What happens to the internal energy of water vapor in the air that condensesy :j3,k.,a,ogwu dyb o on the outside of a cold glass of water? o .uoy,3, ,jg:byw adkIs work done or heat exchanged? Explain.

Use the conservation of energy to explain why the temperature of a ++k. )dd swt* q wqappho5wv42gas increases when it is quickly compressed — say, by ppqwd2s *a) wph4q k+dv.5 +otwushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is done k2ssfyf n9 s3fdslno5dnqt:72j)6 2eby an ideal gas. Is this enough information to tell how much hekn2 td)3sdl 9j7sn2fs5 n q:62foesyf at has been added to the system? If so, how much?

Is it possible for the 1 v1wn tpps-xkl(pc3onv5fk59)bv5qtemperature of a system to remain constant even though heat flows in915 bt5v( ksc)k5-3p 1nl vfovwppxnqto or out of it? If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiabatlu4nn0 mpnz0mted12mg, ((lv 0u aw ;jically compressedn,0uw1l ml 0 pd(u(2mnnmz; t0vg4jea.

Can mechanical energy ever be transformed completely into heat or ixif 3j2i,+8 wrkemt +snternal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one osf8iwk mj+ i,xr3e 2+tr two examples.

Can you warm a kitchen in w0f q0080v*x x hwpab n9zv5ghfinter by leaving the oven door open? Can you cool the kitchen on a honf0apf gq w*hx080 5x9zb0hv vt summer day by leaving the refrigerator door open? Explain.

Would a definition of heapbkt2 jm ;ao04t engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and lo9 fat0lepm(0daeh : r6w-temperature areas in (a) an internal combustion engi f9 0atelp (dm0h:e6rane, and (b) a steam engine?

Which will give the greater improvement in the efficiency of a Carn6ycwkn9b yl9q+uay l7(7 it1zot engine, a 107 69+uwl ( ylazty917nki bqyc $C^{\circ}\,$ 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) eb+2u:a x(w9;z3 uyve -qlgam6crvd / xnergy. Why, in general, is it not possible to w udc9r vuz2:xq/lygbev(3x6a +-;a mput this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) is6w j:wuaim a. zdaj-dm,xc2 -8othermally. In each process, does the entropy increase, decrease, ouc-zi,jxma-w 6am2w 8.addj :r stay the same? Explain.

A gas can expand to twice its original volume either ad11iv8mfdasoi+ (/ lwaav0o1eiabatically or isothermally. Which process would result in aev/l+i1mo0f(o 1 da8sa1w iav greater change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of natural8e 3ab;saq n-z/dl4ccly occurring processes in which order goes to ds l a n/-a3;bze8cqd4cisorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1ma2n8diiu+gno3zo9 2 h2q-ba kg of liquid i2-qzmbih83ni+do22 gnuao 9aron? Why?

(a) What happens if you remove the lid of a bottle containing chlorine gas? (b) gxnph-0 7x z(glg0z u(Does the reverse process ever hapzx7p0 lgh( (gxzn-gu0pen? Why or why not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-room air c* (yb3uzos qi*qjd3 y*6 lmy8zonditioner”: a big box, standing in the middle of the room, with a cable that plugs io *3 uzm jy*zyliqs68(3y*qbdnto 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 procyti;2qet. ib0 esses (other than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would violate the se;q bet0t2.yiicond law.

Suppose a lot of papers are strewn all over the floor; then you stack them neax8hads ) d)axi(u0+(s-kyufmtly. Does this violate the second luf( y)a )h da+mx8ds(x- k0isuaw of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stated as, “You iva6 99q knp:qfq)z2) xaye5ocan’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how these statements co peq:69qaak yo9x )q)z vf25inuld be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it tells us in j1z 2mghv-p e*which direction natural processes occur. If a movie were run backward, name some processes that you might see that would tell you that time was “running b*vpmj1-2z geh ackward.”

Living organisms, as they grow, convert relatively simple food:j4 kw8f hg*foy xw7gt we+ay4h +u35o molecules into a complex structure. Is this a violation of the second law+:jyw f tx835ufwek7whha+g44oo *gy of thermodynamics?

  An ideal gas expands isothermally, perform u w+jvz lj))meq0v;bjc3:ks :ing $ 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 jq ah)ty7y+k *cylinder fitted with a light frictionless piston and maintained at atmospheric pressure. When 1400 kkjtq )+*7yy ahcal 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 coole/ r,n6gwxq* r9 cymb+/pnpgc/d at constant pressure until its volume is halved, and then it is allowed to expand isothe *6c9qnw/+r/y bmxgrn c,p/gprmally 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 at3t)s*6cl 9hn oq(hbqw atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermallwn q (6lt3 9*sqbohhc)y 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 init.h:sn ck7cwf,rlwdbs94a -x3w lod.1m ;4 nlcially 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 pressure to its initial volume, and lastly is brought back to its original pressure by heating at constant volume. Draw the procesn4c :7k34;9acdd1 -hn.w w.o fscbml rlx,ws ls 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 nqvybgqidt3; da93i.z m2j9 2a container with rigid walls. In the process, 265 kianyq99 vdj qtidg3zm 3;.b2 2J 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 com )nl4v5k7ok8d hxa 0 x/4xdeswpressed adiabatically to half its volume. In doing so, 1850 J of w 4/o4 sxnvkexadw)lk57h 0dx8 ork is 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 gge 4g/*7 creqat a constant total pressure of 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 temperature reaches its original valugqg*e4g7ec r/ e. 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, perf3n5e aty9 7mozorming 7500 J of work in the process. What is the change in temperature of the gas durt nmoaez957 3ying this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to flow out of an i6 c e8wxb5 sn5k1pwho3deal 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 reaches3hk6spn c 5w 1be8w5xo its original value. See Fig. 15–22. Calculate
(a) the total work done by the gas in the process,    $J$
(b) the change in internal energy of the gas in the process,    $J$
(c) the total heat flow into or out of the gas.    $J$  ----待选择----intoout  the gas

  The PV diagram in Fig. 15–23 shows two pospzrjqbva9 * r:tu3+ yh z97po:sible states of a system containing 1.35 moles of a monatomic ideay 3pozj7q9vb+*u9 r:htzapr:l 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 cursvz jy ll xtm/p;24/l0ved path in Fig. 15–24, the work done by the gas is 0/2tx4 zl/l ;pjlmv ys$W\,=\,-35\,J$ 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 ffi1x:t o7 rf2,xm9g-i k *tzjstate a to state c along the curved path shown 1 fxm* i2,rfitgzt7f:xoj-k 9 in 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 pe/buv5r+ j rvsq68my;irson of Example 15–8 transform if instead of working 11.0 h she took a noontime break vyr85j;6 b v/s+ruq imand ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of zy olpc8t 3i,l3fq(b5 a person who sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.pl83c(,q3i tb z5lfyo5 h daily.    $W$

  A person decides to lose weight by sleeping one hour less per da7g3+pvm1d ss 9 fh-fizy, using the time for ligh vsm+ 1i9s-pdff73hg zt activity. How much weight (or mass) can this person expect to lose in 1 year, assuming no change in food intake? Assume that 1 kg of fat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausxqmq)0hq (vj7 h uz p:+h-zqw0ts 8200 J of heat while performing 3200 J of useful work. What is the efficie-0uzw:hq(7q q hx0+zp jmh)vqncy of this engine?    %

  A heat engine does 9200 J of work per cycle while abtwtpc1cw m kv0 -)455pvnlsl;sorbing 22.0 kcal of heat from a ;p nl0cw1p5c )5 t 4vlkmwsvt-high-temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temperafh *kcz9a/wf7 u91mew2 qg9fltures are 1 99 ka *hqu/efwlmgfw729czf580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat es,528 nc sra,moag6jgngine 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 (Car.afv06f4f owf not) efficiency between46. 0ffa ofwvf 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 rv/gg(cdyw - ,y.e xi3a heat engine’s hot environment be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would bc3ig / gyw(d-evxyr.,e 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 ofvbxf/29io -axifn0 d . 440 kW while using 680 kcal of heat per secox bfo2vd -9n.0aiifx/nd. 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 tempenv9gle rj )s-5bgv(o.ratures 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 planf8g4af mt,z6d t puts out 550 MW of electric power. Estimate the heat discharged per af8 t gz,46mdfsecond, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heais 92xq8qgx4 2ip2l uvt 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 he,k ob k/1 wbobnikd c,/a3yp9f+b;e9 vat 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, syhwko)ek 5 qcg(*0 th:team engines work in pairs, the output of heat from one being the approximate heat input of the seq *okthyw g:(ke5h)c0cond. 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 qj8hj (u( cql/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 with a in 7n+)mbywa d8f. rn x 0)ftbttz8qb0y.a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5. f w0w) 3oy ;p9bbbxw1ysgp0.s0. If the temperature in the kitchen oub 90wsgpyx1 w;fbo)p0y3b w .stside 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 keep a house warm a kc 3iv oh:d;h e2e*(jpdyc.v9t 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 .n (rmomu.z7 ihpna--$^{\circ}\,C$ 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 haq gc - ;tuw ;+e/7cfuuezdb91ss an efficiency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficient of performance?ebd c;qe/ +g cut7-zu19f ;usw   

  What is the change in entropy of 250 g b p jf8j0tk7q)of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heatedm -mf w7tqbo.8 from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in es zaogo1 9u)v6ntropy 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 is/o-j gh319jilt ep-c nitial 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 striking8 t+ w1 2ouihjzb*a)jj the ground and coming to rest. What is the total change in entropy of the rock plus environment as a result *buija1) wj h+2 tjoz8of this collision?

  An aluminum rod conductsr /jv-geg2 cx, $7.50\,cal/s$ 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 3,k6 cj f ec1z3spzd,j40$^{\circ}\,C$ 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 ary17p pknax, m1yshb5 (.1ohht 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 andzeli*18t m0bextzq ; . 650 K produces 550 J of work per eqzti t ;.blze m1x*08cycle 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,oa(:a *d +(opypkr i qs l585mmt08vigcl;gf 4 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 in03 ns,ikck:i z(-.3 gfcwm g,g r1 xtfcgca(o5 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 rankinms zk.3(ggwt3go:cg0x n5r ac1,c i(f- ck, ifg in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand and drop them on the fl0;pc8q qz (*to2wnagd oor. Construct a tablw0t(dapnzo2*;q q8 cge 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 40 W of ele1 ;q0eytc w6-p(i gbg7ejf/hfiwa +n*:k b-ymctricity per square meter of surface area if directly facing the Sun. How large an area is required to supply the needs of a hous g y fa/w;10htbeqfnec y-p*-j7bi(m 6w:kig+e that requires $22k\,Wh/day$ Would this fit on the roof of an average house? (Assume the Sun shines about $9h/day$)   $m^2$

  Energy may be stored for use during peak demand by pumping water to a r+e6rpbmq b()high reservoir when demand is low and then releasing it to drive turbines when needed. Suppose water is pumped to a lake 135 m above tm6b+)e br qr(phe 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 b /kq bd,qxa0l-y a dam (Fig. 15–27). The water depth is 45 m at the dam,- qqkab/0d xl, 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 bvk 3n*jf1x a3 jm2xnp+jn9b 6vuilt an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.50 MW of thermal enerfnm 3k p+* jx2vnvjja6n3bx9 1gy 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 0.25 and delivers 22w:zr4i .vjat ;ljf( ho8x v8ac r f2wjy30ag)/0 J of work per cyc 2:0z gjlvaai rf ;ow)4vayfc8 rj3tj/x(8h.w le per cylinder. When the engine fires at 45 cycles per second,
(a) what is the work done per second?    $ \times10^{4 }J/s$
(b) What is the total heat input per second from the fuel?    $ \times10^{5 }J/s$
(c) If the energy content of gasoline is 35 MJ per liter, how long does one liter last?    s

  A “Carnot” refrigerator (th(z1iuvg ,nt- me reverse of a Carnot engine) absorbs heat from the freezerzt- mgv 1n(,iu 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 suggestem 2v;bu (/iusd pky62hbrz*) ad that a heat engine could be developed that made use of the temperature difference betwevmbudup2*rh b(; siak2)/y6 zen 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 r7+zh3o t6 i-j udo2ny+j-xrb in opposite directions when they collide and are brought to rest. Estimate the chanxyjo 2r- ob6i +n7ht-+ zjdr3uge in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminumy2 .6 cw. ztezt+ftjt. 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 coeffiazp 4)dlkq1 (qcient of performance of an ideal heat pump that extracts hadz)p1ql q (4keat 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 abscaj mxit )j8a-x,.3kout $ 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 opg7 7tl4gk9mj oc6 m9zbc*lp. werating 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 cyoa1j xsy xf+u,f6 28by an ideal gas in going from state A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, andu182,fx +sc6ayyxjo f (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Coolinj weugihg5w:2;ss7 0h g towers are used to take away the exhaust heat h0hiuww ges2;75gjs:.
(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 ener u ximjxi4vhcx(7,74(gr,qs lgy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unusev gri xx( j,7u,4i7s(4cmlxqh d heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine.
(a) If the river flow rate is $37m^3/s$ estimate the average temperature increase of the river water immediately downstream from the power plant.    $C^{\circ} $
(b) What is the entropy increase per kilogram of the downstream river water in $J/kg \cdot\,K?$    $J/kg\cdot\,K$

  A 100-hp car engine operates at about 15% eff1mhsrry xk(ne i,u(ha5g5 f-.iciency. Assume the engine’s water temperatu51-h(,haxe n i(5 r.kfugmsyrre 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 cylin/s z7c.p17zhct iq*p xdrical jar 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 resui8r9 -razhadj3 ) sxzc+,f6 c(mu2kjvlts 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 ror-7 dueoqb/:s om 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 rrqc1kyd1 )e7an 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 1c)q1yrer d7ktemperature 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