What happens to the work done when a jar of orange juice is vigorous4h6hbggh 0cz ozfzo,6 y/l/am4vh: s.ly shaken?

When a hot object warms a cooler object, does temper )jvf; rl3( n7m cfilct v4p*f,/r;ludature flow between them? Are the temperature changes of the two objects eq;4(3ft;v*c / uicpln7frrfl)m, ljvd ual?

(a) If two objects of differenqb xdc8q5kccn2 g-s1w 7.qs4ft temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to s7qbf.qwqg2s5x8d4k 1c -nccthe object with lower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperature may d0;e gbj6kd)fnur)q1j rop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in k; e j)qrjn0fdu61)gbthe evening. Explain.

The specific heat of water is quite large. 8 ;xls2ky :grwavi k.0i ug,;fExplain why this fact makes water particuigk ;:r,;ukg a 8y.xvw lfis20larly good for heating systems (that is, hot-water radiators).

Why does water in a metalop(9cl fzpj:7i5w i/l canteen stay cooler if the cloth jacket surrounding the canteen is kept moistlw izc(o p/:plf759ji?

Explain why burns caused by ste-+ pcj3ygld h5st1 ads1w5hp(pd3z 9dam on the skin are often more severe than burns caused by wat(d9p1 -5g d31d+chp tdsjh3s ywa lp5zer at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the ra vk5: 0/k*w9tbit-clnnr0 kconcepts of latent heat and intew ki :0/t50vatk*-nlrnkbcr9 rnal energy.

Will potatoes cook faster if the water is boil( zikm5fzbtg1-c8mf) du: k4ding faster?

Does an ordinary electric fan cool the c92 ;gb2bqzvn-d)rwf ;thea6m1 hdaf c5, n8h air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the tem1yv 2- ekem2wjperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived.-5 z x:tw:b4kenmxib by covering themselves with snow. Why we:b n-:wk.i5b4xt zxmould they do that?

Why is wet sand at the beach cooler to walk on thz1 g z :g82fc9cjmh6dhli)(zyan dry sand?

If you hear that an object has “high heat content,” does thv1zm08l8jjgey x w4jx:.:pd kzr q ::hat mean that its temperature is high? Ex:ljy0:8p1 wkjzme. g jrd x:h4x:vz q8plain.

When hot-air furnaces are used to heat a house, why is it important that thewhkh dl /e q.zby1 ua/)k7vz*0re be a vent for air to return to the furnace? What happens if this vent is blocked 7z. zuk hk//*db wv0elh)qy 1aby a bookcase?

Ceiling fans are sometimes reversible, so that they drivnf/:rrw 2 su:ve the air down in one season and pull it up in another season. Which way should you:fv 2r:wr/nsu set the fan for summer? For winter?

Down sleeping bags am0t8o80o+ z7h2 akv )ctdhzvznd parkas are often specified as so many inches or centimeters of loft, the actual thickn0z zh0vo m+ 2hcta7t8okv)8dz ess of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that l a w*1zsw9vmh0h,pn q75a m9stooks like a series of fins. Why is it shapmt0*sw az q5 s99p7 mhv,anw1hed like that?

Sea breezes are often encountered on sunneb e/l:(du b/p j5w0twy days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more rbu b/(:e/lp e d5w0tjwapidly than that of the nearby water.

The floor of a house on a foundation under which the ab8htmq(d;bxt3q(9bind/r ;p ir can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foxi d n(t;dq8bbtph;mrq (b/3 9undation). Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature readings are always taken with the thermometer in8 vn *u6blpd,m the vb,md8un*l 6 pshade.

A premature baby in an incubator can be dangerously coolokypr/,e tgyb 6/;kyf4 v s aol,/,)jmed even when the air temperature in the incubator is warm. Expla,mkry /tl;pf kv /ego sbj/oa,,6)4yyin.

Why is the liner of a thermos bottle s( s5tmre;ai8 pkdu/e-ilvered (Fig. 14–15), and why does it havetd8( iua e;-k r5/msep a vacuum between its two walls?

Imagine you have a wall that is verd4tr3 4uf 6zeqy well insulated — it has a very high thermal resistanc 3er4t6uq4zfd e, $R_1$ Now you place a window in the wall that has a relatively low R-value, $R_2$ What has happened to the overall R-value of the wall plus window, compared to $R_1$ and $R_2$ [Hint: The temperature difference across the wall is still the same everywhere.]

Heat loss occurs through windows by the fol f;ty3zo,t):8 di fplilowing processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or rzy dl;ft38,p)i:itfo adiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun abso8ghlo b :c0af;rbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pickb8g;0 ol:hcfa it up. Explain.

The Earth cools off at ni y zk2mz-fr:d6kpo0dbd m58c,ght much more quickly when the weather is clear than when cloud2kzm 06p-bcf :d,zdkdo mry 85y. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Exx0:uipv8gp6.qoq)e4n a;nuwhy 57 nn plain how it can help to vn4o g . 6)nwqp7 xpi0uq;8hnne5ayu:keep an immobile person warm.

Explain why cities situated by the ocean tend to have lepo7xt57h0gf 4 i( *vsui +5 0tyklwtjmss extreme temperatures than inland cities at th jv(*iwh5 m05txg i7 p7uo04y sf+kltte same latitude.

  How much heat (in jouleptq 9,h 1,f7;o y*jpaaa rdr0js) is required to raise the temperature of 30.0 kg of water from 15 p yj dta* 9h,;qf7p1o0,arrja$^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raisp1ye3tsylx vc;j:( / re 3.0 kg of water that is initially a yy/:tev;j1(rlc xps3t 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal sd (jks:u3x+m a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of heat in the British s7fos3*;j pn4hhys e(-ydak04agvnv9 ystem of units. One Btu is defined as the heat*p aa4 - s9vvd0ose yy;g37(4nkfnj hh needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genec e++xenpd -u 9hqtp6/rate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated at 350 W.gwqa gbk8em be:9ku y -se-,76 Estimate how long it will take to heat a cup of soup g9-e:ky86es b 7,-umeb akgwq(assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bring a 1200-kg uu4eiwp 8qznyj8 .)9e car to re eupqewiy.8n 4j9 zu8)st from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water,ym(az/d y 9a5jb iyaoyzpu+cipb4k,5b7- j: . How much heat does it absorb if its temperature r-abi9:z4m ci jk( 5p y+yz5,/, uo7bpjdy ybaaises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a meo1xp-s *ype n5tal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 18.0pp-1oyx se5*n $^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminaup7- wmshii,9i a 2+gum, and water experience the same temperature rise when they abs-miwpi+hi7s,a2g9 u aorb the same amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rea) nudfb:k.bf4t8 a 0hhds 21.6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equl/h iqsoaha x0 k.h..b+om9i 7ilibrium temperature when a 245-g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe 5 c2h1au1fyo w(mass = $0.4\,kg$) just forged (Fig. 14–16), is dropped into 1.35 L of water in a 0.30-kg iron pot initially at 20.0$^{\circ} C$ . If the final equilibrium temperature is 25.0$^{\circ} C$, estimate the initial temperature of the hot horseshoe.    $^{\circ} C$

  A 215-g sample of a substa )i9l0u6cr5zxs d)zb lq ;*nrhgt z:*rnce is heated to 330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffeepot to bring to a boil 0.75 L ofvodvm (scns))6 mz-y7 water initiallyc)7m6nvdz sso -)m(vy at 8.0$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 7)my w24y;ujzmcgxl. g of candy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 km g7u2ym )yxj4 c.lwz;g. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron atx-/ kv3btm p*)thoaql ,b6g. d 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has a speed of k r0u+xy e2n0bvnq-v8 $6.5\,m/s$ just before it strikes a nail (Fig. 14–17) and is brought to rest. Estimate the temperature rise of a 14-g iron nail generated by 10 such hammer blows done in quick succession. Assume the nail absorbs all the energy.    $C^{\circ} $

  The heat capacity, C, of an object is defined as the amg(eu 8* hagy l9sgf/j.ount of heat needed to raise its tempy/glsha. u9e 8gj(g*ferature by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melt 16.50 kg of silgi; bmtz* 4tqi 28n;maojq1)j ver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-hci *tdpg 4.id0igh building. If 65% of the thermal energy produced when it hits the groun. d*ci0ipdt4gd is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evapor u*k7vq.qgp z t4;p /.qelsdy4ation of water from the s z*q4/ d vqe;.pqskt7ul 4yp.gkin. How much water has been lost?    kg

  If $2.80 \times10^{ 5}J$ of energy is supplied to a flask of liquid oxygen at -183$^{\circ} C$ how much oxygen can evaporate?    kg

  A 30-g ice cube at its melting point is dropped into an insula.efm o*8cq/ nt24 zjkimxz-.l4 fun7pted container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a late exq74. p2fl .zkc zm*-ifm8 n/jtno4unt heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is takts,k r-rw8f.z :yt k(6b ep:)xp-hjcgen from the freezer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains 830vw75 kl+o7 cgh kg of water at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, mt;7uy/;wd;60ol2 er moe wqma bicyclist consumes 8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, t ym ew;m2dwl em;6q ;oou7/0rmost of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam a nn+tlim/)jw7xxul m h9o) 2;yt 100$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of merfmyo6 gd26t:m hs7j :hcury is $138\,J/kg$$\cdot\,C$ Determine the latent heat of fusion of mercury using the following calorimeter data: 1.00 kg of solid Hg at its melting point of -3.9$^{\circ} C$ is placed in a 0.620-kg aluminum calorimeter with 0.400 kg of water at 12.80$^{\circ} C$ ; the resulting equilibrium temperature is 5.06$^{\circ} C$ .    $ \times10^{ 4}$ J/kg

  A 70-g bullet travelibs/ v7 +/cyg;m4g wkvnng at $250\,m/s$ penetrates a block of ice at 0$^{\circ} C$ and comes to rest within the ice. Assuming that the temperature of the bullet doesn’t change appreciably, how much ice is melted as a result of the collision?   g

  A 54.0-kg ice-skater moving aty weq8;h8qk2n $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic eim zg u9z/6-rinvestigator notes that the 8.2-g lead bullet that was stopped in a doorfre9zu i -m/z6grame apparently melted completely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2.0 cm i- e *k7)auynixzg-ka0s kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow.s v f-l0uspwr 9s:3zw by conduction in Example 14–10, assuming that there are strong gusty winr9 zv s0u:ws.w3 slpf-ds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere021hj 5f q.wzuqrl*js (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W o . ;mqrb587opmvau+u lf heat flows by conduction from the blood capillaries ben b+ao8vm .;u7 lumr5pqeath the skin to the body’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per f b5jvz1 51hw9z d6w*tsfyaf-m*:dw; d l:wavside, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one rzwjv ba5d:ffwvf1-;6: dhz*w l 1w9ytsa*d5 moom, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a block of ice7 anvh k-t6;8l/ku7 mql2kodw at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same lengt -(: bfs nc,bggabt2x1h and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintbbsgc :x -t(1,bfgna2 ained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate at which the j) a(r*ggmm 3swhole Earth receivemgmja(gsr*)3 s energy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates c*6wi;,t j8 z8d;uvqips .spr95 W of heat, which is dissipated through a glass bulb that has a rad usw6rz;8tv p,ic. *dp;qi8 jsius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the waed 14 xmmzwr j0-v 1+h9xl6whcll of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, m v j1zxcwd0 hlxhe+41mw-r96if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separated by an air space, Fig. 14n4pto,lw uio69 3y .uzml32po–20. (a) Show that the rate of heat flow through such a i 3poo u3lutyw4m 2lp n6,.9zowindow by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long should it take 11.0 ge n7 ghq/qb+9kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0.20 kg of liqui-cvv4 x q7a7yhpiw i*5+o4o lcd at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much thermal energy is contained in the4o xjg)q -0vvf3 nene;1+lheh world’s oceans, estimate the heat liberated when a cube of oce)fe-x h0n vh v3 eqnj4l;geo+1an water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firu7ja1lpq,yx + ekg7pm o96ql7ing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, thp1qlp a79l g,7qk7j6ym ouex+ e system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power435vdhnba367sjsf-d 1.t 5 du vzb)iw7cczqs radiated into space by the Sun, assuming it to be a perfectu5sinc45w.-abqt)jdbf163sdz3 sd7vvzc7h emitter at $T\,=\,5500K$ The Sun’s radius is $7.0 \times10^{ 8}\,m$    $ \times10^{ 26}\,W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5 \times10^{ 11}\,m$ away (Fig. 14–21).    $ \times10^{ 3}\,W/m^2$

  During light activity,trkyzau.; y5rjf2 4 zln8. l1l a 70-kg person may generate $200kcal/h$ Assuming that 20% of this goes into useful work and the other 80% is converted to heat, calculate the temperature rise of the body after 1.00 h if none of this heat were transferred to the environment.    $C^{\circ} $

  A 340-kg marble boulder rolls off the top of a cliff and falls a vertical heigh 0e:wib,64s;hxtg qie nac,y/t of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the qies:n6e;ctxw,h g,/ia4 0yb rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water initiall.1si3dc ogq b*y )*bqh*ve( ppy at 20yep) 1h bgci3**qsv(.pqo* db.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears (**d wj,q7 oy)slbpe/ be;ilq a goose down jacket 3.5 cm thick with total surface area qebjpyi*w(o* qble , ;lds/7)$1.2\,m^2$ The temperature at the surface of the clothing is -20$^{\circ}C $ and at the skin is 34$^{\circ} C$. Determine the rate of heat flow by conduction through the jacket
(a) assuming it is dry and the thermal conductivity k is that of down,    W
(b) assuming the jacket is wet, so k is that of water and the jacket has matted to 0.50 cm thickness.    W

  A marathon runner has an average metabolisf 2eu kt*2d:iy r 61hla(jls8ym rate of about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which heat can be conda:1t6+ekxiz6hsst.5 q xbxv c;a l6/e ucted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, th6 vckb/sta1 it:.xx6sqe6;z+axl e 5hat the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thtpo2iv) hs4) yick (assume conductivity of air) and arevpo h2t)ysi4 )a $410\,m^2$ a roof of wood 6.5 cm thick and area $280\,m^2$ and uncovered windows 0.65 cm thick and total area $33\,m^2$
(a) Assuming that heat is lost only by conduction, calculate the rate at which heat must be supplied to this house to maintain its inside temperature at 23$^{\circ}C $ if the outside temperature is -10$^{\circ} C$    $ \times10^{5 }$W
(b) If the house is initially at 10$^{\circ} C$, estimate how much heat must be supplied to raise the temperature to 23$^{\circ} C$ within 30 min. Assume that only the air needs to be heated and that its volume is $750\,m^3$    $ \times10^{ 8}$J
(c) If natural gas costs 0.080 dollars per kilogram and its heat of combustion is $ 5.4\times10^{7 }\,J/kg$ how much is the monthly cost to maintain the house as in part (a) for 24 h each day, assuming 90% of the heat produced is used to heat the house? Take the specific heat of air to be $0.24\,kcal/kg$$\cdot\,C$.    dollars

  A 15-g lead bullet traveling ata2(upr jet-i+ $220\,m/s$ passes through a thin wall and emerges at a speed of $160\,m/s$ If the bullet absorbs 50% of the heat generated, (a) what will be the temperature rise of the bullet? (b) If the bullet’s initial temperature was 20$^{\circ} C$, will any of the bullet melt, and if so, how much?    $C^{\circ} $

  A leaf of area $40\,cm^2$ and mass $ 4.5\times10^{-4 }\,kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80\,kcal/kg\,\cdot K$.
(a) Estimate the rate of rise of the leaf’s temperature.    $C^{\circ} $
(b) Calculate the temperature the leaf would reach if it lost all its heat by radiation to the surroundings at 20$^{\circ} $C.    $^{\circ}C $
(c) In what other ways can the heat be dissipated by the leaf?

  Using the result of part (a) in Problem 58,zt3t1v vt6n-6)pwt rc take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by)trn61w 6 tztv3 pcvt- the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters u 0upt38ndi,zthe Earth’s atmosphere. If its initial tempera ,0tzp3uudn8 iture was -125$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s crust increases about 1.0 yg(it,.zuvb+ 2)iuut C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit au k v ir3wdx5/s;p24oym7ix.j soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the w os27yr;4 vxw /id i.3xmpjk5uall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masses of.1nyd*b y9v,paye(c m ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person cksp jb.w k.+xentz 4/4an lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would tzbs+k.x. nt4wje/k p4ake for the body temperature to drop from 36.6$^{\circ} C$ to 35.6$^{\circ} C$ if metabolism were nearly to stop. Assume a mass of 70 kg. (See Table 14–1.)    s

  After a hot shower and dmk**zzz +uzkiw3- i a1ishwashing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at 1zmzi i+azuw*3zk*k - roughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a 6+kpocix x r2n22r:nf7u, nj9k ty,l5r0-W lightbulb is 65$^{\circ} C$ when the room temperature is 18$^{\circ} $C. Estimate the temperature of a 150-W lightbulb with a glass bulb the same size. Consider only radiation, and assume that 90% of the energy is emitted as heat.    $^{\circ} C$