What happens to the work done when a jar of orange *c 5xba384 j,wqei(h grnxnr /3v/rqdjuice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between th4 x6k xzqoc08mem? Are the temperatx4q mzc06k8 xoure changes of the two objects equal?

(a) If two objects of different temperatures are pn:b-jvxei 2hown rmz.-)r ,n(laced in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is itm hxbr2n je .v-on-:i)nrz( w, 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 bubzs)oplj 9:,e 0t4nppt the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering thelnt bzjpp0s),oep9 :4 m in the evening. Explain.

The specific heat of water is quite large. Expli tlm(qt ) fu314eka;fcmid ,;ain why this fact makes water particularly good for heating systems (that is, hqmilmuc),i;dea f t 4t31;f k(ot-water radiators).

Why does water in a mets.q9fer y+u5 jal canteen stay cooler if the cloth jacket surrounding the c+sufry j9q. 5eanteen is kept moist?

Explain why burns caused by steam on the skin are oft6r x p- lq8dj3c5tukvsh3b4a,en more severe than burns caused by water at 100 a3d56k48- s3xcbq,vup htjrl $^{\circ} C$ .

Explain why water cools (its temn* nmoi. r)0lgperature drops) when it evaporates, using the concepts of latent heat and internal enernol*gn0.ri ) mgy.

Will potatoes cook faster if the water is boiling faszyi9 bngu59 0+id .zfh*pmc6xter?

Does an ordinary electric fan cool the air? Why or why not? If no 8(+.6no tpyjnrn-3 b9zeqehkt, why use it?

Very high in the Earth’s atmosphere, th 8s/ b-dgsdlg2y(u ul(z,; viye temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering hicb8+qkji7o1 q*b*z themselves with snow. Why would they do thaq8 b1z 7bik*o chi*q+jt?

Why is wet sand at the beach cooler to walk on o(c)/h ttdp6xthan dry sand?

If you hear that an object has “high heat content,”-osd nvq z8- iokh 0; 54df;2aiur8tlh does that mean that its temperature is high? Explain.i h 8q;id-n-2du ;lah4 0o so5trzv8kf

When hot-air furnaces are us7wqbp6:o.o ;(y niatd p,l;a ced to heat a house, why is it important that there be a ventpy6noqiob :.lt ad w,cp a;7(; for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are som 3ee708ow-zbg(as9 nclb zwi )etimes reversible, so that they drive the air down in one season and pull it up in another season. Which way should you set the fan for summer? For winte ezg-iblc)n3aw7 w9 0sbeo 8(zr?

Down sleeping bags and parkas are often specified as so many inches o l5q*y9kp7ev3bzaqk. i ef: i4r centimeters of loft, the actual thickness of the garment when it is fluffed up. Expla4pvq9ke53eyzi b.7iq f:l *akin.

Microprocessor chips have a “hea re c4mk,dhp74yp 1wu,t sink” glued on top that looks like a series of fins. Why is it shaped,wruk p 4,m 7dc4p1yhe like that?

Sea breezes are often encountered on sunny days at the shopn :z3.) ywchire of a large body of water. Explain in light of the fact that the temperature of the land rises m nz ih:.cypw3)ore rapidly than that of the nearby water.

The floor of a house 4n g(ystt3czi: 0x:dwxo97; h,t9q-sg vg iajon a foundation under which the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Exps,jd 03cgiga:w9:qt 7tz h x4n xvyti 9-osg;(lain.

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 therm. * he qx aehuj7kyb+u3)n0qi-ometer in theux h)n .q*yiue0bjk-+h eqa73 shade.

A premature baby in an incubator can be dangerously coowxpby7/gum *,sy 1l7jled even when the air temperature in the incubator is warm. Expsyy1 g*7p bwm7uj,x /llain.

Why is the liner of a thermos bottle silvered (Fig *u6aazsyy + :g5qm4c5)x usun. 14–15), and why does it have a vacuua u65)amn:54usxq z +s cu*yygm between its two walls?

Imagine you have a wall that is very well insulate .8we-s (dd2l,d vymt46xczggd — it has a very high thermal rz6yw e.(8,4 ddgltmxgc-sv2desistance, $R_1$ 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 following proc+x,x jgc) 9 u5ppfu0wjiqt4/w esses: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the gq w 4wx5i)pjf ,pt+/9uu0gcjxlass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more 5bdklbu+ f,/mh0gt8 -ztj+ klp-em- k heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up.dkkl hp,jlfk- bm -/5bu+ge0m+tt-8z Explain.

The Earth cools off at night much more quickly when the svc,x oltsu7 wv d05edn p39,2weather is clear than when cloudy.p7 xuvndewv,, 2s9cdol s0t35 Why?

An “emergency blanket” is a thin shiny (metam7ny 9 cdiac8428m*as q/ tweml coated) plastic foil. Explain how it can help to keep an immomidts* e n8/ 79amyacw 24c8qmbile person warm.

Explain why cities situated by the o811jqege d ;m iq,-jxmcean tend to have less extreme temperatures than inland c,1 8qe -qjem m;1jixdgities at the same latitude.

  How much heat (in joules) is req .jmuce6kk q.d/ t q5fj 2f1w0i4m.zsyuired to raise the temperature of 30.0 kg of watmq 0. et. 4/.2dmfc5j6 q1yjuksfz wkier from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that yv8e 5rl- wn2k;r qnfh9mpd49is initially at 10.-qm f5rd v29yr np;9l4 whk8ne0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 C7l81otunq ha4q 1) xxgal 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 Britis( a b1jtwz tqvj63gb01h system of units. One Btu is defined as the heat b0b1zja3gvt1 (jqw6 tneeded to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can g a8dvcu5 4 4-;i1csbmsu;ti5wagmn4 9;lzxznenerate $32,000\,kJ/h$ 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 9(a hdk03jsee350 W. Estimate how long it will take to heat a cup of souahjee( s039d kp (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories art u6w/amr /ci)e generated when the brakes are used to bring a 1200-kg car to rest from a spwc tr/ /ai)u6meed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L oflz m-l+d0bv3ob.rk6 t water. How much heat does it absorb if its temperature rises from 0+ok rmzl dv6btbl-3 .20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is neededmd )lg n.ciyoxh,c0b-:*i 2 (: pwefyd to raise 5.1 kg of the metal from 18.i* fnh c)ipc:ydl0gyb :m x,- o2e.dw(0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature r .wt2p6 yvfec+ise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]cftpe 2wv6.+ y$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21am.vve - h.3rpfrs00)laf gfh 3jn(-s.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 equilibrium temperature when a 245-g block of copper at 28kyr7 raidjcm v, zoj1p k2k( 0*n97v(0xokq/n5$^{\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 horseshoepamywct7+as8z y / e vnk;3-)q (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 substance hd ax8oco.z+bac ,.c9is 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 to5 rsz:gd 7 kdq3*skndo9*osj( bring to a boil 0.75 L of water initiallydr (d 9:3zs5ok sngj7dsko**q 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 g of candy from the f19dtjyo+z5 b sz ue37kollowing measurements. A 15-g sample of te 1dbzy 9ksj3 oz+u57the 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 kg. 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 of4b/vd9i61d)tb cxg op iron at 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 *-d6rdqmdxwn* j51gsspeed of $6.5\,m/s$ 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,9b6:j:jntba mvnmx() of an object is defined as the amount of heat needed to raise its temperatuj(v9) nmb6mjbn:t :xare 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.unl9azofy)+d h 4;t)x50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the ro k /zd1lhr;fhd 1s)e:wof of a 45-m-high building. If 65% of the thermal energy produced when itf; sl ):1we /1zdkhdhr hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a p/j:yo9c t(sv a a2;umierson may give off 180 kcal of heat in 30 min by evaporation of water from the skin. How much waoiya2a cs(j:; tvm 9/uter 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 insulated codho l8)7vy)j pntainer of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K anv8 jdhy)p )o7ld has a latent 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 taken from the freezer at -tmmor*,n5t ..bd)fxtq p)ty) wyv8g(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 cont)cw-e vf.(crx8x f ox6ains 830 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, a bicyclist colrd,um 4vbni1:;l-fv xej (/ rnsumes 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 energydel rr,/blv:m;x4(n-jiv 1uf in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 10 gpn7:jwqj4p xsb5v,(mzs,0 t0$^{\circ} C$ 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 y uqb vvr7(xnym, ,u/gea15w*mercury 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 traveling l)/y: tprbao9 j.4v, (*on qwalq5gvwat $250\,m/s$ 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 1 kq2zh45 ;sgzlqw( fe;.qyiod/ xcj7 at $6.4\,m/s$ 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 investigator notes that eri n7x+t6/ hqthe 8.2-g lead bullet that was stopped in a doorframe apparenttnr6hx7q e +i/ly 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.kww8ce:*vd7gd zo ,pk)fjr* 7 0 cm is 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 by conduction iq:pnsnz;1 w5s n Example 14–10, assuming that there are strong gusty winds a:n15q ssw;nzpnd the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissdz 6 cxhpwn:cb3 xdu8y l7x-1s7 j2.fzivity $e\,=\,0.35$) 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 of heat flows by cozxp/( k cbt6yj 6dgcqb+/ 62ih+onpy ;nduction from the blood capillaries beneath the skin to th6 dcyqpg(/ h6; ++n6bczjpktb/yi ox 2e 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 side, share a 12-cm-thick bricw8o q*hi7 oxj 9o1;stxk wall. Because of a number of 100-W lightbulbs in one room, the air9qxx*sio ht 7o; 1ow8j 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 dm1z z9y3)ga kSun to melt a block of ice 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+w (kc yi6f6 za(yz3 .ng6wvgn length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a const wn+ycgf6 ny ak(zgi3z(v.6 w6ant 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 rayj h8q-j: 8p2v l3lbvq agx0m; m;lpw:te at which the whole Earth receives 2lvhmg0pq v:y8 x83w mp j;q:-a;l jblenergy 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 95 W of heat, which is dissipated through a glas;;,em,omo c qo.,*sgiyl4;ztt:mr nr s bulb that has a radius of 3.0 cm and is 1.0 mm thick. Wh o,s eic, ,;*q4m gmrtzm;;otlryo .n:at is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from a 4a9; s+b2j 2 yfrunmc yf6(m-wl.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, if its tota mwu r+y9b (ycl62f;n-mjsaf2l area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window haj z+ /mhd2te-pd 7lxl)s two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heapdlmhz7x dl-+)te/2 j t flow through such a window 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 shog7n haf j++h6ch*3l)zs; gblhuld it take 11.0 kg 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 krppl1k(z f,jpw z -2lz9iz7f 2g of liquid 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 7diagwu- dk cd8.b65kis contained in the world’s oceans, estimate t8iw5dcd b.-7ga 6ku kdhe heat liberated when a cube of ocean 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 firing it into a fixed b )uq,ai w)m.i2 qft8 pouys sn)7z:2cylock 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, the system has a temperature rise measured as 28qwsy) ic) su )i:mf aupq .ytz2on7,0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, asoivx *8l inu0*suming it to be a perfecov0* i*xnu8ilt 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, a 70-kg person g;g*ud6 ba:ijmay 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 vertiq oji 6sq(vvl78ov,*pcal height of 14(v qjovq76,o*sv 8 ipl0 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water iniigkc.:, )k kqnjk9m9.pb ai+ytially at 20.0k+iycpmajn .igqk:) bk,k.99$^{\circ} C$. 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 a goose down jacket 3.5 cm thick with total surfaca+b*v17.nqj 1 qdtptxg/3g twe areaag/d3xtnqqt.w *t1p b 1 vj7+g $1.2\,m^2$ 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 meiybw+ aka.,xln: qyv7ora8 9 8hnly7,tabolism 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 c0-yb io2yivn9onducted from the interior of the body tnib 2y yov9-i0o the surface. Assume that the thickness of tissue is 4.0 cm, that 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 thicka.u9q2d zkz q2 (assume conductivity of air) and area a2z .q9u zq2kd$410\,m^2$ 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 at 1.mjhev2cl,n* vwx*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 Probls jo8*-f,ktc :hb,s eiem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per,cbh :-,ef so*tsji k8 hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s at+ xbjzo1g 9nx:mosphere. If its initial temperature was -1g: o1xx 9+bnzj25$^{\circ} C$ 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 int ou /k0mk (+h8lwvhb8creases about 1.0 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 a soft rubber ball atyyuoz1cra jp,ny480 2 a wall until they are about to drop due to dehydratina8zj4y0yryo1u2p c , on and exhaustion. Assume that the ball hits the wall 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 r0wxtx66o v 8wzesult when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and radiation at a wgi iw*61n cz l4(geq+rate of about 200 W. Estimate how long it would take for the body temperature to drop from c ginil*z+e(14g 6wwq36.6$^{\circ} C$ 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 dn ;ab cjxz6s1+ishwashing, there is “no hot water” left in the 50-gal (185-Lj s6x1 c;nabz+) water heater. This suggests that the tank has emptied and refilled with water at 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 60-W lighph3 1j z6gq0s)wfp;ab tbulb 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.    $^{\circ} C$