What happens to the internal energy of water vapor in the air that condens0 mba4vv:j5e e ro.h;nes on the outside of a cold glass of water? Is work done or heat ;4nhb5aoj0 .v emevr:exchanged? Explain.

Use the conservation of energy tofe d 35ddk834z tzror; explain why the temperature of a gas increases when it is quickly compressed — say, by pushing down o d;kf 4zetddrrz5o3 38n 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 ;d leayczcy63;+ dn+kthis enough information to tell how much heat has been added to the +y6l+;k;a nc edzcyd3system? If so, how much?

Is it possible for the temperature of a system to remain constant even thoughzv30(/q3 7z(x jjtvxqqhioex05e5a b heat flows into or out of it? If so, give one or two qq03 j5 5i((bvx 0ee oztqjxxv73haz/ examples.

Explain why the temp4kv8un nga2vc3tf 9*g erature of a gas increases when it is adiabatically compressg 8u2a*vnc3gvn kt94 fed.

Can mechanical energy ever be transformed completely infxwol+b ai(/s/,7 tyyto heat or internal energy? Can the reverse happen? In each ca,/il xf/ stoyb yw+a(7se, if your answer is no, explain why not; if yes, give one or two examples.

Can you warm a kitchen in winter by leaving the oven djwbec8;qn;94 hsl 5ay oor open? Can you cool the kitchen on a hot summer day by leaving the refrigerator door open? Expla8q9ajn;h5c l eb4sw;yin.

Would a definition of hexdp(6*71ixr nwxqn s lm;6d0cat engine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature anlmb.;) v+4tnd -/x bg8fuzy nvcwmd3:d low-temperature areas in (a) an internal combustion engine, and8.gn b/m:z;cw3 dlfm- )+v4xyv udntb (b) a steam engine?

Which will give the gren;at gm 5vx-w6ater improvement in the efficiency of a Carnot engine, a ; vnw5x6-at gm10 $C^{\circ}\,$ 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 (inl55k e7 gxe)xnternal) energy. Why, in general, is it not possible to put tg ke5n)5xl7ex his energy to useful work?

A gas is allowed to expand (a) adiab.9 f-cj3n kfh o2z,aheatically and (b) isothermally. In each process, does the entropy increase, dfczn ke32-h ohf9j ,.aecrease, or stay the same? Explain.

A gas can expand to twice its original volume eitheb4 hkkvnix// h xei 07k)kygz;m)1yp 9r adiabatically or isothermally. Which procesn4yykh 7/0m9i) ixk/e1k zg; b)pxkv hs would result in a greater change in entropy? Explain.

Give three examples, other than those men-dx p+eznnx5 +tioned in this Chapter, of naturally occurring processes in which order goes to dip5exndnz x-++ sorder. Discuss the observability of the reverse process.

Which do you think h46 b w3j1e,,lsajz t18b2bkgp4bn a lias the greater entropy, 1 kg of solid iron or 1 kg of liquid iron? l4la3b16i ,s, bbajn4pbzew2 j1 8tgk Why?

(a) What happens if you remo,7sphm pt0 t-kr aml17ve the lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or wpl7kmth 1p 7rt0-, amshy not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-rbt79c-4cyv:k f:qc o loom air conditioner”: a big box, standing in the middle of the room, wytl4qv:c 9k -fb7:c coith a cable that plugs into a power outlet. When the machine is switched on, you feel a stream of cold air coming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than those alreadyuds1mipa.;k/c 7* z zj mentioned) that would obey the first law of thermodynamics, but, if they actually occurred, p/j u czazd.;is1k*7mwould violate the second law.

Suppose a lot of papers bgn(2*.ybp khmz mazcrt7:a g7+3s)gare strewn all over the floor; then you stack them neatly. Does this violate the secondzzb7h( a*. k2:yg sp nm7g+ma)cgtbr3 law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stated as, “You ca e4a+k, gg1frjn’t get something for nothing,” and the second law as, “You can’t even break even.” Explain h,jk e 4ggfa+1row these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because it tells hd;t+- 9xwsdv us in which direction natural processes occur. If a movie were run backward, name some processe dt-wxhs+v; 9ds that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert relatif 94:f)f an51szizjivvely simple food molecules into a complex structure. Is this a violation of the second law o49sif5fn a: fvj)1 izzf thermodynamics?

  An ideal gas expands isothermally, performine k3uabqcny:dkeb3:1kzgpl 55) ou3 2g $ 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 lig)vd,a :lefmw rx8z;i0hy3n5ynv m9s.ht frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the v8. fymxizdvrl m,9)w3an; n 0s5yeh: 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 cool .iga9j xd93pxed at constant pressure until its volume is halved, and then ita9gxp.xdi 39j is allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following process: 2.0 m.rio98*; pnvs *( gcizbceo*L of ideal gas at atmospheric pressure are cooled at constant pressure to a volume of 1.0 L, and then expanded isothermally back to 2.0 L, whereupon the pressure is increased at constant volume until the orig;e*imb**zp.o8vino (r9c gs cinal pressure is reached.

A 1.0-L volume of air initially at 4.5 atm of (absolute) pressure is (6 tauujax0fwg:v7k 8 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 uw:ku670j8g( avtf a xby 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 cutsmxdsk-(a iwj 6o((m - in half slowly, while being kept in a container with rigid walls. In the process, 265 kJ (s-s io6wkm (- jdxam(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 adiaba lgf8g* pc1 pz+f:ym10uk6kcv tically to half its volume. In doing *:c mpvy18kfg61f+gp kzlu0cso, 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 atm from 400 mL to 667uknwr+*x58l-xc 8.fou ewohih+j8 p0 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until ihn*k+ oxl xefo58 +87puuw8w- r.hjcthe 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 ia o+,tn;vvsz.f2rsetcf4u ca/w8)1 f deal monatomic gas expand adiabatically, performing 7500 J of work in the process. What is the change in temperature of the gas during this expansion?4fur vcf8) ceazf,.wt 1v/n +;st 2aos   $ K$

  Consider the following two-step procjxlg 8* 7hx)s+k5mwcdess. Heat is allowed 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*dshlm 8c5 w)g+k7xxj, 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 containing 1.k;c pe75sth)e( ms-rn35 moles of a monatomic idealse tc7e5m )- hn;(krsp 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 qyqc7bxux0wk v*kkad91 /hh :.b(m 6ithe curved path in Fig. 15–24, the work done by the gas ak*y km9.:/b(quvdqcxbk x0 1iw7 h6his $W\,=\,-35\,J$ 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 path sh(*2 trb97c1jvdkfz8 9c)2 eymrltdspown in Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on the system.9yp2cs(t vb)e* tcr2k7djz lrf 189md
(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 tuq;)mxnk i5rzpk 5b 3,he person of Example 15–8 transform if instead of working 11.0 h she took a noontime brezx35q m5bn, ukr) p;kiak 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 g mee20epn 9q *x5jsk7,izg.w desk 8.0 h, engages in light act7 x2ie ,0wg*qmepg.nzj59s e kivity 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 byag(gah/;0, ppb9eikxy dvz1 + sleeping one hour less per day, using the time for light activity. How much weight (or mass) can this person expect to lose in 1 year, assuming no chang/a0 xgk9bd;zyhv( pga,e 1i+ pe 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 usefuhcud1hw1 cnx+- +e1kyl work. What is the efficiency of this enginehx1 w1 ku cy+hdc+en-1?    %

  A heat engine does 9200 J of work per cycle ol45(q4ri7 aff cl cs3while absorbing 22.0 kcal of heat from a high-teqo3lifa4 (r s4c5f7 lcmperature reservoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temperatureri5sh+ep8/+y/ bw) zby6xu gq s are 580rhb5wsqg 8+ )b/puxi /yyz+6e $^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine is6.vg:wb(l, g oj9yv:w4e mu/o ujxrs0 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 vev9w1a cp q-r2ov)un+3u 6zq(Carnot) efficiency between temperatures of 625r-2 nazvu+ 9u 6v)e 3w1qovpcq$^{\circ}\,C$ 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 environmconur v 7.+qs)ent be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the efficiency ouo+).r7scv n qf 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 of 440 kW while us: y(. 2ozay/ wk0pzpdoing 680 kcal of heat per second. If the temperature of th:wpz2a p.0y/ooyzkd( e heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temperaturxh )79xfm:fx yes 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 heat dischk*:n8pdd ; 2x t9luguearged per second, assuming that the plag duu n98pxtl2:ekd;*nt has an efficiency of 38%.    $MW$

  A heat engine utilizes a he yx fdr+ -7+(r/g7wjk iy1fypqat 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 heatf )jo.8sd6oz* hjor/x 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 / ge:lkptmsv8y*xi9)x -u y9pwork in pairs, the output of heat from one being the approximate9xkepmy g 98up*l/xt- y:vi)s 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 -15+qb,58j0c(xv l uynrv$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-free *2y/jl)gfijt zer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficipl0vyi5 u-0a *cy.kx ient of performance of 5.0. If the temperature in the kitchen outside the refrigeratoru*5yxai0v0yl ikc -. p 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 k0dn rb6z zbv4xz+d( 8zeep 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 am86* xewrtasyh 9o)0 zt 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 efp(b*iktzxd4i.mm;es. nl+gpw h/6 i6 ficiency of 35%. If it were possible to run it bac*mz/+h6.e.gi w(64kltni m x i;psdp bkward as a heat pump, what would be its coefficient of performance?   

  What is the change in entropy of 250 g c9e.o n.xijvza83giej ; z29a of steam at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of watexz9kh e69a1c;uzj1rs.)j i sc r is heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy c; )s2 moyxkusl8 -4;h0 kvfcnof $1\,m^3$ 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 havinge1 rhcp5tq l,*o/k)5w r. uqex 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 striq o xhyf+qk-74king the ground and coming to restox7y -fkhq +4q. What is the total change in entropy of the rock plus environment as a result of this collision?

  An aluminum rod cond1xnynmai28 + gucts $7.50\,cal/s$ 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 30ovga p.9)k2*bynt8 ;hfu nc u:$^{\circ}\,C$ 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 a3ye,npeleg yu0)n2)+fsmq cgt7 tl/3t 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 reservoirg a.6 dc(37iybz9isda s at 970 K and 650 K produces 550 J of work per cyclbd.7 c is39a6ydia(gze 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, wh 7e r5 fky+xmptng*3v,1voyx;en 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 handsj5, npn9 yk4s w/ai9h4j+ ogmr in 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, ,npjy9srk5ng+ a 9i4jmh4w/ oand 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 w bkak)2iblrh3.k2 :nshake six coins in your hand and drop them on the floor. Construct a table showing the number of microstates thabh ib2 n2akk:lw.r3)kt 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 electricity per square w 4/2jft nj 0c2r wzpnc)vxq..a+p ku-a3itw (meter of surface area if directly facing the Sun. How larg(t+ixw 03a-arptp24 . zj /c.wv2 qfknjucw)n e 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 during peak demand by pumping water to a h7iu*jty v+p7v igh reservoir when demand is low yiv u*77p vjt+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 .udiw:(nfqe m)1g/u6lo 1 gxh dam (Fig. 15–27). The water depth is m :1d1glfg 6ehuiun q( .wo)x/45 m 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 +rr h i78k7ssi2fgse61.50 MW of usable work while taking in 3.00 MW sis7 6i782skr+h rf geof thermal energy at 425 K, and rejecting 1.50 MW of thermal energy at 215 K. Is there anything fishy about his claim? Explain.  ----待选择----yesno 

  When $ 5.30\times10^{ 4}J$ of heat is added to a gas enclosed in a cylinder fitted with a light frictionless piston maintained at atmospheric pressure, the volume is observed to increase from $1.9m^3$ to $4.1m^3$ Calculate
(a) the work done by the gas,    $ \times10^{5 }J$
(b) the change in internal energy of the gas.    $ \times10^{5 }J$
(c) Graph this process on a PV diagram.

  A 4-cylinder gasoline engine has an efficiency of 0.25 and delivers 220 J of w4swb waq,i9 3oork per cycle per cylinder. Whes 9w3aqbw o,i4n 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” refrigerato8ok0ur 3: nlomr (the reverse of a Carnot engine) absorbs heat from the freezer nuo:38 lr0m okcompartment 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 hejl/fv:bjly6./p s5* -pn m fmqat engine could be developed that made use of the tempe/j6yjn:pmlsmf.f 5qp- l/v *brature difference between 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 in opposite directions when they s;-l9 yct ;ggjlfe+uj pn l 7bp9g7)0dcollide and are broug9bud;p+ytc0l97;l gn j g splf)-gj7eht to rest. Estimate the change in entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum cup at voawft0 fds 5md)/ ;,o15$^{\circ}\,C$ 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 coeffici,yo7s6ii se+g ent of performance of an ideal heat pump that extracts heat f, 6 ssego+7iyirom 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 moe3 /zoemze3w90+ey +j kt5ov8 hdg8in 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 lowerw;py3y ko4qm 9-scg*r 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 gas in going from pi8zf m9fh s;i046 p:nl,z tjpstate A to state C in Fig. 15–28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC dire p40s:phzjm86 ;ftfnz 9,piil ctly.

  A 33% efficient power plant puts out 850 MW of electrical powu5z7q kou*nm 8er. Cooling towers are used to take away the exhaus*qk5o 7un8 mzut 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 deliverszpm3a u7, q9f48 myecd4a 3syg energy at 980 MW using steam turbines. The steam goes into the turbines superheated at 625 K and deposits its unused heat 43a,sc7gpy4z mu m8fdye3q9a 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 qj k9hoad 7 tsi(k-b*)wdpgf4 i+4)d mabout 15% efficiency. Assume the engine’s water temperature od4 )fg sbod(ik4*+dhtq)9 aik p-mwj7f 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 rhaf7*euf ety-c(3 s:,; lsgrvw2ih+ a 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 fatjwd7d7wiabrs4-d u.d/( 4 kll :coy6y 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 room a7f;n.o:7f n-leap pe ht 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 essent: 1umop bj1vtnws m;67ially 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 woj: smv n61pb17tu;mrefrigerator 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