What happens to the internal eneuf:m p: pd8yq/a0t*ac rgy of water vapor in the air that condenses on the outside of a cold glass of water? Is t umaypf/8qp *0ac:d: work done or heat exchanged? Explain.

Use the conservation of energy to exphm9l0kv *a h8qlain why the temperature of a gas increases when it is quickly compressed — say, by pus m98k vhh0lqa*hing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process9-muxjcsu.n( y+.y ls , 3700 J of work is done by an ideal gas. Is this enough information to tell how much heat hasjy .n+uy (-.xc ss9mul been added to the system? If so, how much?

Is it possible for the temperature of a system to remain constant even though m82 ft rn lw.a5n dki;)jq9bl8heat flows into or out of it? If n2bi 9n8 d8;f).l j kqltrmwa5so, give one or two examples.

Explain why the temperaturebw/r-ewo7 n6.qrjmb( of a gas increases when it is adiabatically compressedjn/bbo q6w -r7e rmw(..

Can mechanical energy ever be transformed completely int7e;xbjl-chf 6 o heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why notxf-; ec 76hljb; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven door open? Can you8 nx)u; jsvi7d cool the kitchxu)s8 ;7jindven on a hot summer day by leaving the refrigerator door open? Explain.

Would a definition of heat engine efficiencyd(vh+66uj unk as $e=W/Q_L$ be useful? Explain.

What plays the role of 5bt;sw/lh h. d6x7w bwhigh-temperature and low-temperature areas in (a) an internal combustion engine,d 76wbb5l st w;.w/hxh and (b) a steam engine?

Which will give the greater improvement in the efficiency of a Carnotw f4vtd(.4rjdh7wh f5 engine, a 5ht(vd7d hff rw4. 4jw10 $C^{\circ}\,$ 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 c* vnd,j+ntomwq) wj*-/3clrgy. Why, in general, is it not p nnoj**jv/ w3m ,c r-qwtlc+d)ossible to put this energy to useful work?

A gas is allowed to expand (a) adiabatican6s0 ;mky/s b48ya*y dj o 0/7qfimrrnlly and (b) isothermally. In each process, does the entropy increase60 y4n/ symr0f;ds/qmka* joi b 78rny, decrease, or stay the same? Explain.

A gas can expand to twice its orp ) jfjsdez+))iginal volume either adiabatically or isothermally. Which process would result in a greater change in entropy? Expla sz)d)j)jpf+ein.

Give three examples, other than those menti9 w, meq3wu(zconed in this Chapter, of naturally occurring processes in which order goes to disorder. Discuss the obseuw9q, mwe3c (zrvability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 76t7(t3 oxcbwvri7jd kg of liquid iron? Why 6r7xvt(dtoc jwb7i37 ?

(a) What happens if you remove the li c2bcr v ;gt2ajbu.t)5l/4)jear2k hsd of a bottle containing chlorine gas? (b) Does the revers c2rb jv.kl5jr/)hcs2btg)ut ea ;a42e process ever happen? 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-d9t9mh2 lb+t (r bly:oroom air conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When ( mlrd+2 y:99bhlottbthe 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 those already mentioned) thau;n 2z,2ln-+akeu vzl5u+lc-gbw t.ct would obey the first law of thbve n,ul5uncz zullgkac+- t -2;+.w2ermodynamics, but, if they actually occurred, would violate the second law.

Suppose a lot of papers are strewn all over th ,pxlj4snh40ae floor; then you stack them neatly. Does this violate the second law of thermodynamics? Explain.,0jls4a h4nx p

The first law of thermodynamics is sometimes whimsically statj gxt7p4ba./b ed as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how these statements could be equivalent to the formal sta/j.g b4p7ba txtements.

Entropy is often called “time’s arrow” beca4sggk9 +b gy;ruse it 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 time was “running bgr9b4+g g yks;ackward.”

Living organisms, as they grow, convert relatively simple food molecules into .chzjj :al: 2na complex structure. Is this a violation of tjzna:.2l:h jc he second law of thermodynamics?

  An ideal gas expands isotherma8sj4iad s 4,vdlly, 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 a)u dexw(jy pthw-r25+ u6 bts7nd maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is observed to increase slp6uu) 2xy tb-7ds( jer+h t5wwowly 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 i6j q qk-oq7oe1ts volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the poqeq-o17qk j 6rocess on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gas at atmospheric x4,r*4 w2 e hsbqp4tcepressure are cooled at constant pressure to a4 4t4,rcep wb2qxse*h volume of 1.0 L, and 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 initia y63t*p3 fow1w )x/e:akqtmmalz/ 2exlly 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 in3)/t wy:lwxxoaae1p kt36*q f /ze2mmitial 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 isd id(*2f7-e 9qcgh s6lbzsmun,a 8bk7 cut in half slowly, while being kept in a container with rigid wall *2d 8 z76lb,desh9bigm7c kaq -nu(sfs. 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 ad/2vnq -nb,cyon ac,p (4p(fxki h*5 xviabatically to half its volume. In doing so, 1850 J of work is done on the gas. 4,x(ik,xn * hc-ap2ycov nq(n5p /fvb
(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 constay9s3kn/r;xc zpgc5u/ nt 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 allowedky9c5 3;r x p//zugcns 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, perforzy otlsf //0)rming 7500 J of work in the processlt/)ory /f0 zs. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowu;0)q *im(1eur jywxn ed 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 9i)qy ex(un0 jwm* u;1r.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. 15–23 shows two possible states owry+ l-*tx; 1j(ypcz(a*tg a zf a system containing 1.35 moles y a t(*w*cy+j 1-zztlprag(x;of a monatomic ideal gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to7m3*pf) ol)h4kqdioy c along the curved path in Fig. 15–24, the work done by the goy)l4mihpq*) f7 d3ko as 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 stlek5b3xl ::jv ate c along the curved path shown in Fig. 15–24, 80 J of heat leaves e5 bjl:k3vlx: 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 person ofu+e7u8a zol .pk(f6ah Example 15–8 transform if instead of working 11.0 h she took a n78lua+ f6a pz.k uheo(oontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sits at a desir o utea;;1*c fxps5,k 8.0 h, engages in light asrf ,1;iax ectpu 5*;octivity 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 sleeping onr 6v3qrix:8)xe d/)h-x8zg bna) jrnwe hour less per day, using the time fob6inr)):3 v qgz)jxwx8n /r8rxedh-a r 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 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. ; b;l+ w7fyhzjWhat is 7;lbw ;zf+hyj the efficiency of this engine?    %

  A heat engine does 9200 J of wor p c ui/ :w;rfe(xo(:0ywso1frk per cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. Whauop(;i:r sewr 01y/c: (x wfoft is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating tempera glylq*mx74l-n7 zum,z+otw)tures are 5*l,ztnglmly +o mwqxu) z74-780$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine is 230ci ;h,g x .g*2clca9ut$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operates at 75% of iv gl6xa984f8.csotmits maximum theoretical (Carnot) efficiency between temperatures of 6x6 v.m9f48sao g c8ilt25$^{\circ}\,C$ 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 4 p 3j(aja8 ,otb2q4tnswe+rzthan ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the efficiency of an engine that made use of heat transferred from air at room temperature (293 K) to the liquid 4wjnj r z2a+oqt4a,8bet(p3s nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 4zl)4a w* / d3f2mmgegv40 kW while using 680 kcal of heat per second. If the temperature offgaw*/ldmzev24) 3mg the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating ,+d,nv+)ydzne qdma ( 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 elecotwj ;vn5 (/pjtric power. Estimate the heat discharged per second, assu(wn;j 5pot/ jvming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat source ato-m;cgh3nch c3g-h /w 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 exhauskue9ovki,3tq2 . /w uz xps4g3,szxh0ts its heat at 350$^{\circ}\,C$ and has a Carnot efficiency of 39%. What exhaust temperature would enable it to achieve a Carnot efficiency of 49%?    $^{\circ}\,C$

  At a steam power plant, steam enginee nq(ekei lfci* 1w,-7s work in pairs, the output of heat from one being the ef7ekq i*il-(e1c n,w approximate 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 freezerd)iy bwx/iy0se (paeoe8 7* 4y 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-freka+;e//t /dxt v8ik 2ccil it)ezer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a q03owagdp3:-pyw: hthn +a0 icoefficient of performance of 5.0. If the temperature in the kitch:p3t-+ qaha3hiw0 p nywog:d0en 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 keil0sfe y r0jq1r:ak1y ;qu .(eep 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 0g9 m2,6f ta7nv(k9j i cu wnt*p;swzrhhbu*48 $^{\circ}\,C$ 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 runjuo9oixn. 0;j95 eokwfl7b vr o4)s-h it backward as a heat pump, what would be its coefficient of performancxej- h n 7ov; )jf49ioo9wb0l5uosr.ke?   

  What is the change in entropy of 250 g of steam(sbhi;or h 7,v at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is ,x7wy(mblmdo 6q5/+ s)rx2xeb,m gl cheated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in ,wggy;4g0y0ir6 frwrbe1- wlau2 h-xentropy 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 j ge4 ssyii-qt)n-:l .zp7nb3 an initial speed of $3.0m/s$ slides along a rough table and comes to rest. Estimate the total change in entropy of the universe. Assume all objects are at room temperature (293 K).   $J/K$

A falling rock has kinetic energy KE just before striking thmqdx 9 ,e2 btljtj+;fta)61v ke ground and coming to rest. What is the total change in entropy of the ro qd,j;f6mktt21bte) al9 xj+v ck plus environment as a result of this collision?

  An aluminum rod condu-qb ax nm18fyj.s;oehtgk,8 )mw x.r/cts $7.50\,cal/s$ 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 39 ++w .rt 1syeklsye0r0$^{\circ}\,C$ 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 at 0mc *:7mtd ke.ixqp.s30$^{\circ}\,C$ 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 y8 kuabtdz+ 0p*0 aa j)b n5)mlj-clzz5rp52nand 650 K produces 550 J of work per cycle for a heat input of 2200 J.z8a0tj-b nbn )5pcl+a2rzakd j*ylu z0p)5m5
(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 probabilitiemnu//szg u5 zd gj*,z.s, when you throw two dice, of obtaining
(a) two numbers totaling 5. The probability is 1/  
(b) two numbers totaling 11. The probability is 1/  

Rank the following five-card hands in 4(0qvl0k(x2biu q nyn: pt .k*y,vmngorder 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 ranking in terms of microstates and macrostates qypg(tuy k(.:b,mv2n n iv*0knql0x4.

  Suppose that you repeatedly shake six coins in yo i w8hghea 4.2mzhjy08ur hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is thgi0jeyw8.8zhm2ha 4 h e 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 electricity per square 6 ),u8c8rbjg lgmfj)umeter of surface area if directly facing the Sun. How large an area is required to supply the neeuc)g6mr gf ju8l8,jb)ds 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 jn9-ll;:u-mr othgpwvt9 :qvsg 4dj;5 o1(zidemand by pumping water to a high reservoir when demajt : hl-jq( l954mgpoo;9:iug1 v; zvwrts-dnnd 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 dam (Fig. 15–27). The 7lylf y8 8 ui94ff+;f2rgf zs,)bastswater depth is 45 m at the dam, and a steady flow rate ofi+ gsfl 2zb;8ffs9,fyuy84)fsra 7lt $35m^3/s$ 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 engiepq2n5d+r j,awopz1 y7)wi ;m ne 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 energy at 215 + w5;17 dy,inpe p2zqo)rjw maK. 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 o1ixr +6;s;fv13k yfe5bv kklpf 0.25 and delivers 220 J of work per cycle per cylinder. When the en ;6lb+v;krfy kx 3 spf5ve1ik1gine 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 revers 1vbz9 pntesuv).w0f3e of a Carnot engine) absorbs heat from the freezer compartment at a temperature of -1zf .p90btu e)vn s3wv17$^{\circ}\,C$ 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 tyuyj as1 b,1ljz.vq0(uab) p2hat a heat engine could be developed that made use of the temperature difference between water at the surface of the ocean 1l 1s,) vbjzauybyp(aqu. 2j0and 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 opposim;y f2jh/a .jbte directions when they collide and are brought to rest. Estimate the change in entropy of the universe as a result of thj ha/;mf2b yj.is collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cu 6 ika+s+j8jcij9(kn op 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 ilvrv nxj65.l.v 0 fptyct),.wdeal heat pump that extracts heat fr,v frcy.nvxt5 jtpl.0l6).w vom 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 relxco0 46mox1 wzeases 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 .z l vop.nc9+ha lower operating temperature $T_L\,=\,20^{\circ}\,C$ and an efficiency of 30%. By how many kelvins should the high operating temperature $T_H$ be increased to achieve an efficiency of 40%?    $K$

Calculate the work done by an ideal gwr05- rw 2fsgfas in going from state A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, and (c0rfgrs 5wf2 -w) AC directly.

  A 33% efficient power plant olryxo n f /k,q)v6,ohj5u32fv z2:lfka/p - pputs out 850 MW of electrical power. Cooling towers are used to take away the exhaust heat. h //lx3a)p2fvvr :z jo q,5n-p, f6oy2kouflk
(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 plant6 mvoc we/q0.ug3 i*od delivers energy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits iociw. q60vume/3o* dgts unused 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% efficiency. Assume the engi-,kaeb )m4auhy;8gjl 3zlx 9km ;sqe4ne’s water temphlu e 9;8le4)kg,sx- abm43 ;ykjmaz qerature 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-sect q r+(ted8klw,6et:uo/+j f; noh+ljbional 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 re.bqdf0d uj *7m, oydb2sults 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 temperature559ms.g)sx yx v,pfdy 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 tg-q44q4yh9 5x2qvx o.f dkiudoor.” 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 auo44qh qxx9i.fdy2 -kq5 t4g vir is warmed back to its original temperature and sent into the room. In a well-designed dehumidifier, the heat is exchanged between the incoming and outgoing air. This way the heat that is removed 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