What happens to the internal energy of water vapor i1s)6:go b46xqgb ku mrn the air that condenses on the outside of a cold glass of water? Is work done or heat exchanged? Explai1 6uks:r4g )x q6bgbomn.

Use the conservation of energy to expl7k kz3*9avx, m2t c2i oyud3kvain why the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decrea9 3z2 v7co2k kav,kxt*i3mudyses when the gas expands.

In an isothermal process, 3700 lcv7to/gy)1 , 3mflowJ of work is done by an ideal gas. Is this enough information to tell how much heat has been added to thefvolgo,t3 wm/) 7l1yc system? If so, how much?

Is it possible for the temperature of a system oc( apq,ck(6kto remain constant even though heat flows into or ou ((c kaqkp6o,ct of it? If so, give one or two examples.

Explain why the temperature of a gas increases 0scva. xw+4sy when it is adiabatically compressea. svycx +w4s0d.

Can mechanical energy ever be transformed completely into heat ogg/ +5pijc2 sw(*nzp lr internal energy? Can the reverse happ zc /pg2j+gp*lwnsi (5en? In each case, if your answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven door open? Can you cool thvaslo.:co;34 t .hibye kitchen on a hot summer day by leaving the refrigerator door open t.ab yl: v.ocosh4;3i? Explain.

Would a definition of heat engine efficiency as 7kfwtz hnq+t9z9e l mnj (ugw.z;v90,$e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas in (a) an in6:yg32 yu33f,gn 2nclx v dekbter:n2nlxbg2gd3, fuecv3 yk3 y6 nal combustion engine, and (b) a steam engine?

Which will give the gy grko6s )v) l;or9nc;reater improvement in the efficiency of a Carnot engine, a 10k)cr;n losy orv9)6;g $C^{\circ}\,$ 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, in gen5+e-lnn2csaki6 ybug (:a+o m7 ,jf kberal, is it not possible to put this ener u+absf7onb-:6n(a+ y,l emic2k j 5gkgy to useful work?

A gas is allowed to expand (a) adiabatically and (bdwg mgdxknw9--923l gv0 3udg) isothermally. In each process, does the entropy in9d --ungm w xd3302gwdvlkg9gcrease, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either ac7futqa81 41;2npkicj ocz g2h4 z1eldiabatically or isothermally. Which process would result in a greater chan c;f8ctzhu 441zn2ic lk7 qpjo211egage in entropy? Explain.

Give three examples, other than thosumk ;1fx lu82fd-z7dne mentioned in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the observability of the reverse procesmudzkf7f1 l8u2nx-; ds.

Which do you think has the greato tfx+s1m cl7:(j5gyw er entropy, 1 kg of solid iron or 1 kg of liquid y:1wfm g(lts7+j x5 ociron? Why?

(a) What happens if you remove the lid of a bppv * 40 ln77xoaf*mxdp2e9bo ottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think of two other examples of irreversibilo0x7l* e4p9a o v2p* bxfdnmp7ity?

You are asked to test a machine that the inventor calls an “in2xszz,v2klnl jv e1(2 -room air conditioner”: a big box, s,l2z jv22 e(1nvz xksltanding in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air coming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than lcy+ 4 ,xb3qw(fw 8*qvkjw+buthose already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would y, bk( q48wxc bl+qv3 wwjfu+*violate the second law.

Suppose a lot of papers are strewn all ove *vb5bdwjv7* 9yase q2r the floor; then you stack them neatly. Does this vaw 9vb qd5j7b*y2v*seiolate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stated as, 6llyta, fy0:))q xghd“You can’t get something for nothing,” and the second law as, “You can’l6gh0y:) xafdq)tyl , 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 direction h wt0e9 n(kru/ygbx32 bo*u;bnatural processes occur. If a movie were run backward, name some processes ;r92bugtbhkx0u b wo(ey*/3nthat you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convenes bwli,3 5t+e9(g hart relatively simple food molecules into a complex structure. Is this a violation of the si+ lge( h bs39e5t,anwecond law of thermodynamics?

  An ideal gas expands isothermally,xckbzy wf+:t5x8v gg /c0wf)4 performing $ 3.40\times10^{ 3}J$ of work in the process. Calculate
(a) the change in internal energy of the gas,
(b) the heat absorbed during this expansion.    $J$

  A gas is enclosed in a cylinder fitted with a light frictionless piston andwfr ;1mhm+cl8trfo:d +7ov 0uo0qbf1 maintained at atmospheric pressure. When 1400u0rlo r++ v: odo f1hb7fwqmc;01m8tf 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 until eyg +7ic).twsm:k 7 -,bvyjwgxwd0,mits volume is halved, and then it is allowed to expand isothermallyb.gvw+7je-w) tmyk mg c7,i0ysdw ,:x back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the follyj8p+7pu hz4g owing process: 2.0 L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to p jg8+ 74uyzph2.0 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 (a:nuz/w2 l ofl2bsolute) pressure is allowed to expand isothermally 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 or2ll:nwuo2/ zfiginal 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 slowldwa9u ;9;a;v g rwcni+y, while being kept in a container with rigid walls. In the process, 265 kJ of heat ler u;a9; wd+9aciv ;gwnft 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 it3 f2bew;4/ brtc2p rqtbi :yp+r1xsg0s volume. In doing so, 1850 J of work is done on t; e+0tbtwbcrb3g/ xr:q2yprsi p41 f 2he 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 fd:xq0ya d vt9s8-zm/ 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until the temper t-/qmfxv az:90 ydds8ature 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 mogsx-ypn/a b4 )natomic gas expand adiabatically, performing-g/s 4)xn ypab 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 process. Hcvs,bnn6en5n 00:qsg eat is allowed to flow out of an ideal gas at constant volume so that its pressure drops from 2.2 at6ns n:5 n0scgbqen,0vm 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. 15–2c9 bq0kc)2gt3jaz3e+0hm ;h-i wu.qwv lj kd,3 shows two possible states of a system containing 1.35 moles of a monatomic ideal gask,zcak 0h9q3-gb2mw t 3 ;.d celj+h)uvw0ijq.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(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 p:hc*x1 nual;c(p *xyto c along the curved path in Fig. 15–24, the work done by 1y php :xcc(**nxa;u lthe 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 w*byt,w9 jd2u 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 the sy *yj2 utwd9,wbstem.
(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 persoj 1hwy- m o7rg60)jbgan1yr;en of Example 15–8 transform if instead of working 11.0 h she took 7m)h;bg jn6j oy1ea01g-r wrya noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic r bs/ f :m.jbk yrxg4lf+t:uib 265kl*yate of a person who sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2*bfsj2kg.l :6+u5 ml bft k4iy/by: rx.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 per day, using thegm e e+xwtn49wc:8w2ps 8 tmw. 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 thatxc2tmne +pw. ge 48 s:twwm9w8 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. Wh h/n9ck 68kp)hcfu( jxg6+a-fo nvo3aat is the efficiency of this enf ac)jngu6+x h6ank9v(fo/3c - 8kpho gine?    %

  A heat engine does 9200 J of wor(tdy7 d9xw8qjzh lely0: nk 4tvs -b*)k per cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the effidy-t(w:4e80sn lzldhby)v tk9*jqx7 ciency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temxljzk(l. y.op77h ya4.lu r7wperatures are 587plrk.7hjy(all. ox.uwyz 470$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine i 9fkh+ 1 gdsqvzf+q+05df yd3is 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 maximru i.q-q z*k/z 2q imda3;n3yzj, 9iybum theoretical (Carnot) efficiency between tempqdyr-y 3jzi iu3*q92;na m/qk zi,b .zeratures 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 ambientr*k4dz-aesiw lj8ag pa41v2 0 temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the effa vj-*2l0 epa g1d4swa4zi8kriciency 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 work5d4v9btc lve - at the rate of 440 kW while using 680 kcal of heat pv5bced9 4v-tler second. If the temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatu5wv:k vx j,u9 1+aqb r)s1fpkpres 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 drd0o: yhq*+fheat discharged pef0*dq yd:hor+r second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source at 550qo5/znkiyw nel;-5 6i hz; -bj$^{\circ}\,C$ 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 kpr pn npo9)v0z*1zwx .eydhwb5e,tu3w9l:-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-gm(c4 blt-dj91 whas , steam engines work in pairs, the output of heat from one being the approximate heatt4hb- dscal1 w-9(mgj 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 coil is lwlcvkm263ij z3x 1 x32h.,mmfoa nt2-15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigeratora3 z mb1oxi7*k-freezer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of per1iqdbw ai;a- -formance of 5.0. If the temperature in the kitchen outs1i -da;ba -qwiide 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 +p s u64gq u+:e-og zka/ukb*jkeep 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 waterhi+;syn y/bdrzbk+iv w 79;m7 at 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 efj,:mqv cec/n+ficiency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficicnq:/ejc mv+, ent of performance?   

  What is the change in entropy of 250 g of steab ap2cy- ctjn)1g0x )ym at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water i+jggrl 3hrr3 m zrsc4,n4 r(a.1c,kcu, q-rovs heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change ino9 z3u dwhc9,uv-jt,l lfds 8lvva,53 entropy of $1\,m^3$ of water at 0$^{\circ}\,C$ when it is frozen to ice at 0$^{\circ}\,C$?   $ \times10^{6 }\, J/K $

  If $1.00\,m^3$ of water at 0$^{\circ}\,C$ is frozen and cooled to -10$^{\circ}\,C$ by being in contact with a great deal of ice at -10$^{\circ}\,C$ what would be the total change in entropy of the process?   $J/K$

  A 10.0-kg box having an initial rrynlsf/5l ;- j iy0icic02p +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 Klq b,g:5r, xn4cp4ec nmts(a 6E just before striking the ground and coming to rest. What is the total change in entropy onb( l,cpt 4 m,s cang:4e6q5rxf the rock plus environment as a result of this collision?

  An aluminum rod condlgvb q i*(1jrk7 bti z4piq;8)ucts $7.50\,cal/s$ 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 30wwua91h )u(9e3hi r vn$^{\circ}\,C$ 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 aluafq +i/o; bgsyucjnu. (( ey/5minum 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 6506qe;yw. o1h kbmm z(x0 K produces 550 J of q6xh. 0mo ;mw1zekby(work 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 thrd *(c;b zswinx1g *6arow 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 probab;c, c d u+lg7+cda+gbbility: (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 ranking in terms of microstatcab7lggc,udd; ++ c+bes and macrostates.

  Suppose that you repeatedly shake six coins in your hand and dr9(vlw 2x k3gs7cs gm)oop them on the floor. Construct a table showing the number of microstates that correspond tosv 9x 72()cgslkog3wm each macrostate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40:) dp5 -erzadu W of electricity per square meter of surface area if directly facing the Sun. How large aua-d r )5ped:zn 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 2uer1 r9:qy fk.q (trspeak demand by pumping water to a high reserverquy .r(2 :ftq9ks r1oir when demand is low and then releasing it 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 dam7n kr 4xig cu-o,g5.vb 3ktzs5 (Fig. 15–27). The water depth is 45 m at the dam, and kbkitgur,3-n 4 5 ov5zxcg7s.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 cf8iwkn t:-m -cl+)tihave designed and built an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermalf+ 8twc)m-- icnit lk: 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 engine has an efficiencfs8r8-yhf gv- 93ej cty of 0.25 and delivers 220 J of work per cycle per cylinder. When the enginjych 8-ffg9s r3-tve8e 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 b,sow :to2qe)d1-kag 5fk .xeCarnot engine) absorbs heat from the freezer compartment at a temperatox osw)tqg,.b- edkkf:ea1 25ure 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 ez a5 oab8b 2w won;arl.0w0rl*1xg76x. rvew hngine could be developed that made use of the temperature difference between water at the surface of the ocean and that several hundred mlv086 2aob;rgw*anwxo. .ww1l 57ar r0 z hbexeters 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 collrob3y .k qbj e8fan49k-ar+m9ide and are b ym+3ro9fbekak.- q94 ja8n rbrought 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 aluminum cup at db8;cb00 o n)p5 n5dy;wuy mak.2ee wa15$^{\circ}\,C$ 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 heat pump that extract1-wfc dxol;b 8 rij*2ns heat-;1x* fobrclijwd2n 8 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 caod.4jx7 q6t tlloiu ),r 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 tem kfi: ao3fn5-f5 t7semperature $T_L\,=\,20^{\circ}\,C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal gas in going from state A to state C inj 0q cj 3cvyckp 74+u,/iezobil):-wa Fig. 15–28 for each of the following processes: (a) ADC, (b) il03ijcc) /pu 4qcajz-b +o7e:,y kvw ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Cooling tjmc1au1abqo1 ij0ay, 8h: 5fbowers are a,i b 1hjcf aa:o0181uj 5mqybused to 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 delivers energy at 980 MW using steam turbines. :prxk, ne ftmx. *kuis -c:x;7 az4cb/The steam goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbin : 4/: xrpx;btunf 7.eskzi-ckxm*ac, e 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 operzlkk ayl;. ple06(voj*p 7i k5ates at about 15% efficiency. Assume the engine’s water temperaturk*5v i lzpjleo a067k(. ;ykple 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-section./n+r 1.nxky;g a ixzfal 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 resul*rtr01rg 0 6 wb)nvzjmts 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 inside a ro vky/2u 3ngw e28*rvhfom 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.” The humid airou* ay3f/okxn+0p:bm 5 5zinc 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 k ni+ z 53 oobya0n5f*/ux:cpmwarmed back to its original temperature and sent into the room. In a well-designed dehumidifier, the heat is exchanged between the incoming and outgoing air. This way the heat that is removed by the refrigerator coil mostly comes from the condensation of water vapor to liquid. Estimate how much water is removed in 1.0 h by an ideal dehumidifier, if the 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