What happens to the internal energy of water vapor in the air 4 :xk6cm*e fy9lukj 2fwc4:vl1gkfd /that condenses on the outside of a cold glass of water? Is work do:4kcwlfef k 6 dx:m/c2u k941*jg yfvlne or heat exchanged? Explain.

Use the conservation of energy to explaija7c 2p ep t(ce3+-8iy afg:enk n9mg+n why the temperature of a gas increases when it is quickly co:agy8 if9ap-m +nk+npeje(gt2 7c3ec mpressed — say, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of work is done by an ideal gas. Is this enou+ gr)cnud+t608rbfgq wg;ig6gh information t+gng rtw0dq gc+) 6gr;8 f6ubio tell how much heat has been added to the system? If so, how much?

Is it possible for the temperature of a system to remain cpq*f 8g (kz0gtonstant even though heat flows into or out of it? If so, give q(gt kp*fz08g one or two examples.

Explain why the tempera/twf1 j t8red,ture of a gas increases when it is adiabatically compressed8fjwe r /ttd,1.

Can mechanical energy ever be transformed completely into heat or internalj zofr zoim .2rro0qz 4f:636o energy? Can the reverse happen? In each case, if your answer is no, explain why not;jooi4 :m.6rzo 2fqrr 6 z3o0zf if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven door opxe8ckg52bq j3 en? Can you cool the kitchen on a hot summer daybqkx g2e38c5j by leaving the refrigerator door open? Explain.

Would a definition of heat engine effi9 j+2n ry*lrd1fn1df c j;z4fs2ylde* ciency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperatu 0frn*ymnocr5zrn53l5srt+ :re areas in (a) an internal combustion engine,5ns r5rtnr3 0 *oy rc+nl:zmf5 and (b) a steam engine?

Which will give the greater improvement in the efficiency of a Carno5a m 89ewejf3gx/ d2ibt engine, a 5ew2/gf m39a jbd xi8e10 $C^{\circ}\,$ 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 thekw--rw4 mjm (zrmal (internal) energy. Why, in general, is it not mwkzm( -wrj -4possible to put this energy to useful work?

A gas is allowed to expand (a) adiabatically and (b) isothermally.tqooch2 6 jxt ts)o( *v0;yyl( In each process, does the e(x)ot 2*c0shtqo6oy(vt;lj yntropy increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volume eithe a8- a aflw:w0vz2 a;feb.j4ier adiabatically or isothermally. Which process would result in a greater change in entropy? ;lvz84 : a abwjfai.-f e0eaw2Explain.

Give three examples, other than those mentio ruzrbpn3/ yy cy-w:a w0.iftg/ 2ku0 o1:j;irned in this Chapter, of naturally occurring processeso: 1/j0 i-c0ybu3a;fywrry2 r g: /ti p.nkzwu in which order goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 kg of liquid x*,asgglr, 0h iron?s,g, x a*0rhgl Why?

(a) What happens if you remove the lid of a bottle co. 1km7rnb.jtvx4/ inpntaining chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Cxkrt.mp4.bnvi 17 j n/an you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-room air cjp0g8nd :,y,1uxag5eemo 6 y m-tfr( ronditioner”: a big box, sn rt 6pmrm,g(0o ,e -a5xdejg1yyuf:8tanding 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 t -ey5ioz esy18han those already mentioned) that would obey the first law of thermodynamics, but, if they actsyoe8iz- e51 yually occurred, would violate the second law.

Suppose a lot of papeyjox24rw:,4 d luy1kdrs are strewn all over the floor; then you stack them neatly. Does this violate the second law of thermodynami4xd: yu 1l2rojyw,dk4cs? Explain.

The first law of thermodynamics is sometimes whimsi q:( 5zi5owds k35hy urcqv2m/cally stated as, “You can’t get something for nothing,” and the second law as, “You can’t ovhqyu :( mi2 w5kc3dz/q55rseven 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 whichg) f,azrrl6j gr;au59 direction natural processes occur. If a movie werlzr;g6j r9uf ,5)agare run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively simp4e 97fl2 k4vzsutxgc, pe;nrej0 z0 j7le food molecules into a complex structure. Is this a violation of the second law of thermodyn204left09kjzz7ec pv7ur sj,4; neg xamics?

  An ideal gas expands isothermally, pek: 1 idc9kmpcl zw(az-)y0gj :k7 cgz3rforming $ 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 urt75;dvf/8:efuk v c and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is obsee:u utrk/8vf5cfd ; 7vrved 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 atn1hs 9 iab w/ t/qr24pngd(.xh constant pressure until its volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the procwn9h rngpi(qs a//hxb2 4t1 d.ess on a PV diagram.

Sketch a PV diagram of the following process: 2.0 L.d39i mfzii 2a txtn;, of ideal gas at atmospheric pressure are ct niz;m39 idfx.a2 i,tooled 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 the original pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressurshsgf:/6 oq5 g+gkdr 2e 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 process on a PV diagram, incl/6o qg s hr+2gf:5kdgsuding numbers and labels for the axes.

  The pressure in an ideal gas is cut iu,5 gxl 4pljmse0e83 )m :8kloh6yfx7yq3 nsqn half slowly, while being kept in a container with rigid walls. In the process, 265 kJee)6gkx3q,7803n y84q5m ufjms : yxl lps loh of heat left the gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas is compressed adiabatically to half its volume 8 9u*5ysatmiu. In doing so, 1850 9 ayi5mu8*ust 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 atm from 400 mL to t6 -+wf 6bqh1t gs3sy;var6dt660 mL. Heat then flows out of the gas at constant volume, and the pressure -gd6 6ftshtw qtyv1rb; 3as6+and temperature are allowed 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 expandga0-x-eo;sctp bn.z7e2bkldxo;( ;x d2lfm + adiabatically, performing 7500 J of work in th a+s0k-xcfbogl 2om pxzlnd (btex.7;2 ;-ed; e 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 out o;mc y 2 5 oifnm r8hhhg0uwb8,*nxg/q2f an ideal gas at constant volume so that its pressure drops from 2.2 atm to 1.4 a ;wnc8h *b/r fhuq,g52mmo 0ny8gxi h2tm. 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. 15–23 shows two possible stati u4dt4 9h/p7th*wob mes of a system containing 1.35 moles of a monatomic ideal i7bhp d4*h4ou9 /wmtt gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to c along the curved pathqp )1 rz *dvrsd4niunx:)vf/ qm6,+ml in Fig. 15–24, the work done by v1 4f) ,m/m q6:nidzvu+q)pxlsdr*nrthe gas is $W\,=\,-35\,J$ and the heat added to the gas is $Q\,=\,-63\,J$ Along path abc, the work done is $W\,=\,-48\,J$
(a) What is Q for path abc?    $J$
(b) If $P_c\,=\,\frac{1}{2}P_b$ what is W for path cda?    $J$
(c) What is Q for path cda?    $J$
(d) What is $U_a-U_c$?    $J$
(e) If $U_d-U_c\,=\,5J$ what is Q for path da?    $J$

  In the process of taking a gas from state a to state c along the curved pat/jypap t58-br333awiayngur5or. m3ng2 : y yh shown in Fig. 15–24, 80 J of heat leaves 85 bntu2ary p-wp y3j3on53ga:yyrm g3/ir a.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 15pg 4bqa z52+za–8 transform if instead of working 11.0 h she took a noontime break and ran forzbz4p q2aa+5g 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, sits at a /(hy0 ox uiti5desk 8.0 h, engages in light activity 4.xh5o(u/i0i yt0 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 one hour 3xsavm t) )c.xi( j9alless per day, using the time for light activity. How much weight (orscv(tlji39)xax) am. 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 hjmb0m ux 4cs /fc:uy18eat while performing 3200 J of useful work. What is the efficiency of this enginef0m1u8xm b/:u c4 ycsj?    %

  A heat engine does 9200 J of work per cycle while absodjn6 z-z.ai1 yupcdf 7f50-kbrbing 22.0 kcal of heat from a high-temperature reservoir. What is the efficiency0 ju-.b5fi17pf - dda6cyknzz of this engine?    %

  What is the maximum efficiency of a heat eng 9/q*rr :zv/ v0ctutupine whose operating temperatures are *rvut rtp/z9: vucq/0580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heaveqcz **q,a9e qwj);dt engine is 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plantbbsos vk. +)d- operates at 75% of its maximum theoretical (Carnot) efficiency between tempe+ovb sdkb) .-sratures 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 enu/:jq2ai *0jsp wnhy*vironment 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 tempera:qhi ju w**sp/n0jy2ature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs woz zl7l 4dj- yirs.s.5prk at the rate of 440 kW while using 680 kcal of heat per second. If the temperature of the heat source is 57s 5i4zlydl.7r sz-.p j0$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating tempqnnxtf)pa/5q/eic 3;eratures 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 y6q/bx)z0 iy dheat discharged pe0xyz) by q6/dir second, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat sour) fgoqc* xbcca regc3a+w7*h8 l +q1t7ce 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 heat at 350vla85f.1o ek cod 1yx;$^{\circ}\,C$ 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 work in pairs, the output of heat from o03q*8n d3fhx/e+.xyoggj,+qk bgb z y ne being the approximate hea 8* +gx n0qgg xjqfebzboy.+k33/,hdyt 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 -1 kquc -wup.(gw5g1f hiub9*1)sm q/yw5$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates with x7ozw1wlhg 1j/z/ ,gja in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance off w79:g7cml :e57smha gp7sax 5.0. If the temperature in the kitchen outside the refrigeratol7 mex :ha75f pm7gsc7a:gs9wr 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 wa m-jt.ekra), zrm 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 akhxm ixz6;g kb/d 21kqow8u5 y:*3 eurt 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 effickqyokwhn e(bo* 823 +kiency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficientoq*y3h nk28ewbo+( k k of performance?   

  What is the change i/wrn l n6ek*wv zmw.((n 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 water is heated f;*q eyum3 wv- 8f 1)efbnjb0icrom 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in p;mee4q c iiki di36q9o1pu(+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 in * ru34 7g+jowpug0c6ceqvh s4itial 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 the ground and lf:ul7i8q8kw 6irikl)cd +9pz6 o pqu,x38bvcoming to rew8:ld kqu6 9 xk o ,iql)ucbf irv7+838p6ilpzst. What is the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conducts(n-cd.eb- j w6kw 0rzd $7.50\,cal/s$ 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 30er*c831yb l+eh3zh5br0 x ufl$^{\circ}\,C$ 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 alum9qk ;ul6- vgfqinum 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 workint3 asvbn2-uhm+ 0.:ewu7myong between heat reservoirs at 970 K and 650 K produces 550 J of wmmvabu h+n o ut2- y.w:3n0s7eork 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 probabilitiegvo8+ cs -+x mpbm*bduy3r49k 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 order of increasing probabih4s+ nj7zk,v.og6vuj lity: (a) four aces and a king; (b) six of hearts, eight of diamonds, quu ,j g. svnhv+jz647okeen 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.

  Suppose that you repeatedly shai.kftn.3k /ha ke six coins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate. What is the probability of obia.khk .n /ft3taining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can p-z5p(l1 bmgij 7rt, knroduce about 40 W of electricity per square meter of surfacg5l-17 m(,z rbtnpjkie area if directly facing the Sun. How large an area is required to supply the needs of a house that requires $22k\,Wh/day$ Would this fit on the roof of an average house? (Assume the Sun shines about $9h/day$)   $m^2$

  Energy may be stored for use durinb5ka +5 0fpu3a1sctvfg peak demand by pumping water to a 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 +03u fbacs p55v t1fkathe 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 d*ovvag8l6aau)gy i,* am (Fig. 15–27). The water depth is 45 ,iv*a )yo gv*8aag l6um at the 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 designed and built an engine that produces 1.50 MW oll0xuffub ao g(m:nno*e8-m1)u d :2jf usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting 1.5bm: 1g(e a: *nlf20df j)uxu8-un molo0 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 0- acm4zgp7zc of 0.25 and delivers 220 J of work per cycle per cylinder4gp0m-z7 czca . 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 reveasr8 ,micg //zrse of a Carnot engine) absorbs heat from the freezer compart8crsm/g a,iz /ment 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 a heat engine could be developed that made 9a))4b 2+nyuya umctruse of the temperature difference between water at thec)4u nuyaty)m9+ a2br surface of the ocean and that several hundred meters deep. In the tropics, the temperatures may be 27$^{\circ}\,C$ and 4$^{\circ}\,C$, respectively.
(a) What is the maximum efficiency such an engine could have?    %
(b) Why might such an engine be feasible in spite of the low efficiency?
(c) Can you imagine any adverse environmental effects that might occur?

  Two 1100-kg cars are traveling in opposite dmvo+wwei ;d irku0(/: l8 .rxoirections when they collide and are brought to rest. Estimate the change in entropy of the universe as a resul(i0:krm +8lurdwe.i; wx o v/ot of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated alumi+lbtw7 q- cfwa2w-8jig w:j0ynum 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 heat p zdh ;dxn3:ctac* waj q;ctz +-.j+ch*ump that extracts hn3c ;wt*dth+ qc.xaz;dha+c-j c z *:jeat 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 imys87 p4yrzxtk5 k7n,n a car releases about $ 3.0\times10^{ 4}kcal/gal$ If a car averages $41km/gal$ when driving $90km/h$ which requires 25 hp, what is the efficiency of the engine under those conditions?    %

  A Carnot engine has a lower operatt/1 ijcsnk 9z/19 fjsling 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 Fig.;08ak 6 -y 1*g 1k lcryusdh;oi7xapkf 15–28 for each of the following prophxdyr1 86-0yg;*cuoakkk71 ;a slifcesses: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Co-a71vjyvccy l,; zeq 3bq:fv; oling towers aq71vj3 fe vbcylvy;a;q:c , -zre used 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 st3 wk 3i91;+onm/ skyaylx b,gzeam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 yn g; x33k,9kmab1w/yi+os lzK. 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 aogcckm*(uwk2ll/ w 7; t about 15% efficiency. Assume the engine’s water temperature owclk7;/c o *mg(wul2 kf 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 7; rks zof3rl56y)rc, 6lisao 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 fatj9ona ;0c9 sh-hl3nmdl5)ym6ceowk- results 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 roo.vtv 8t.(oh gcm 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 essentiallyun9 uae; .ldj/ 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 condensation of 9uend/l;.ja u 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