What happens to the internal energy of water vapor in the air that g( qa n8q6ao+fbyu o 1i0ge5a.x2) biqcondenses on the outside of a cold glass of water? Is work done or heat exiq(foey 8+qg5axi a2 ab)10qu.b6g nochanged? Explain.

Use the conservation of energy to explain why the temperature of a gas incf xlt /- kbomp xuv;b*-p2qvh+1+lpb/reases wh12pkqm vlbf + lb/;x+/opuh*x-tvp-ben it is quickly compressed — say, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is don-(z k s(xxo8poe by an ideal gas. Is this enough information to tell how k(xo- xsp( 8ozmuch heat has been added to the system? If so, how much?

Is it possible for the temperature ofzksv:ll. kyvm e *z8:+ a system to remain constant even though heat flows into or out of it? If so, give one or two exa .zkme:*+ yvskzv 8:llmples.

Explain why the temperature of a gas increases wheh1,-a2f vhos wn it is adiabatically compresssh12f,-ahw vo ed.

Can mechanical energy ev w al;4cj zkryd2w8;-jer be transformed completely into heat or internal energy? Can the reverse happen? In each case, if your answer is no, explain why not; if yes, give one4d;j cy2j zw;-ra8kw l or two examples.

Can you warm a kitchen in winter by leaving the oven door open? Can you cool thuti8xjv8e (aaf8)5wo hun*8c e kitchen on a hot summer day by leaving the refrigerator door open?af)cu nw8vit x8(h 8 8*uo5jea Explain.

Would a definition of heat engine effi 44za8z k7q sqo33fcir rryp*w0 4x,mnciency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperatbq8j0wq 5 w hi*wy7h5mure and low-temperature areas in (a) an internal combustion engine, and (b) a steam engine?5 jwqbq0mwh7y85ih w *

Which will give the greater improvement in the efficiency o9*g:l wr5+. te a1id voaehgx4f a Carnot engine, a 104rt w9e:lhxev*a+ 5ioad 1.g 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, i w46xq ev0 8nhohz1h i+:tivgrya:e8wnf6-g: n general, is it not possible i1qtg z:6hi yvxwh 4o8ne:a0h6 n+gwv:f8-r eto put this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) iso 7jv)cpz1 4mr7pjh g;nthermally. In each process, do p;hnr 4gjcz)7vj7p m1es the entropy increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volu/va-m-qwj /xyme either adiabatically or isothermally. Which process would result in a greater change wj/a/vxm-qy-in entropy? Explain.

Give three examples, other than those mentiw4dfig(+tt kef3a uqb3 8zh.6 oned in this Chapter, of naturally occurring processes in which o+adtue(3if863 h4z.tkf gq wbrder goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg6amc0 ig af -5elkk1dg+dl7:bn3n j/ i of solid iron or 1 kg of liquid iro fnkd5ajlnm1i/i36e l+k70c ag- :dgbn? Why?

(a) What happens if you remove the lid of a bottle con+84h9 nh0o7lu0fvwuuapr 9rhtaining chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you think9o098rv h ur u nfwah40+7luhp of two other examples of irreversibility?

You are asked to test a machine that the inb.x s0c d;:v-5tqv;ilu2 rgmuventor calls an “in-room air conditioner”: a big-52s dmc;rxiuvl: .vutq;0 g b box, standing in the middle of the room, with a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air coming out of it. How do you know that this machine cannot cool the room?

Think up several processq tv m*(ovs)c1es (other than those already mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, would vmc 1vt )vq(*soiolate the second law.

Suppose a lot of papers are strewn all over the floor; tjc53qfc z/b ;jhen you stack them neatly. Does this violate the second law of thermodynamics? Expc/j b;jcf 3qz5lain.

The first law of thermodynamics is sometimes whimsically stat2 alsm,n1 v8dewowf -wbz hl;b2p3+9sf/9lv ked as, “You can’t get 2 w +2vleh1ldv9mbw;3f 8 sza,n o/sfkpw-l 9bsomething for nothing,” and the second 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” becausemqus-p7eq;+ixee e cm +2zks kn84i3 .zm50zu it tells us in which direction natural processes occur. If a movie were run backward, name somxi-s+m; ez45c qus.pu+qn2e em37 k e 0zizkm8e processes that you might see that would tell you that time was “running backward.”

Living organisms, as they su,j)e- 3+c ntmoh6bxgrow, convert relatively simple food molecules into a complex structure. Is this a violation of the second law of thermodynamics?3)nox-uh, t bmcj+ es6

  An ideal gas expands is;1d ba8l ,y mgfrt(2yhothermally, 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 and main,bm0o 5eorpe0z f;z:s wu5 q;dtained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume ;o;,f0q e pbuwodmz5z er:50sis 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 coo7klg: nrg wm(gl5r1p+l+ njuu+yny6/led at constant pressure until its volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the process on a PV di76kn5gw nyg ru /+u r ylg+mln+j:l(1pagram.

Sketch a PV diagram of the following process: 2.0 L of ideal gast:lz jg0 mrrkc-)o0,n at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until ttokmg ): -zn 0j,cl0rrhe original pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is allowe2601iesk.lf 3emvk tnwn8y-*j wu n9fd 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 flwm.e06wituey ns13*92n-fk8 nvkj pressure by heating at constant volume. Draw the process on a PV diagram, including numbers and labels for the axes.

  The pressure in an ideal gas is cut in half slowly, while b)kr9c.d t0jdz eing kept in a container with rigid t90djcdzr. )kwalls. 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 almosn02 l/o hu*nlst ideal gas is compressed adiabatically to half its volume. In doing ssun/h *20olnlo, 1850 J of work 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 at a constant total pressure of 3.0 atme mn8.29vmbcg 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 uc8vbe2 m. gn9mntil 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 qfo1jf- nl(1u of an ideal monatomic gas expand adiabatically, performing 7500 J of wfjl1-(u n 1ofqork in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following two-step process. Heat is allowed to flow o62p 6a)mnss/jz9ad 2:g(uyir qi(q cb ut of an ideal gas at constant volume so that its pressure drops from 2.2 atm to 1.4 atm. Then the gas exp/uc rnq i2ag(y 6i()sbzqas pd9j6:2mands 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. 15–23 shows two possible states of a system contaiguv6: /sfge 7ening 1.35 moles of a monatomic ideal ggs/fgev7 e6:u as.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(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 alot fuoz+)-do v5ng the curved path in Fig. 15–24, the work done by the +5 -d uoftvo)zgas 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 alef: (4c8h+)6dwn enz oo3qilf ong the curved path shown in Fig. 15–24, 80 J of heq(fzfhwo o :ence6n+8d4 l3i)at 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 person of Example 15–8 transform if insteax 3k76yrh y,a5l *21vy jv(b4psa joutd of working 11.0 h she took a noontimj rav3yxa5t(h ysk,4*pvbl6jy12u 7 oe break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person lze+i)xafj4dx ,u3mbcb. 1 c) who sleeps 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches televizx,calx )1 edb uc.i )b+4mj3fsion 2.0 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 tqb xs+ewx2320 v3y hwu1rn2 ythe time for light activity. How much weight (or mass) can this person expect to lose in 1 year, assuming no3nb2 +23qys0w21xutyh rvx ew 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 320h6mjs 5k+35 pnehq* qz0 J of useful work. Wha5+q s63 mhze*qnp hjk5t is the efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbi*2y yoco o+,4iej1g kdng 22.0 kcal of heat from a higkooed i1,gcyjy+ *42o h-temperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose oper.cm rk):o0uysating temperatures are 58.rs: 0 uymo)ck0$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heatk q7qx .dxc/* wy88,u/kvqhw t 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 theo41asw.e s1-q hfl(cs vretical (Carnot) efficiency between temperatushwscq(-avfe1s l14 . res 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 evzxko.n90 mbzq/a2 1ou;e-osngine’s hot environment be hotter than 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 nitrogen “fuel” (Fig. 151 - o2o.9eauokzm0z ;/qsn vxb–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW w te:1z5j d-fyx,d xg1qy m 4lrx30h(fghile using 680 kcal of heat per second. If the tem ( xdgf5dx m tj0 y-l3gy1re1z,4x:hfqperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperatures ).fkw,ekvgk h t4 95qrare 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/1sfjcq0sy :h . Estimate the heat discharged per s1:sq c/0 sfjhyecond, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat sourcezc*8km *ea(d uw;5h+gjkm o 7v 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 ija3)bfjs 7:k ets 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 engines,g kc+ pdr4. nmtj )4:ulqeh2e work in pairs, the output of heat from one being thek44n:em g dqhrljt )cp,. +eu2 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 freezer cooling coil is -1rt txek8:xr06 r7l;wr5$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer v 2zdlt,td0 6koperates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficiezv4*h3h t xf:(dr-jt ent of performance of 5.0. If the temperature in the kitchen out4j h:df- rvtehz3*(txside 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 sj+h+z.k/re3 wpisawk*b/w *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 vkm+j*.g6g m b0$^{\circ}\,C$ 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 adw+i :vws00e0b vy/fqn efficiency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficient of perfwwqv / s ed:00vi+by0formance?   

  What is the change incxl9 h cr4j 13)esvj c3succ*, entropy of 250 g of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of wate-jru(9 pp3lj: q (4u/f g4snyl1k oswmr is heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change inn-z+4he3n- c y1iode n 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 spesf3rhd11m dy+3tj6tbed 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 ener/c*jj bx6juw+4o ikd+hz 8w2jgy KE just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment as a result of this collisid wh826oj uij/jw+xb+ z4 *jkcon?

  An aluminum rod conductsp 1-q*u4dlvt hnz/w)drc u6.s $7.50\,cal/s$ 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 3xrp0jn(r )* ,yemxdlai2 7,zq0$^{\circ}\,C$ 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 alumi e0im:f8 qxhe5num 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 betwee9if 8hn3w 0zjx3t,eqmn heat reservoirs at 970 K and 650 K produces 550 J of work per cycle for a heat input of 220 w 3fiq,390jemhtnx 8z0 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 probabilitieajn yta9un*5 o. k25iiby 2bx6s, 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 orug: ,g+hga+ 6rciv9n uder 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.,+9+ g6v:rghu guacn i

  Suppose that you repeatedly shake six coins in your hand and drqf;co rkb7 e04p7i(stop them on the floor. Construct a table showing the number of microstates that correspond 4oste;f7bp7r c 0q(ik 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 f 56wiylc0l;n produce about 40 W of electricity per square meter of surface area if directly facing the Sun. How large an area is required to supply the needs of a housli l60y;nwc5f 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 tdd yoa 5 0 1pz tg6l,5ntlavc2h9mjxa-jc; 43jo a high reservoir when demand is low and then releasing it to drive turbines when needed0-zy5ltdjlm5na 1a dajv4;gt hx2 cpj,o369c. 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 wat7v5ri coz4( fh0avku 4er depth is 45 m at the0c vafzk5(o4v7 i4hur dam, and a steady flow rate of $35m^3/s$ is maintained through hydroelectric turbines installed near the base of the dam. How much electrical power can be produced?    $ \times10^{7 }W$

  An inventor claims to have desim,d ps3v t,/,r+epf*t+cvcxe gned and built an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 cef,++pvt 3,cm*pt/dr,e vxs 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 efficiency of 0.25 and delivel/--y *i o ; 3rmigfeg- l.jq-hinf-qvrs 220 J of work per cycle3 /;eoyn-hfqf mi.vgjlii*-r--qgl- 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 (the reverse of a Carnot engine) absorbs heat from 2pinngw2;a:mr y 9 rz7the freezer compartment;r yg n29azwpi :7r2mn at a temperature of -17$^{\circ}\,C$ and exhausts it into the room at 25$^{\circ}\,C$.
(a) How much work must be done by the refrigerator to change 0.50 kg of water at 25$^{\circ}\,C$ into ice at -17$^{\circ}\,C$    $ \times10^{4 }J$
(b) If the compressor output is 210 W, what minimum time is needed to accomplish this?    s

  It has been suggested that(pxdenaeb 2ea/+5.r upzh874n 2y owj a heat engine could be developed that made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropics, the temperatures 7pr8u xn2aphob/e 5en +.adj2z 4wye(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 collioo smw o-)2zr;5vc.hv de and are brought to rest. Estimate the change in ento25or oc) zv;wm-sv.hropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated alumi) 4mjio t5;dtk 8pich2y9xr7d num cup at 15$^{\circ}\,C$ is filled with 140 g of water at 50$^{\circ}\,C$. After a few minutes, equilibrium is reached.
(a) Determine the final temperature,    $^{\circ}\,C$
(b) estimate the total change in entropy.    $J/K$

  (a) What is the coefficient of performance of an ideal heatgbrxrmf h42 vr1+5n1j pump that extracts heat from 1m 25bnx frgj+rv1hr4 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 reeqs;,1j9 y5 vmdg-olwleases 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 operatizvd8. 7 wryf;hng 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 gas in going from state A to state C in Fig62 zb;lj rbky8wj43 (dkqn mntkt 6o8.. 15–28 for each of the following processes: (a) ADC, (b) ABC, ajykk(wbo 8 6m;2nbr l8 6t.j t4zn3dqknd (c) AC directly.

  A 33% efficient power plant puts out 850 MW of elec 88+ -ba5bkw(z ghis5f gom*yxtrical power. Cooling towers are used to take aw5xof s byw 58aghbz8kim-+g (*ay 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 emro6 :7c7ds1u+ap hx3h /jcs 1.xky xxnergy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbiney pd c rxs uhaxj/3xhs:7 .m1x+ck1o67 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% efrqcf0aah:uk 92 c/c **je;xezficiency. Assume the engine’s water tempere k:hz;c/ u fqr0c*ca*j2xea9 ature 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:epelj/cbyuj 9drx 7*(th1 . v3ly;pf tall cylindrical 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 results in ab5xakf)fz.vvt1g l+ 8t out $ 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 room at sfv o pj/tu/0mw) u/)x21$^{\circ}\,C$ 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 essentiallda l1wc xl mw/6m9(l,ly a “refrigerator with an open door.” The humid air is pulled in by a fan and guided to a cold coil, where the temperature is less than the dew point, and some of the air’s water condenses. After this water is extracted, the air is warmed back to its original temperature and sent into the room. In a well-designed dehumidifier, the heat is exchanged between the incoming and outgoing air. This way the heat that is removed by the refrigerator coil mostly comes from the condensati / ,m961 lwmlla(xldwcon 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