What happens to the work5-d5 veu uns )dl7y/mo:yusc, done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler 6sqe ih fln)w e: l42t*s9tpv(object, does temperature flow between them? Are the temperature c fi*st26 w vltn :l4e9hpe)s(qhanges of the two objects equal?

(a) If two objects of diffe dqk(p- oll+r*kw7 /)qxu6xs zrent temperatures are placed in contact, will heat naturally flow from the object with higher internal energy tod6)q-o kx/s( rzx kq*p+ll7wu the 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 temperwqkc ( 82yi(;c w,xeudz-h )xe va89qjature may drop below freezing a few tim)yaeiz8w9wv,j8hck c -(e 2xu( x;qqdes in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite :zeyw ea;k) :zjadf4i1b4x c, large. Explain why this fact makes water particularly good for heata)4:4,e; cjzba1xz :iw fdeyking systems (that is, hot-water radiators).

Why does water in a ,;iyj9dsihlz s2i)x / metal canteen stay cooler if the cloth jacket surrounding the canteeslx;i/i dzy i 9j)s2h,n is kept moist?

Explain why burns caused by steam on the skin are often lad5.jhky 33ppg :jc2xa2o3x -ic h9omore severe than burns caused by water 35jjxcx229:dl opycphg -oaa.3 k3ih at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, usioz qen7 kn*h4) +dgqzeq7u a+,ng the conc*dz ok47+g)eqne aqn,zuq+ h7 epts of latent heat and internal energy.

Will potatoes cook faster if the water is boiling z62 cfyb0xn c.3ye+;ge aw(fv faster?

Does an ordinary electric fan cool the air? Why or why not? If not, 7 a4f6vggzm1w, erskvpc cw1ngv8 ,z57*o,mjwhy use it?

Very high in the Earth’s atmosphere, the ps52vzxtwq;jv+(/ gp3 dc,g rtemperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Asmh4 99.s-39vx oo p8yuhnxyv rctic expeditions have survived by covering themselves with snow. Why wouldou-m yx.3hsvs h4nv yo98 x9p9 they do that?

Why is wet sand at the bllwhx bh6mc /x+mry/9s4/ 7piy a8aa) each cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mean that its tem(id7mkck9 c9v2c ybs0perature is high? Explainyc (9k2vdbm c9 7ck0si.

When hot-air furnaces are used to heat a house, why ishm my4e/2(av9 gd4d3;vw: cwws ilzl2 it important that there be a vent for air to return to the furnace? What happens if this vent is bloc 4/wv2gmy2wd3 e4l;h mav: sdlwiz9( cked by a bookcase?

Ceiling fans are sometimes re+tgqhbn*kg1 yxd.7 / nversible, so that they drive the air down in one season and pull it up in another season.b 1d/tg7.+* qxnhy gkn Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many i p g*rdm/z96cinches or centimeters of loft, the actual thickness of 6* gd rm/iczp9the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on 68 a)rolp8sy jmsum;5top that looks like a series of fins. Why is it syjps uoa5r;886mms )lhaped like that?

Sea breezes are often encountered on2 1 mbb6oxdmy71lxar1ox2 a1s xks4: u sunny days at the shore of a large body of water. Explain in light of the fact that the1m2 :sbo7bx1xx am o12d4l 6sx uy1rak temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow is ofte3 o2akv+r;)gpw6h nw dn cooler than a floor that rests directly on the ground (s) ;ndvo63 wp+grkh w2auch as a concrete slab foundation). 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 in thu)izo7mi*x x1xp( 3jw e shade.ii 3w*j o)71m pxuz(xx

A premature baby in an incubator can be dangearh05cy.7u52i.nyetz nm ,cyrously cooled even when the air tempz0t y ca 25myiye5c7.u.n hn,rerature in the incubator is warm. Explain.

Why is the liner of a thermos bottle silveredb44;z mc:sp sbun1s,n* emy2y (Fig. 14–15), and why does it have a vacuum between itse s1 y:44nn,p cu;zb*s s2mbmy two walls?

Imagine you have a wall that is very well insulated — it hat9g .vm3y:f 8h)pziwx9 3qa dus a very high thermal 9g3wqp hd f)i:8xy3a.z9tmv u resistance, $R_1$ 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 processes: (1) ventilation zwuuuhe**d, :mr,t 0k3p ksj0around 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:s rmw0**k ukt j,p 3udz,uh0e) 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 md8 qy1m+ a lh)9xryc-pore heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Explainrl8y1 )h 9mcy xp+-adq.

The Earth cools off at night mu h;e/gtbsv /-1xsm;gqch more quickly when the weather is clear than when clouhvs-g1q ; //;bxges tmdy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic fw qds(*z .m(vtoil. Explain how it caz.t dw(sm v*q(n help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less ex kmw 5sa mfnyk7*gq4-.treme temperatures than inland cities5k4kf-7.*qa mw gmys n at the same latitude.

  How much heat (in joules) i /e d3izh0akqt :+ ta48yt:txis required to raise the temperature of 30.0 kg of water fryz at8a:/xt0+ :i dket4qh3it om 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heatmfn pxwoe)*fg :6-dd) raise 3.0 kg of water that is initially at 10.g*6p-:mxw dofd ) )efn0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person c3jbznutj12 qx 0x/p+sonsumes about 2500 Cal 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 system; bneu p1 ;0vcms1vm6v of units. One Btu is defined as the heat needed t1ev;6ups1 0cmmvn ;vbo raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate q6ey* d mqh3up 272wwg$32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is/bl4gj rkueuf4uh12t. onrb . u5e:geus /7a; rated at 350 W. Estimate how long it will take to heat a cup of soup (assumu45 17ksulbn2f; j/ugeb uhre ga .uo4r.t/e:e this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories ar,r- 6w)drszvb e generated when the brakes are used to bring a 1200-kg car to rest from a speed o wzrv,)r6-sbd f $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of w1r,fqgj a .a;pr3gbpr6mi 01r ater. How much heat does it absorb if i igp rrmg; 6,rqabfaj10 .13rpts temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific hearx3 rq+n( ktfvd4v,);ytr i2at of a metal substance if 135 kJ of heat is needed to raise 5.1 kg of the fxrrvq;yakd4,r(n )2t3t+ vimetal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and watcz1mt*q u z)( l7zr 5ic*l9ixter experience the same temperature rise when they absorb the same amount of heat. What trql(c i zxc59 71zzim*tu)*lis the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomugyd(nzv -fv97s/1j z eter reads 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 equilibrium temperature when a 245-g block of copp5m1/u il(2 jhqxrjv 3ser 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.j-8,ww1 xwpn4vgnzs (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 is heated to0q ;d xonb qkj6y+a/7va,y)u g 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 coffeepocfnb)40l x wa;+ twka2t to bring to a boil 0.75 L of water initially atwc+;akbfw0)xa2 4 tln 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 following measurx bp 0a8czrh-o)u (8ovements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a h0bxvz )8uaoo- pr(8 cmass 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 of iron at 180k4x u z6,p4f/tk en6sxv1nq*e$^{\circ} C$ 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 hasy4vd3xp2/ 4 wdl 1ctoi a speed 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, ox25p r4cb m)mef an object is defined as the amount of heat needed to raise its temperature pxr4e cmbm)25 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.gs)9bb gho9e 550 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphg3zyc14 +x oe3lpshmwk::h i9ere is dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperaturp:lx+ 3 9yeh3hiw4 zgs1ok:mce increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat inv k bw(-rtld+)a*gppt/6i :wz /g0qrn 30 min by evaporation of water from the skin. How much water vbg-0rd/ i )k*:+tglp/wt( z6q rwpnahas 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 m ys**zmxag9z9,d rne t.saw+)elting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evapow astszr*y9mez*x) na,+g d9. rates if it is at its boiling point of 77 K and 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 tak rxd7));z yvycen 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 maszt8v8 djjtx6;x7-q*9)tdsd( jrs urws 230 kg contains 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 consumes 8.0 L of wat/cos0thejkq. ; c9y9qy +rxx k.zo4 t-er 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 t ;+qts.h.jo yck90-xrxcz /kyto 9e4qhe 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 )htfz1q3t t 3u(or-ar100$^{\circ} C$ 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 mercutky7p2 6rbqc ;a1pfo+kj 29nkry 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 travels; zmww2zsja5 5/kj9x:ycd6bing 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 mov9ub9 d.swl 6ukn7 cxj4ing 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 the 8.2-g lead bullqgpk13f;e wq ,et that was stoppek3qq wpf,g;1 ed in a doorframe 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 al 9bqzovq a 3b0tih88c6/+zotauminum rod with a diameter of 2.0 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 in Example 14–10, assuming that 120q m-yjfnufipg9rpvj) 4s;*v 9hfw there are strong gusty winds and the external temperatuyff-jf;sr2 019vp 9* q nmwhjgpu)4vire is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (e0moe4qnkk df2lub 903missivity $e\,=\,0.35$) 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 condu7 t7h wr;t:jceel2g+shzou4( ction from the blood capillaries beneath the skin :ehgtz 2 j hue l;o+(rcts77w4to 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 side, share a 12 gc9: f d1sj+-s3vjtid-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the+ 1jid9js:stdvc g-3 f 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 2 h)(1b c1momfg.( uq p44vfgjk*tugnblock 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 z9 6wl/ 2)c jxv/jg b2suslj*sthe same length and cross-sectional area are att vxsgjjl/cj b/*u 2)zs6l92wsached end to end (Fig. 14–18). The copper end is placed in a furnace maintained 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 whoh-*we hso,v i6d48s dyle Earth receives energy from the -68 sdhv4 ,eds yi*whoSun.    $ \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 bp67 8 +muq4(pjjsr/e8ph(b1qlxs (gxhjo 9m 95 W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.08+poum msbjl 69g b7/px8xhj41 (sj(re(qphq mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qurs) 7kb1n/ci, amg mz6alities of the wall of a house come mainly from a 4.0-in. layer of bricb kc sgami/1z r7)6,nmk 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 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 sp.0scbr f7;yh1 ax-lmiace, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction i. fx 10i ys7mhblacr;-s 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 x1mz /hhkf36 zhijo2r*z . bc7should 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 kg bquns n,r 3p(3( nl0fy:wrwr1 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 is contained xym.*oh*e +mk in the world’s oceans, estimate the 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 .ymmeh**x +ko for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing iz*hr*pe qzo0 ,t into a fixed block of wood with a mass of r *qzh,o e*0zp1.05 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 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assumingc3xgho i5u+ m:agrny-bed/00+- zdft it to be a perfect emitter +aec+5omrz d- /g-ing: h 3t0xufybd0at $T\,=\,5500K$ 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, z 3(q;l/2gx v *jxfgpfa 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 o du7 g3b,8d3sdk ub7tcf a cliff and falls a vertical height of 140 m before st bd ubs3d,8gd77uk3c triking 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 2y)tu: 7x(tq-g:k (:hefp4f 1kl lhb kw.5-L insulated pail of water initially at 20.0q fb7: p-k4 l1k w gylf:htxu(t(hke:)$^{\circ} C$. 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 d1l2 pihghi2s:xc.klt 9dg :; cj6jn/pown jacket 3.5 cm thick with total surface areagij1hk;n:/ : cpjt lil2px.6dhg s29c $1.2\,m^2$ 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 average2k /v (matnfvr+;2cub metabolism 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 gd5g-ke pi0yqw 5k y,7-nhbp2 heat can be conducted from the interior of the body to the surface. Assume that the thicknessik-ghp k2gw - 50y5qbnye p,d7 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 17.3/w egoe g6kp/5 cm thick (assume conductivity of air) and a/w6e3pkog/eg rea $410\,m^2$ 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 l(x,7lch.fmf$220\,m/s$ 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 Probl-si+*uv,w yvbn ok ,s2em 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the , nvv2buo- ,i*sk+ swyleaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its 9e4c 6q7*vq) sk iqohrq4op/zinitial temperat4 ropqezvi7h 9q)sc q*6kq/o4 ure 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 Eare ui o(eyoo/*1uom73v0, qpjwth’s crust increases 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 m/ gm,tkr-ck:rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity ofg,k/rtm- cm :k $22\,m/s$ 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 wh dql5* bxl3+g h.wf2wq4z dew5en 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 radiatz x43lro,p0u mion at a rate of about 24p 0z l3,murox00 W. Estimate how long it would take 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 dishwashing, there is “no hot water” left ifkqamu,:2x 6e+t +n kln the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at roughlyka2,+l e:qtumk6f+ nx 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 * s:n(w;iycivro xs3 9u4qme/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.    $^{\circ} C$