^{7 }\,J/kg$ at what rate must coal be burned if the plant is to put out 1100 MW of power? Assume the efficiency of the engines is 60% of the ideal (Carnot) efficiency.    $kg/s$

  The low temperature of a freezer cooling coil iraaotxoo., 2-g:x7ea s -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates withgt; t:(j;dp*q fkxbol p3m 9/: -qz1vspchhc2 a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of perfor-y7xhr srp m/8mance of 5.0. If the temperature in they-m 8px 7hrr/s kitchen 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 b2 (i m dr9,:dmkuyeczn(1s3rkeep 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 05*w vvp;1 du4,pk5uud ov udi+$^{\circ}\,C$ 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,s0jzy3:-z c/ng uxv* s7cdn w it were possible to run it backward as a heat pump, what would be it g0-v cs:wu sd cnx/,n7yj3zz*s coefficient of performance?   

  What is the change in entropy of 250 g o6rr;xg1w0c c-sc c:lc f steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heated fromrwdm e)6muqkd n8zi/fz/+-9v 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy oi6w4zpx6;jyo 88*udz)r r x jnf $1\,m^3$ 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 initl9 lc k)4 +hlfchzv05g;ul 4xfial 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 kineti1ktqj xo3ptj/ ax9;*qg2ej8k c energy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment as ag tk2p19jk*q xo8 3e;xta jq/j result of this collision?

  An aluminum rod conduj/xnug)lqy ;u87ixl f /* i8kpcts $7.50\,cal/s$ 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 3q6mem d)b;+k0er uxf 64)ekzt0$^{\circ}\,C$ 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 aluminuab:)n9w iq0 rhm 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 prlzqlc o-l:nvj(y.ea;9h 8 o k3oduces 550 J of work per cycle for a heat input of 220(n.-9j qova l;3y cle:hzl8ok0 J.
(a) Compare the efficiency of this real engine to that of an ideal (Carnot) engine.    % of ideal(Round to the nearest integer)
(b) Calculate the total entropy change of the universe per cycle of the real engine.    $J/K$
(c) Calculate the total entropy change of the universe per cycle of a Carnot engine operating between the same two temperatures.   

  Calculate the probabilities, when you throw two dice, of obt3f3 uuyte98l gecd8 .ddoa,u2 aining
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following fivez:age;ccqh0xc7 (6 j nnd s6(r-card 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. Discuss your ran0 ((6 znq; :7jdag6ccenxsrh cking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and dgnm v (az*)f.lrop them on the flo a n*)g(m.vzlfor. Construct 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 produce about 406p8onxfa ys7+ W of electricity per square meter of surface area if directly facing the Sun. How largxp synf+ a76o8e 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 watednj6 mdrs *h3o mvy.8+).k qxq.th s+xr to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumped to a l3mkmtq. h.sosyx+q 8x)nrhdj6+.v *d ake 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 :4w: f/cy.nkkawl0 owwater depth is 45 m at the dam, and a steady flonol4 w0 /k w.akyfc:w:w 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 ,ghq+ywi) iwfv/9q2y -qa0jvakar;( engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.5jr v+hiaw9iq0aa) q-;ky2fq/y w,(v g0 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 a4c(rrm ypug2fqnul78;9b k :dn efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When the engine fires at 45 cycles per second,du4b 7mqf;k8 :gcr n2(yp9url
(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 (th9 7gigd evdirlp z16w6l2.m,oe reverse of a Carnot engine) absorbs heat from the freezer compartment at a9 r1 mpiol6 2,ezdgi 7dg6lwv. 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 t nz/fa-q -/kkqhat a heat engine could be developed that made use of the temperature a --q /knf/kzqdifference between 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 direcbu 2f ,fy/: 6vf1asc4um5pow/meqxe1c qxy 0;tions when they collide and are brought to rest. Estimafya,1qp:sumf/; y4 /ovm6c1 cq bue0fwx25xete the change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated alumiua0: 8hfvk5qynum 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 o3,md5eb y9tbficient of performance of an ideal heat pump that extracts heat f9yed ,bo b35tmrom 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 ov d. b 4;h98rngy*bdza 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 temperatui1xc0k t, 3b;m uo;gp tadur02re $T_L\,=\,20^{\circ}\,C$ 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 i ocd(a2z+tmw f76s.ean ideal gas in going from state A to state C in Fig. 15–28 for each of the following processes: (a) ADC( td.+i7 ezsfmcaw6o2, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Cooling towersa /isk5um/p9q*.38 g sez vmiw are used to take awayipizv/.8ask5e9m3q/w usm*g 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 delivez (fl ;uzvjna.0 84smhrs energy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused hea hvzls;nzjmu0. 4 a(f8t 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 aboljcwk +ltza)w:+hm6tc8)x2 f ut 15% efficiency. Assume the engine’s water temperaturek: +m8w +xjwh 6cltc a)t)2zfl 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 cr8a +1bb; gmxptoss-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 results imr/+ fwn-;hr dn 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 keep439n kem5uh )b(zttk ys 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 “refrigerator with an open door.” ydh.f: )3irjiw xlgn zt -9lgc*up/8(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 th3ni: w(l*yf8gdp.uxj-lt z9 c r)i/ghe 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