What happens to the internal eneb 2g; pm:)( lh6sd( yweefht/lrgy of water vapor in the air that condenses on the outside of a cold glass of 2bwm tf(gey6:ep; ldh) hsl(/water? Is work done or heat exchanged? Explain.

Use the conservation of energy to explain why the temperatur4pl o5 /pd. z:xza2dxre of a gas increases when it is quickly compressed — say, by pushing down on a cylinder — whererap2odlx4:zx. z/ d p5as the temperature decreases when the gas expands.

In an isothermal process, 370;liyd5sh(ba( v d * bln*hm32e0 J of work is done by an ideal gas. Is this enough information to tell how much heat has been addh d 5i2*se ndlhby (bvl3;*(maed to the system? If so, how much?

Is it possible for the temperas.odo 258 lwe2x o5oekture of a system to remain constant even though heat flows into or out of it? If so, gi de2kwo 2.8 oxo55leosve one or two examples.

Explain why the temperature of a gas increases whsw l6g9 a u64h43q-ldl-emmh+l ixld5en it is adiabatically compressedhu slll 39l 5 --em446hd6dxa q+wmlgi.

Can mechanical energy ever be transformed compl;texqko0 kp*l/lqfw k/ a4,dd .l+ip;etely into heat or internal energy? Can the revl0qk.,4kl;*; t ol dewifa p+px/ d/kqerse happen? In each case, 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 door open?yqor -a(r(rt(ax qva3 od +5)n Can you cool the kitchen on a hot summer day(rn3yoqa(rx+o aq- )vt 5a d(r by leaving the refrigerator door open? Explain.

Would a definition of heat engine efficiencbfvmg947pauui3to ;;-( me en y as $e=W/Q_L$ be useful? Explain.

What plays the role of high-temperature and low-temperature areass ) jk+a0pvys8b b,., tbs/tsh in (a) an internal hpsbj.v t 0ks/+s8 ,bsby) at,combustion engine, and (b) a steam engine?

Which will give the greater improvement in the efficiency of a Caa*g m zeym,e1+rnot engine, a 1,* e m+mzeyga10 $C^{\circ}\,$ increase in the high-temperature reservoir, or a 10 $C^{\circ}\,$ decrease in the low-temperature reservoir? Explain.

The oceans contain a tremendous lui8s p0xlys x (e/+o;amount of thermal (internal) energy. Why, in general, is it not possible (+ypsxo 8l/ ;0xsuli eto put this energy to useful work?

A gas is allowed to expan5 tz :ogn t(xehrh)s;/d (a) adiabatically and (b) isothermally. In each process, does the entropy increase, decrease,;5h/no(e gst trz hx:) or stay the same? Explain.

A gas can expand to twice its original volume either adiabatically 0z f uejcl ug:m4y 84vs-3;upzor isothermally. Which process would result in a greater change in entropy? Exp4j-8upm4 ue0 :gv lzu3;zcsyf lain.

Give three examples, other than those mentionedh- ux2d+kbbkrhb *8 8j in this Chapter, of naturally occurring processes in which order goes to disorder. Discu +b k8jubr8dh2* b-hkxss the observability of the reverse process.

Which do you think has the greater entropy, 1 kg of solid iron or 1 jh zq4iz.o7jdczg (,+5b 8hrckg of liquid iroo,875i ghcbzcd qzr.(zh+j4j n? Why?

(a) What happens if you remove the lid of a bottle containing c 2opam(li39pr j)bwa,mq-3cnvkdt - 0 hlorine gas? (b) Does the reverse process ever happen? Why or why noamt)9 0, k2m rn- q(3bc al3wdpipo-jvt? (c) Can you think of two other examples of irreversibility?

You are asked to test a machine that:;mzs jpbu 0g* the inventor calls an “in-room air conditioner”: a big box, standing in the middle of the room, wizs:um ;gp*j 0bth 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 aicwfh1 ok18* e2 p53g9 zlfsuthan those already mentioned) that would obey the first law of thermodynamics, but, if they actuall8 9l g3asukez1ffp2ioch 5w1*y occurred, would violate the second law.

Suppose a lot of papers are strewn all over the fl- sbag,iq 692j f7sdrhoor; then you stack them neatly. Does this violate the second law of thermodynamics? Ex-2 h6b9ar g,dqssj7ifplain.

The first law of thermodynamics is sometimes whimsicazk*,:0nk4 fzm) (sb z:gyuchully stated as, “You can’t get something for nothing,” and the second law as, “You can’t even break even.” Explain h,fbyms cn(kg: ukzzu:) h*40z ow these statements could be equivalent to the formal statements.

Entropy is often called “time’s arrow” because itt4-;c2mewdxmtws x2x7m4f o jd6w**j tells us in which direction natural processes occur. If a o x2d7-mx6 ;swjmx4f4wc*tde2 t*j wm movie were 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 simple food molecules int)o5b7 bps j-8txqy 4 mzkj+j1to a complex structure. Is this a violation of the second law of thermod85tjt s1kop+ j zxb4-b)qj m7yynamics?

  An ideal gas expands isothermally, mj;fqig vy 09)6o xmy)d2mkq8performing $ 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 fd8cm o(5b7dugitted with a light frictionless piston and maintained at atmospheric pressure. When 1400 kcal of heat is added to the gas, the volume is observed 7cgu8(5ob ddmto 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:p9fmrmxrj8ta4t)buq3(j:uk b1t z6r f.m) led at constant pressure until its volume is halved, and then it is allowed to expand isothermally back to its original volume. Draw the process on a PV d6jarzt9 .br8mpj):(t:3 ub xfluf4k) 1qrmm t iagram.

Sketch a PV diagram on (7-6mil) o3m*wa:lsdo b tiyf the following 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 at constant volum im)ywmb* -i3oo(s6:dnl7 ltae until the original pressure is reached.

A 1.0-L volume of air initially at 4.5 atmpg iyy0f c2s1 9rkwm*7 of (absolute) pressure is allowed to expand isothermally until the pressure is 1.0 atm. It is then compressed at constantsw pmf*79c kyr g1y20i 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, including numbers and labels for the axes.

  The pressure in an ideal gas is cut in half sif 95iy80/cy 3i8hegzdx rcn yw.an;*lowly, while being kept in a container with rigid walls. Iwi;e5nyy g h.c/ icn0 39yzf88rax*idn 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 adz df s))i2;xhsif-k5 iiabatically to half its volume. In doing so, 1850 J of work is done on f)ik)x;sd 2ih- fs5iz 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 kkrffubcqbqps1s0h h4::*/ ( pressure of 3.0 atm from 400 mL to 660 mL. Heat then flows out of the gas at constant volume, and the h1 brh s pkcf /:0:quf*(4ksbqpressure 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 expand adiabad5t jsk008-zwtjmzbn( g7d9x tically, performinb m-09n zgt( dj jk0t8d57wszxg 7500 J of work 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 flq2yn;p5h zh3)gowk4 u0 5udq dow 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, qy4kd) hu5zop quw50n;h2gd 3 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 om(m *5(b r ujjhgco,9 49tbnmhf a system containing 1.3b c54 9*u jmg((9,jthbr mhmno5 moles 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 2c/l xu1sy,vh1d,k vv,mn r( min Fig. 15–24, the work dov 1 ,hmvyd1,v/x(c ,nr skul2mne by the 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 frf/tb,e wnem2ty6/keqk *c;: xom state a to state c along the curved path shown intmce x,ye/n t*;:6bqkf we/ 2k Fig. 15–24, 80 J of heat leaves the system and 55 J of work is done on the system.
(a) Determine the change in internal energy, $U_a-U_c$.    $J$
(b) When the gas is taken along the path cda, the work done by the gas is How much heat Q is added to the gas in the process cda?    $J$
(c) If $ P_a\,=\,2.5P_d$ how much work is done by the gas in the process abc?    $J$
(d) What is Q for path abc?    $J$
(e) If $U_a-U_b\,=\,10\,J$ what is Q for the process bc?    $J$
Here is a summary of what is given:
$\begin{aligned}
Q_{\mathrm{a} \rightarrow \mathrm{c}} & =-80 \mathrm{~J} \\
W_{\mathrm{a} \rightarrow \mathrm{c}} & =-55 \mathrm{~J} \\
W_{\mathrm{cda}} & =38 \mathrm{~J} \\
U_{\mathrm{a}}-U_{\mathrm{b}} & =10 \mathrm{~J} \\
P_{\mathrm{d}} & =2.5 P_{\mathrm{d}} .
\end{aligned}$

  How much energy would the person of Example 15–8 td)a 6j*s4 pf)mz3eshsransform if instead of working 11.0 h she took a noontime msa4)hed s3)* sjf 6zpbreak and ran for 1.0 h?    $ \times10^{ 7}J$

  Calculate the average metfaa7lw o4 k7 djk:dp,30ic)bqabolic rate of a person who sleeps 8.0 h, sits at a desk 8.0 h, engages in light act)a bd:, od7kl 0iw aq7jf3c4kpivity 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 bg- iwy7n 7lzc zw*w;( cq92rlby sleeping one hour less per day, using the time for light activity. How much weight (or mass) can this persongwcczwqi (l;7lwr2y7*n- 9 bz 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-a ydgu5do9 s;b-96t9x jreku 3200 J of useful work. What is the efficiency ofyg ak5- 6t u9 sxb-ojd9ue;rd9 this engine?    %

  A heat engine does 9200 J of work per cycle while absorbing 22.0 kcal of heat , sqv1u:2s.jmyhv;qz from a high-temperature resevszv;,y 1q:mu qhj2 s.rvoir. What is the efficiency of this engine?    %

  What is the maximum efficiency of a heat engine whose operating temperatures a5- t(r )ovgicqre (tog vi-5q)rc 580$^{\circ}\,C$ and 380$^{\circ}\,C$?   %

  The exhaust temperature of a heat engine j+olat5n.c sjw+x1.ois 230$^{\circ}\,C$. What must be the high temperature if the Carnot efficiency is to be 28%?    $^{\circ}\,C$

  A nuclear power plant operatp n08xx0s0eyywu 2, epes at 75% of its maximum theoretical (Carnot) efficiency 200 u e0pxwsenyx py,8between temperatures 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 environment be hottltj;l xd q*djl; p+(7jckf4u *er than ambient temperature. Liquid nitrogen (77 K) is abou*;djkjut;c*q(+l lfx74jdl pt 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 at the rate of 440 kW while using 680 kcal ofzqkte 9i;r g-7t5*rek2ld m2j heat per second. If the temperaturertlk2mk75;iej2*9gtrq d e z- of the heat source is 570$^{\circ}\,C$, at what temperature is the waste heat exhausted?    $^{\circ}\,C$

  A Carnot engine’s operating temp 4 dxzx2uh:lqfsf jy/5x 0*3zseratures 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 hefn8btgk- /t j7uvv*uqi ,u7o(at discharged per second, assuming that the plant has an effiguqo*7ti k vb,u/ fjvn( t8-u7ciency of 38%.    $MW$

  A heat engine utilizes a heabgq9zoxqi2 6x+c y-3v t 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 ;)h q3przu25* xh8p 6u7g6 ylni om,-rx mggqaheat 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 heat from ia)ehbg)p -a -v:icj*c d1o;c one being the approx)igdp-i1he bcv :*aa)-jo;ccimate 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 fz t5qrf0nuam. 7em;g;7u,zi cooling 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 ds0 oc3.whtr(k83;8wnghhe u with a in a 24$^{\circ}\,C$ room. What is the temperature inside the freezer?    $K$

  A restaurant refrigerator has a coeff qtk1ml.a;7n b9jgq2 9gly,l9y dji;nicient of performance of 5.0. If the temperature in the kitchen outside the refrigerator is lyaibg1q29 7 ykn j9dq .g;l9lt,n ;mj29$^{\circ}\,C$, 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 houzpzcep7* + i(x79y09v szziq 4u1gz prse 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 ymdltjq 20l5) 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 effi/8yctk6 6/vlekdqiv 9ciency of 35%. If it were possible to run it backward as a heat pump, what would be its coefficient of performance 86k ci v6//9tdkeyvql?   

  What is the change in enhcsa b6;i+y t ;a5btmk (we yr41,6lantropy 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 from 06g.erh)he:ey+se7)y ck o0e +dvy rc2$^{\circ}\,C$ to 100°C. Estimate the change in entropy of the water.    $J/K$

  What is the change in entropy ,,1pqk;rknd.nkg) a d 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 k0mh.7b(iurmy4 ( rpd3 cnsspm,dp5n3or5; o 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 beforez r4yj*q:)-q8u*w odi4bupqj striking the ground and coming to rest. What is the total change in entropy of th*: boj4iur q q jd4*zq8wp-u)ye rock plus environment as a result of this collision?

  An aluminum rod conductsjjrpe (x w63-v $7.50\,cal/s$ 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 3vq)ky )b k9t7bkx +ze(0$^{\circ}\,C$ 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 at 28cil ;g*pn dg30$^{\circ}\,C$ 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 resesh140.gvoxt 9yd t9 1q)*arjet ip7lv rvoirs at 970 K and 650 K produces 550 J of work per cycle7jea9t1*g y dvrp h490vt1t xs)q.loi 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 probabilit1h gh ;ohdq2tax0ppn :mr 10i+ies, 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 xq1chz3gey 04probability: (a) four aces and a king; (b) six of hearts, eight of diamonds, queen of clubs, three of hear0h 1 gyc3ezxq4ts, 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 shake six co* e8h3,;ivqkjc* kxj 4ulmu8 vins in your hand and drop them on the floor. Construct amv8c i*q3klj4;*,x8uv j ueh k table showing 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 electagvxaa -l8 l8v5c:q96 jvdwy9ricity per square meter of surface area if directly facing the Sun. How large an area is required to supply the needs of a house that ryv8:lgj6 dv85qvw 9al9ac-a xequires $22k\,Wh/day$ 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 high h m0y- ph6s08z)p:jco4 sfxxireservoir when demand is low and then releasing it to jh:86m)ipxp -0yzh4s0f x cso 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 csbzkcrc*m .*v4e2 h *nreated by a dam (Fig. 15–27). The water depth is 45 m at the dam, and a steackr*e n 2hsm* *.vcb4zdy 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 y6.9r2;l,srqje c:y z ng 9hnehave designed and built an engine that produces 1.50 MW of usable work while taking in 3.00 MW of thermal energy at 425 K, and rejecting ;2e,r.g9yy zrh n jlqn s:6ce91.50 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 et fgdi+h);d- ml- ysr+fficiency of 0.25 and delivers 220 J of work per cycle per cylinder. When thrdf;g )l- h +mdy+i-tse 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 rt1-nys.n9le 2) daes jeverse of a Carnot engine) absorbs heat from the freezer compartment at a tem eld9.nnst1 se j2)ya-perature 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 lnym e g,zaqw,k4b(:4 a heat engine could be developed that made use of the tempermnbw4ke:qy,zg,l4 a(ature 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 a*m.n,bn ap5g p j.)fe 6ymg /(t(quqnwhen they collide and are brought to rest. Estimate the change in entropy of the universe as a result of this collision.qb6.ng5a(m,epn*u.q(j m/fnt ag) yp Assume $T\,=\,20^{\circ}\,C$    $J/K$

  A 120-g insulated aluminum(5veundjh*d+h,vbs ; 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 h 3 /;msy2,3zc cr7:hx1achdiepl h pyp11zod 8eat pump that extracts heat from 6cy p7 3c13dza:x/ p h8y2 esm1hpohird;,l1cz$^{\circ}\,C$ 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 gasolindx; 1ey0; v5 cu(ykbjye in 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 operating0 hg.b5rk xb*w 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 anb2 hdf6m;qjwz-3y m (n ideal gas in going from state A to state C in Fig. 15–28 for each of the followifz3(w;6qbn -yj2d hm mng processes: (a) ADC, (b) ABC, and (c) AC directly.

  A 33% efficient power plant puts out 850 MW of electrical power. Cooling to521fchelcwaqry a .n*c./e 3owers are used to take away the exhaust hecwccf31h2l * rony/ eae. q.a5at.
(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 al yaorfs1j/ 03*q3 xzuwd-6drt 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 o01d /*3- yrosr6ulfwz 3jax dqperates 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% effici+ql 3xos(/f . ug6zpsaency. Assume the engine’s water temperature oaxg(f./p qz +ls3uos6 f 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 af:69 1x;3c jqklofz5cq.9 rvtnla m m: tall cylindrical jar of cross-sectional area $0.800m^2$ A frictionless 0.10-kg movable piston is placed vertically into the jar such that the piston’s weight is supported by the gas pressure in the jar. When the gas is heated (at constant pressure) from 25$^{\circ}\,C$ to 55$^{\circ}\,C$, the piston rises 1.0 cm. How much heat was required for this process? Assume atmospheric pressure outside.    $J$

  Metabolizing 1.0 kg of fat results in abouu, q/m5grkye ,,jhy(qt $ 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 ,qf nmcb hb+ hmm+sb u25)lo-8a 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 door.” The humid ai6-rnh:hw xn ( sveah- -u39ztqr is pulled in by a fan and guided to a cold coil, where the temperature is less -( h 3ztqhes- u-9hnn6vrwxa: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