What happens to the internal energy of water vapor in the air that q)3u:ol uqyn*condenses on the outside of a cold glass of water? Is work done or3 q u*onylu:q) heat exchanged? Explain.

Use the conservation of energ u,y,:l.f hc, bjn)usty to explain why the temperature of a gas increases when it is quickly comp) s h f,tu,.n,l:yucjbressed — say, by pushing down on a cylinder — whereas the temperature decreases when the gas expands.

In an isothermal process, 3700 J of workz+i,yn (s,*lt+qpxo ttae58 p is done by an ideal gas. Is this enough information to tell how much heat lpot+x tqy5ne ps+8(za*,t, i has been added to the system? If so, how much?

Is it possible for the temperatci9h8ty*hlt w7 ,5g xjure of a system to remain constant even though heat flows into or out of it? j5 *t7c,9ytwihg xlh8If so, give one or two examples.

Explain why the temperature of a gas increases when it is adiabatiwyk/b2i 7g l6ycally compressedw kyiy627 /gbl.

Can mechanical energy ever be3sc q)+bh)td k 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 one or two examples.th)d)3+s bck q

Can you warm a kitchen in weg7e t:lven-z+ m 9 loul7w(epn4a h84inter by leaving the oven door open? Can you cool the kitchen on a hot summer day by leaving the refrigerator de8n +ho4t lvzega-m :4eln7p 7elwu9(oor open? Explain.

Would a definition of heat ej5 alv0ilr(4wngine efficiency as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas .r 4xrnz/:tluin (a) an internal combustion engine, and (b) a stea/4xu.r:zlrn t m engine?

Which will give the greater improvement in the effici1 ve+jnz82hgh ency of a Carnot engine, a 1 8n+j v2geh1hz0 $C^{\circ}\,$ 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 (int 8jix o+ke 20/ulay-znsbrbro,c+v,6 ernal) energy. Why, in general, is it not possible to put this r k 2/+8iycu- ,6anxo+os0brlezj,bv energy to useful work?

A gas is allowed to expand (a) adiabatically an9 0fn oil9oz tvs d6h1rq1-r1nd (b) isothermally. In each process, does the entror09d 6r-tls9 von 1izn1 q1ofhpy increase, decrease, or stay the same? Explain.

A gas can expand to t lrm8q.y/zryxryu /5 ;wice its original volume either adiabatically or isothermally. Which process would result in a greayuy x/lr zr/y85mr.;qter change in entropy? Explain.

Give three examples, other than those mentioned in this Chapter, of natural.u 4z*idm .szuly occurring processes in whid.* u zizmsu.4ch order goes to disorder. Discuss the observability of the reverse process.

Which do you think has the greater entropynbqf)5y6)9utz-oba k , 1 kg of solid iron or 1 kg of liquid iron? W-fny out ))bqa9bz6 k5hy?

(a) What happens if you remove the lid of a bottle containing chlorine gas?aqx*g/61bwa9zs9 s yk (b) Does the reverse process ever happen? Wyx91b/9 as6*wa gqk szhy or why not? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that the inventor calls an “in-room air condjkb5yb fo m .v1330vrpitioner”: a big 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 mvyr3m0bbp.31 okfv5 j achine cannot cool the room?

Think up several processes (other than those already mentiod9 edq c:kcbttd3n4 n(8.n4q oned) that would obey the first law of thermodynamics, but, if they actually ocq83cdq4b4 tconkd n :.en9d( tcurred, would violate the second law.

Suppose a lot of papers are strewn all ovetuzl4jcl)j 5v0b+zucy 64.w bu1b ,uvr the floor; then you stack them neatly. Does b 4z4 bb.u u)j6y0vvzt5u+cc1lulwj,this violate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically stated as, “You can’ixn/ikg 0w9z7t get something for nothing,” and the second law as, “You9x 7/wkgiiz n0 can’t even break even.” Explain how these statements could be equivalent to the formal statements.

Entropy is often callwmo 3+6yt5eoled “time’s arrow” because it tells us in which direction natural processes occur. If a movie we 563wo yomtl+ere run backward, name some processes that you might see that would tell you that time was “running backward.”

Living organisms, as they grow, convert r; si9*4wok3i04b ; eafzyu nkwelatively simple food molecules into a complex structus kkfn4*z aww4ui30bo9;ye i;re. Is this a violation of the second law of thermodynamics?

  An ideal gas expands isothermally, performiklk3+caa j-p9ng $ 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 -(- 4qxg6mzf0ovcirlcylinder fitted with a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to themg q-xlov(4c0f- i z6r gas, the volume is observed to increase slowly from $12m^3$ to $18.2m^3$ Calculate
(a) the work done by the gas .   $ \times10^{5 }$
(b) the change in internal energy of the gas.    $ \times10^{ 6}$

One liter of air is cooled at consim ie b2*6v-cytant pressure until its volume is halved, and then *v c2b6 iymei-it is allowed to expand isothermally back to its original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the following 4i0jf.jm d:x.cyqq pf30nndql6ij8:+kh ;kiprocess: 2.0 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 th0nd6lj 38j iiqm 4qh0+dpic:k.;.xy jnffq:k e 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 (absolutemmu f92g,k2mil0h5 j.sz7/hl,l*wsuk wy3 il ) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constant pressure to its initial volume, and lastly is brought back to its original pressure by heating at constant volume. Dh,uy7k2ums,.i msi / *j5l whl03 wl9m kzg2lfraw 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 being kept in a co ycx.oks8 xgx7n) mmu*,k;4pnntainer with rigid walls. In the prn8 p)s u4.m cx *x7k,xyongkm;ocess, 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 adiabatically to half its volum u h.eqww;mw/1ul cla5ax) ,r1e. In doing so, 1850 J of work is done on th/la);wru,ecalux w1 q5m .h 1we 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 ar*g2sg(-jl uids2r 1q constant total pressure of 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure and temperature are allowed to drop until the temperature reaches its originuild *g2j(-s1rsrq 2gal 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 idevsl8 5osp hc: o0xz-5qal monatomic gas expand adiabatically, performing p 8hc z-:ov055sxqsl o7500 J of work in the process. What is the change in temperature of the gas during this expansion?   $ K$

  Consider the following tw:/ h- a2by2tuz gesz*0;ezmhk o-step process. 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, from a volume of 6.8 L to 9.3 L, where the temperature reg2*ku;0-/2z ma:z e thehzbsyaches 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 show81tt1cqxsdw6o ; gq m8s two possible states of a system containing 1.35 moles of aq86 1to1xqd g8scmwt; 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 to c along the curved path in Figvvq2dh2r2 ua mzdx9 4*pq27ig. 15–24, the work done by the gas 42p qq *v2ardvzuh72dg2 9imxis $W\,=\,-35\,J$ 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 ar:k6uba) otz4 gas from state a to state c along the curved path shown in Fig. 15–24, 80 J of heat leaves the system and 55 J of work ist kra:u 46ob)z 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 13thdy h7y 5/his5/v*+vyqe xoi4x 5d lzsg61h5–8 transform if instead of working 11.0 h she took a noontime break and ran for 1.0 h?dsvh5v7 qxyhtd yi5hxz *lys435/go 1/ ei6+ h    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleepzy,qku3 ra*l2/*aic2bc mfi)s 8.0 h, sits at a desk 8.0 h, engages in light activity 4.0 h, watches te*2ck/l ,3)i byrci2amafu qz* levision 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose wewbjr1-9vql v7.eyze l(nak +/ight by sleeping one hour less per day, using the time for light activity. How much weight (or mass) lnwe r9zq/ayk(1l 7ve.j v-+bcan 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 whglx9ou 1/xy6vnjb j04ile performing 3200 J of useful work. What is the efficiency of this engine? lv 0xbn6x1jo4y /ugj9   %

  A heat engine does 9200 32zmc nvb0.ne g +6dhpJ of work per cycle while absorbing 22.0 kcal of heat from a high-temperature reservoir. What is the efficiency of th 0cd pnvg+3e6hbmz.n2is engine?    %

  What is the maximum e11;wa v eec*fvfficiency of a heat engine whose operating temperatures are 511e vfa;ewc*v80$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine is 230q,p 6n7n uyto1m6te j0$^{\circ}\,C$. 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 t nfxat(0+)jsdh ..dyi+ -aj hzheoretical (Carnot) efficiency between temperatures h0fs xy dtja)i+da.h-+n(.j zof 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 engi8d5w1jzh r(h vne’s hot environment be hotter than ambient temperature. Liquid nitrogen (77 K) is about as cheap as bottled water. What would be the ef1w8(drh 5vhj zficiency of an engine that made use of heat transferred from air at room temperature (293 K) to the liquid nitrogen “fuel” (Fig. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work at the rate of 440 kW while using 680 km n5ux :u1 jos+)jze:wha7g4w cal of heat per second. If the temperature of tzewoauu 4g1s x)j+:hm5 :njw7he heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating yrwm 2;n30)fmwneroqgp9a7; b58wpl 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 ovr8 jt+c pw .a*n(huu9f electric power. Estimate the heat discharged per secpt .( awjr98nvcu+uh*ond, assuming that the plant has an efficiency of 38%.    $MW$

  A heat engine utilizbogl)w7po ma ce )8l*x-;qn*kes a heat 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 exhausr2xn rt3rgp) 9ts 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 engines work in pairs, the output of h8 uc)3-eaqoy7.bw )ee jpx*hteat from one being the approximate eh)bw7e38tyj)qx - coep*.au 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 -: 1w7s.8krbi9oufnrf15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freevtkmg;tcx*;)er6s3rr - u+ r kzer operates with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator hgeyu7 sd .wi55;eb cy0as a coefficient of performance of 5.0. If the temperature in the kitchen outsidcu e; ysbgde7 iwy05.5e the refrigerator is 29$^{\circ}\,C$, what is the lowest temperature that could be obtained inside the refrigerator if it were ideal?    $^{\circ}\,C$

  A heat pump is used to keep a hou9xfq mtr zj785se 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 water3y2nggyzh/hs7t (vf0 at 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 efficiency o,mjz/jbr gi1(rzk), 3 pg:lx af 35%. If it were possible to run it backward as a heat pump, what would be its coefficient of p:(bg1, pa xjm)jz ig3zrr/k ,lerformance?   

  What is the change in enu :w7+ )apeu vvv+lhe4tropy 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 i;c vzc yp3r;3 mnuwy8,s heated from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropyy q il(w9 hsld.3:lgi0 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 a5i 2v8wqpo3)-pzt+t/qbs+z l lw v/ ispeed 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 KEqbp:eyp 3eghnm/1yklw4 9z/ ( just before striking the ground and coming to rest. What is the total change in entropy of the rock plus environment ( :3bny wklq1/9eg p4ep/ymhzas a result of this collision?

  An aluminum rod conduct*2maf ao ml2w9s $7.50\,cal/s$ 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 30y1 odhzpq6e6 )$^{\circ}\,C$ 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 alumiqo.pejp 6+ vi ,usa*m3num 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 betweelr (39sxa jy bazcdjh+(qb-/c8);rpaqu9 5 nrn heat reservoirs at 970 K and 650 K produces 550 J of 5(sn/9)p; ubjcc(9 8h3- x aa+jqrd blqrarzywork 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 probabil7 lue )qhgt l8bi *e82fwbbm5)okio4 6ities, 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 orde hn0hye 0z6wf9r 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; anh0w60f9nezy hd (d) any hand having no two equal-value cards. Discuss your ranking in terms of microstates and macrostates.

  Suppose that you repeatedly shake six coins in your hand a d18mm:3ia)8amelzx8 lan-yynd drop them on the floor. Construct a table showingm):yy d 8aa8-mzxe8lalni 13m the number of microstates that correspond to each macrostate. What is the probability of obtaining
(a) three heads and three tails,   /64
(b) six heads?   /64

  Solar cells (Fig. 15–26) can produce about 40 W of electricity per square mete8t+u nnsq9-gw pgu4xy: f/0zvr of surface area if directly facing the Sun. How large an area is required to supply the needs of a house that requires gt+qn9gs :nyuf-/u 4wp v0x8z $22k\,Wh/day$ 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 tob,a6 8cka0,tu) pvscw a high reservoir tca,w6spk)a uvcb80 ,when demand 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 b)oy))m0,3l s zimauzxy a dam (Fig. 15–27). The water depth is 45 m at the dam, and a steady flozx0 ))asu3myi )mz l,ow 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 oeyo9 vch k;813 /cga7zkn2p3k 8czqiff usable ygvk7fci 1a83q2ce kc no8/hp3z z; k9work while taking in 3.00 MW of 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 0.2r4 6--xc t libz:)+qpl p6n-dyfhmz43im e 6cj5 and delivers 220 J of work per cycle per cylinder. When the engine fires at -4z -tbqmnflyi 6dr4)jc3x:6le+ 6ci zhpm-p45 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 heo6t :q*x2m )hcc9dzzoat from the freezer compchc62x zt:dzm 9o o)*qartment 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 developedow 1 c-:qj)eug that made use of the temperature difference between water at the surface of the ocean and that several hundred meters deep. In the tropiu1 q )oc:wgj-ecs, 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 oppce sx5226u bzujz47hqosite directions when they collide and are brough6chz2eq2 xzsjb uu457 t 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 alit:,o36nbayw9/smx f0pse +wuminum 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 he+9v - 7q b.jqv;qwcj3jpuwq:ejt.bn8at pump that extracts heabnjw. j.8; :+q7wptvjq3-qj9bue qv c t from 6$^{\circ}\,C$ air outside and deposits heat inside your house at 24$^{\circ}\,C$?   
(b) If this heat pump operates on 1200 W of electrical power, what is the maximum heat it can deliver into your house each hour?    $ \times10^{ 7}J$

  The burning of gasoline in a car rel+ kwwbx69d-9b8 prcqj eases 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 operating temperature orh gim.5;qd /$T_L\,=\,20^{\circ}\,C$ 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 (tqo45l y r- l)n)akaiideal gas in going from state A to state C in Fig. l5k)4ra )oi q-na(lyt15–28 for each of the following processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 :o0ywjd( b6w0u iv q1q9xfm7aMW of electrical power. Cooling towers are used to take away the0x9o (iaym 1b6wqqwfu7vj:d0 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 pb0*ddv2hai ) ji /d(kat 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 turbine ope 2k0 )h/iip( ddv*dabjrates 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 elfkpum b4: c89:fe9ro ngine’s water temperature of up fk r8bco994: lfem: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 cyl6z 9euuy 6l 2s,4frzicindrical 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 m**oo z,ocsxck-bb 2 6of fat 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 keepdioys)zt9 :ihq8j6 9 ns the temperature 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 doo a2g;.y pzqi7/t2nd fyr.” The humid air idy 7 2q;2pgt i.yanzf/s 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 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