What happens to the internal energy of water vapor in the air that24en xdp9q-zp condenses on th9e 2n-xz dpq4pe outside of a cold glass of water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain whys ( khwa 5cz15wicwug;1 b4,yo the temperature of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whe5ccw y,uz5aogwshk; i11w( b4 reas the temperature decreases when the gas expands.

In an isothermal process, 3700 y:hu zx4l/ ug+J of work is done by an ideal gas. Is this enough information to tell how much heat has been added to the system? If suh/ :lxz +g4yuo, how much?

Is it possible for the temperature of a system to remain ce aw0a ;s5 qz*qdr+xa8onstant even though heat flosewaad5r;*qz+q0xa 8ws into or out of it? If so, give one or two examples.

Explain why the temperature of a gta0-tton9, i uas increases when it is adiabatically compressed,ti attn9-u0o.

Can mechanical energy ever be transformed completely into heat or invqd c z5en7:s.ternal energy? Can the reverse happen? In each case, if your answer is no, explain why ezn cs:v5.q7d not; if yes, give one or two examples.

Can you warm a kitchen in wintja t1h(ovfwkg2m9l2 5m5 pk+her by leaving the oven door open? Can you cool the kitchen on a hot 5kl2am v95g(pkw hf ho j21m+tsummer day by leaving the refrigerator door open? Explain.

Would a definition of heat engine efficiency as au, l23/7hbzrr bih/w $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areas i c*.spdp yrjm j/ue/q)3)dg 9dn (a) an internal combustion engd cugd /y.sp/*)jpqr3jdme)9 ine, and (b) a steam engine?

Which will give the greater improvement in the efficiency ofhbs,r () e3ernoj7dk,p .6x fi a Carnot engine, a j7k. x,6hfpeedri, )3r (onsb10 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremeqhxkdkdw j(z / 7pg(00ndous amount of thermal (internal) energy. Why, in general, hpkk7wz0(0 q / xjddg(is it not possible to put this energy to useful work?

A gas is allowed to expand (a) adiabatically ax9 yg bs+iq63apgp-8 lm rb)9hnd (b) isothermally. In each process, does the i s99albqby3 hpm p x-gg6)8r+entropy increase, decrease, or stay the same? Explain.

A gas can expand to twice its original volume either 0-)zpocymfy2l*3a xuk6 r/m madiabatically or isothermally. lycmzmpyr-af)uo / 30m xk2*6Which process would result in a greater change in entropy? Explain.

Give three examples, otrnglhq8n4n 34 her than those mentioned in this Chapter, of naturally occurring processes in which order goenl43nn8gr h q4s 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 n/zv99:ulo u48avg hw of liquid iron? olg w 4unvv9/haz:8 9uWhy?

(a) What happens if y n86u9y z ((yz.zgaqe.bfofg a71 +itnou remove the lid of a bottle containing chlorine gas? (b) Does the reverse process ever happen? Why or why not? (c) Can you t.yty zfznb(o6a9(g qeua 8z i7n+f1.ghink of two other examples of irreversibility?

You are asked to test a machine . dung.p9ti 8rlxsh56that the inventor calls an “in-room air conditioner”: a big box, standing in the middle of the room, with a cable that plugs into a power outlet. When the mach.u h lp5xris9d n.t8g6ine is switched on, you feel a stream of cold air coming out of it. How do you know that this machine cannot cool the room?

Think up several processes (other than those already mentioned) thatc gc.z v4bxf8kh) +f,hpt*g8m would obey the first law of thermodynamicm.g4xvf c* c)g 8hzh8k btfp,+s, but, if they actually occurred, would violate the second law.

Suppose a lot of papers are strewn all over th:rt(y4irpx7t e floor; then you stack them neatly. Does this viol4tp r7i x(ty:rate the second law of thermodynamics? Explain.

The first law of thermodynamics is sometimes whimsically staz xzc 087njq4nted as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain how these statements could be equivalent to the for70nx4j8zq z ncmal statements.

Entropy is often called “time’s arrow” because it tells ul74fhwiv a;m00pciqn;gbwpt1)8 x z7s in which direction natural processes occur. If a movie were run backward, name some processes that you might see th4 nb)xq8z mp 1t7 l0ww0;a; fphiigv7cat would tell you that time was “running backward.”

Living organisms, as they grow, convert relatively s* k30ajfuf/y-u lmtq3 imple food molecules into a complex structure. Iuuqyjm -l/*3 a3f f0tks this a violation of the second law of thermodynamics?

  An ideal gas expands isothermahdchr+f v0 4hlr ;5dproj-s5 .lly, 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 friction v hnp:vhxmy/-0f7m6b sem1u9less piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, vm-pb7 h9/u6xmhfe :m01ysv nthe 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 constant press2rpm , )c:fvngure until its volume is halved, and then it is allowed to expand isothermally back to itc)n :vr2mpg,fs original volume. Draw the process on a PV diagram.

Sketch a PV diagram of the fol mlimaocg8013 lowing process: 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 the pressure is increased atl3oag0c8i1m m constant volume until the original pressure is reached.

A 1.0-L volume of air initially at 4.5 athzyy wkk+1 ud41nw 7s2m of (absolute) 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 constanwz+712wn1uy4k yhd ks t 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, whia*rv nb,mc f7*n fl;7rs9pqf *le being kept in a container r9fff7nrbapl7 *qm *v,*cs; nwith rigid walls. In the process, 265 kJ of heat left the gas.
(a) How much work was done during this process?    $J$
(b) What was the change in internal energy of the gas during this process?    $kJ$

  In an engine, an almost ideal gas is compressed adiabatically to half its vo,kpsc t -f973 cf5wzbqlume. In doing soc z-79c,pk bwq5sf ft3, 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 ,psniek i(xvx5w gm rd,se,i81h1;5o; q gh:rpressure of 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the pressure an1,hgnvsx,e5iqs r5dowikh;m, :gp( 1r ;xi e 8d 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 expand adiabatically, performinjlp*p4g-fabw7o7y.hl y6 s9 bg 7500 J of worklbsy 7*pfl6o hy4j-aw 9 pg.7b 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 out of x8x,jwbsh0/o l1be:v2p l r (gan 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 tb1ov8 / lj(g0sw exhrl,:xbp 2emperature 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 containingg*fg k330 hgrl 1.35 ghg 0krl33f*gmoles of a monatomic ideal gas.$(P_1\,=\,P_2\,=\,455N/m^2,V_1\,=\,2.00m^3,V_2\,=\,8.00m^3)$
(a) Draw the process which depicts an isobaric expansion from state 1 to state 2, and label this process A.
(b) Find the work done by the gas and the change in internal energy of the gas in process A. W =    $J$ $\Delta\,U$ =    $J$
(c) Draw the two-step process which depicts an isothermal expansion from state 1 to the volume $V_2$ followed by an isovolumetric increase in temperature to state 2, and label this process B.
(d) Find the change in internal energy of the gas for the two-step process B.    $J$

  When a gas is taken from a to c along the curved path in Fig.y;a e2gz1j l*s 15–24, the work done by the gaj1y; s2 la*ezgs 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 curvegfutd2 ssyv2*i 7f8:t iui (3td path shown in Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on the syste83 fs7utgu 2iyd*:if2tvt i(sm.
(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 inste f;r3.cvhjiy; lc:dx4ad of working 11.0 h she took vilyj;:f x hd3;4c.cra noontime break and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metabolic rate of a person who sleeps 8.0 h, -udrx0.3 5qdf7 6 iyn8jdvixp:qu2jw sits at a desk 8.0 h, engages 5-ijq3 pv06j w2: 8n.rfxdid uydx7uqin light activity 4.0 h, watches television 2.0 h, plays tennis 1.5 h, and runs 0.5 h daily.    $W$

  A person decides to lose weight by sleepi8tugy18s0;(d pm vuugng one hour less per day, using the time for light activity. How much weight (or mass) ca8gdp; g1u umyvt(08usn this person expect to lose in 1 year, assuming no change in food intake? Assume that 1 kg of fat stores about 40,000 kJ of energy.   kg(retain one decimal places)    $lbs$

  A heat engine exhausts 8200 J of heat while performing 3200 J of useful wnhmoac43bdm+ )z r76 tork. What is tt7m3aozndc 6rh4 b)+ mhe efficiency of this engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal of heat fl4n3 ftys9;vp rom a high-temperature reservoir. What is the el9sn p3y4t v;ffficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose sy jd5uo7 tx68operating temperatures are 5j6 57syduoxt8 80$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature ofd(g7xvi.z 7ciwv/ow28 f9hyw a heat 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 theoretical (Caqw)dn;q t ex--rnot) efficiency between temperatures o-;qd)xq nt-wef 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 environment bq- f,q1k4 xegi4txq:/ ustdn4e hotter than ambient temperature. Liqu /i un-et4g d4 ,4txksq1:qfqxid 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. 15–25)?    %(Round to the nearest integer)

  A Carnot engine performs work ef: c/cjs ;a1xx 8ljz)mmy3 lc8v)(tn at the rate of 440 kW while using 680 kcal of heat per second. If thcvx1cm)8e/:ny a;)s38t(x jl l cjmf ze temperature of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating tem 7:6dn oriq5pxntb9 4mperatures 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 7ekd0g0ilp i p pb)lz+en60 1opower. Estimate the heat discharged per second, assuming that the plant 6obli7ep0n lgp0kdpi)+10ez has an efficiency of 38%.    $MW$

  A heat engine utilizes a heat sou 1e-g 6rhp.w(yksh*qh 9r)x9bj *d hbi6w/kbrrce 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 *1qvxziza;y v5+5*apdrmczct m05d/ 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 engineympn-q- n j04 uqw7o,js work in pairs, the output of heat from one being the approximate heat input of the second. The operating temperatures of the first are 6o-j n4-n,j7 qp0mqyuw70$^{\circ}\,C$ 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 cool*nzoul ,51 sefing coil is -15$^{\circ}\,C$ and the discharge temperature is 30$^{\circ}\,C$. What is the maximum theoretical coefficient of performance?   

  An ideal refrigerator-freezer operates )0u/ po0(vgerfq so- pwith a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coefficient of performance of 5.0. If the tempe2e8(ery: 78xmm.98km kfxp tegdg+dfrature in the kitchen outside the pmxffe8 7.+x89 gd trg2ke8k (yedm:m 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 house warm at1 )ox1v(pht6b0vx.iqvgvt ; q 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 atkexcm, ,b 7t5zt 7)xvw 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 of 35%. If it were : bac* qcmvzv. /lth6,possible to run it backward as a heat pump, what would be its coefficient of performan.6/ v hccav,t:*mlqbz ce?   

  What is the change in entropy of 250 g of steammti*61xf2(v vwfxfth8:icw 5 at 100$^{\circ}\,C$ when it is condensed to water at 100$^{\circ}\,C$?    $J/K$

  One kilogram of water is heate5ld(d;miu5 (m.m ib pfd from 0$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change inu/s3pymz l,4*en +v4x n(sdwm 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 spee6jfw +ux-bu:y d 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 en(m,f lg3us 6wcergy KE just before striking the ground and coming to rest. What is the total changu 6sm3,cwlg( fe in entropy of the rock plus environment as a result of this collision?

  An aluminum rod conduc-x md n:,uhnq1ts $7.50\,cal/s$ 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 30b+k9zc e ttwf,69c:).jewul 6dwr .pu$^{\circ}\,C$ 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 aluminumb k52ea k:o8st 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 betw;yc:r;mo/ 2x*yx0 hzf zyqpm0een heat reservoirs at 970 K and 650 K produces 550 J of work per cycle for a heaxomm hrfy0y z0*;;x:2 zyc/q pt 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, when you throw two diojpgtxy/ pxa2y ia26 0)z6j4 gce, 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 probabildxsx uk9z (tz *3cs(6uu7 r7zajbo f./ity: (a) four aces and a king; (b) six of hearts, eight of diamonds, queen of clubs, three of heartz9.c((zj 73/*u rba 6zuf7soxds k uxts, 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 repeguwoee9 0j0:q atedly shake six coins in your hand and drop them on the floor. Construct a table showing the number of microstates that correspond to each macrostate.u0:jw9qeg0e o 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 4e;k9c .aiof(p3 ff12kg yp0 wq0 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 house tiak9cgfek;ofwp .21 30q(fp y hat 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 u4syydiz r(ispf-8n4 1 se during peak demand by pumping water to a high reservoir when demand is low and then releasing it to drive turbines when needed. Suppofyid-n 4(p814szs riy se 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. 1x8ec u*)/bic t 6za0mz5–27). The water depth is 45 m at the dam, and a steady flow rate ofm)e/cxzza 6 0cu*tbi8 $35m^3/s$ 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 enginr)c4 tqks8 95op wyo4 ukv7b*he that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting rqw*so9otb485vk4 )p7 h kycu 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 ajn pr /bhq-tyz1(.q8 gn efficiency of 0.25 and delivers 220 J of work per cycle per cylinder. W-zbn/p8 yj( gqt. h1qrhen 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” refrigeratohkp0a3f,b.6ct .go adr (the reverse of a Carnot engine) absorbs heat from the freezer compoh,.k .actb3fpdg 0 6aartment 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 madeoe 58i6:i-r a;pz, upbtezqb/ use of the temperature difference between water at the surface oru;:e6 qt5e bbz,-i/io p apz8f 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 trk y*) -a feg-pvfcvh7h)t-kc4aveling in opposite directions when they collide and are brought to rest. Estimate the change in-phfc- fekvk-)v *gth47a)yc entropy of the universe as a result of this collision. Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum kh-rf3v :xh 2f7zjo(qcup 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 pump that extracts h6ob.2 bzkoq0e eate qo b026kb.oz 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 cml09rtg 9yz1 uar 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 ope k8d/mp+mitrk+1e: rm rating 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 sta ja 3oyaekctap43 346ote A to state C in Fig. 15–28 for each of the following processes: (a) A a3c6 4tjk ao4y3aepo3DC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puu4wiuyulz) rmh1-j 82ts out 850 MW of electrical power. Cooling towers are used to take away th)yuiz r8wujh1u m4l- 2e 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 stet otyzab3vv)-s-n (g0am turbines. The steam ba)0t3--zo gyts vnv (goes into the turbines superheated at 625 K and deposits its unused heat in river water at 285 K. Assume that the turbine operates as an ideal Carnot engine.
(a) If the river flow rate is $37m^3/s$ estimate the average temperature increase of the river water immediately downstream from the power plant.    $C^{\circ} $
(b) What is the entropy increase per kilogram of the downstream river water in $J/kg \cdot\,K?$    $J/kg\cdot\,K$

  A 100-hp car engine op4bq itp h/yx+l, wxl;o40 qnvg.o2vx/erates at about 15% efficiency. Assume the engine’s water temperatu. htx;vx+go xlqo/wbqi /2l4 ny vp4,0re of 85$^{\circ}\,C$ is its cold-temperature (exhaust) reservoir and 495$^{\circ}\,C$ is its thermal “intake” temperature (the temperature of the exploding gas–air mixture).
(a) What is the ratio of its efficiency relative to its maximum possible (Carnot) efficiency?    %
(b) Estimate how much power (in watts) goes into moving the car, and how much heat, in joules and in kcal, is exhausted to the air in 1.0 h.P =    W $Q_L$ =    $ \times10^{ 9}J$ $Q_L$ =    $ \times10^{5 }kcal$

  An ideal gas is placed in a tall cylindrical jar of cr5n /)oi: awdevoss-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 resula6ig k6a 4pxlw,i.9xy6h:ac2 *bqhr l ts 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 temperatu.xh i wn0rj4,clat )ghy mz7.9re 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 lfq9.m:j 6zu. avkqnt/a2 5ifwith 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 water vapor to liquid. Estimate how much water is removed in 1.0 h by an ideal dehumidifief 9i. qa t: ajuq2m6n./5vkflzr, 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