What happens to the work done when9wza vpj1eu+f :d3+ fi a jar of orange juice is vigorously shaken?

When a hot object warms a cooler objec8gbi ykv,t 6omyjnov7-/xn 50 t, does temperature flow between them? Are the temperature changes of the two objects equalnj0 k7i vny/o,mgob-yxv86t 5?

(a) If two objects of u402 2ojcyh1 bkrj(acdifferent temperatures are placed in contact, will heat naturally flow from the object with higher0k1hayc2rjj (2ub c o4 internal energy to 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 buxr2n,bl4 qmv z(ssp014a mwc5 t the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by wateri (p5b1lv s2m4zsm xqn,cw 04arng them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water lj ;.q9 mb9m pq;+pgaacsvh429s: sczparticularly good for heatinsabm9l;p.:qmvqc + sjg; 9sa 9hz2 4pcg systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surrounding 165o el14sxo t l:mv lk0ykf*fthe cant y1eftk0 :64k*o1vfs lxl5m oleen is kept moist?

Explain why burns caused by steam on the skin are48byppa i isw:9p/z, s4 gy:glwochk*6e1: jg often more severe than burns caused by *pg9 , 4h1w6 :iwzp8 kj4plsieoysgag:c /b y:water at 100 $^{\circ} C$ .

Explain why water cools (its temperatu d/ -lbp6ba/eere drops) when it evaporates, using the concepts of latent hed b6eael b-/p/at and internal energy.

Will potatoes cook faster if the water io*aaoiz:;ka( /ea zf0s boiling faster?

Does an ordinary electric fan cool the air? m7afngzo5r6 / Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temper79/w fi)hhz)w4s lfmbature 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 themselves with*mz efe;p nzk 06;oz9ofw47cs snow* zfc 769ns;emeo;z pofkw4z0. Why would they do that?

Why is wet sand at the bl ju3 e c3-kp4h/utfaa :vl2y,each cooler to walk on than dry sand?

If you hear that an o8nb/s7a vuhlml xj-4kw a(+a9bject has “high heat content,” does that mean that its temperatu janlmw7s-4+/kaubv a8(l 9hxre is high? Explain.

When hot-air furnaces are used to heat a house, why is it important that t+f h*aepa4z+lbs c.b-here be a vent for air to retu s p+f +e4-a*la.bbhzcrn to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the ai4vhx)w)wdy3 k r down in one sea)d3vw wy)4khx son and pull it up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches qm5w ;,4n q(nucoc: ocor centimeters ofucn, ;:( 5nw4cmooqcq loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top8 iuq7 e uiii2jew95e*xg*ei : jn1,zg that looks like a series of :7ii*j, gwezx*i ii1 5n8ueu gje9q2e fins. Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large body ()1gamh(psb0/ zowav of water. Explain in light of the fact o/bagv(( )amzp 0hs1wthat the 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 often coi q* a3v 6cng5g.2xzvkoler thag zv ga.6iv cq2*5nkx3n a floor that rests directly on the ground (such 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 tigljk6w 90g )vhermometer in the svg gw9 60ilj)khade.

A premature baby in an incub:4gaon 5erlgvv: y *ky)s5 nr(ator can be dangerously cooled even when the air temperature in the incubator is warm. Explaiaysr5kv(o e5nvl*4 : g)gn r:yn.

Why is the liner of a thermos bottle silvered (Fig. 14–+xy j9aq da4(q8f ,p.u t2cvqiur4;q-u(vwzq15), and why does it have a fa, iq 8a2yqru4wd uz(j4 xc.+ (- vtq9quvp;qvacuum between its two walls?

Imagine you have a wall that is very well ikr(c 7wy3jahh4ve a1k ;0,jcoz(uw+q nsulated — it has a very high thermal resistance, a+crhkj o4w;j1wc0(aekh 7(v 3uzqy ,$R_1$ 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 followi4uqol(+q+zl.b1s 6twk ( cyggng processes: (1) ventilation around edges; (2) thokcbztql(lg.+1y 4 u(g6sq+w rough 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 radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny mrh 3vmi8u2.:8 .h6vhax n jsajetal. Yet the wood feels le2.h8v8 hu3sr mj:.6 iajnhxavss hot than the metal when you pick it up. Explain.

The Earth cools off at nighdm3. ;gkioht+ t much more quickly when the weather is clear than when cloudy. Wh m;k o.ht+d3igy?

An “emergency blanket” is a thin shiny (metal coated) plastic foil c9hk/9bl z3t;zxra40p2woiz . Explain how it can hexiz3kb0z;/ 9a h9z4to cp lrw2lp to keep an immobile person warm.

Explain why cities situated by the om q /10au*/lmuyqlpp +. yv hnho1ds27cean tend to have less extreme temperatures than inland cities at thmlu2 1*1/m7/h.h qvapnyu o +lpdsyq0 e same latitude.

  How much heat (in joules) is required to rfdj98e+zjl -9e /fipoi1 jlt1aise the temperature of 30.0 kg of water from1f djli8p+/t9oj 9ijf1l ee-z 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 is initially /rm+cqdgxicy,7c51td 1 r gh5at 1 xdy/c,i 1r+g5d q1c7rhgt cm50.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person con -mpi-hh*,,arba*2 l oljyb7e ox i9f+sumes 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 systt3hro;n( s6q3t v zr/r pu:3hdem of units. One Btu is defined3hvtzq(d rprt36 rsho: ;u3n / as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate6 cqhek/9 agi+ $32,000\,kJ/h$ 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 35/pb 6/y5mcmzpx u7w) c0 W. Estimate how long it will take to heat a cup of soup (assume this is xc6/c7 uwz/m5pmby) p250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bringz:gv pois81 ch496xxzec/ i;f a 1200-kg car xii;4c:9eho p8cvzgx16f/zsto rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heatgh9z0:h;tck d :l*ch p does it absorb if its temperaturkhzg;0c 9:tc*dhlp: he rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat 071s wmtg3uln of a metal substance if 135 kJ of heat is needed to raise 5.1 01nt3u ls7w gmkg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and wates+;jk+:-tci . o /t(lg o tzjx8x8nnpar experience the same temperature rise when they absorb the same amount of heat. What is the rat l8(i:j++n /p tag;xs -jx.tc tnzook8io of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21.k5ugv )r0bm-b 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 blo 07 b/pu.tzm)/d iirseck 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 horseshoeyww i * xwlo8(9nuu+r5 (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 he v8fg1y7mr:eyated 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 boilstoo rs(;2cb , 0.75 L of water initiallob;ro,2 ssc(ty 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 followin+7uwrni4r 3u/ j *tlngg 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 calorimete +rjil 37wt u*g4urnn/r 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 l r*-,n uq6oslat 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,n*3 3 q(o dy2jwhcdts 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, of1p1dzzrb 8.op et u1m,e *l9zso.3xlq an object is defined as the amount of heat needed to raise its temperature b1eu18ro3b * ez,x 9oqtpll.1sdm zz.py 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 sidwx2pt 3a+ -aly kn;y8lver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roo9slmcp;+abpg h/7/c +ipm * ydf of a 45-m-high building. If 65% of the thermal energy produced when it hits the g g dyhm9+7m * pb/sp;c+pca/ilround 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+l h;qk *hsn2h evaporation of water from the skin. How +hh2n; qhk* lsmuch 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 gfqq0q1ma 2a,t5dq.f)e:.8fk bix an dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is e1:f 2tq0f5q .d qiq8.xma) aaf,b nkgat 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 takesq ):v)ss :gbyn 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 830(z x3nd5bp) fu,hh9i f 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 water over the span of four hdse 4:vdrxj b o-/fp/qdw29,zm/q0dj ours. 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 ab0mjw/ qdzdo qv e -p9dj/b2fsdx:/ r4,out 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam atox(7vv/su m- cuzhz8* 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 mercuryp -zg*(h5dyni 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 travelip 2du9e3sddrk;x z+n.pjg h1:ng 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-skaterrpsj2quwhifs 1z+h).6g( dq ) moving 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 investigatoa6atvnahig 7;04 z6w ir notes that the 8.2-g lead bullet that was stopped in a dooaiwz4tgn v 7;iaah06 6rframe 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 +3p0na6vv xl sis 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 Exampr0h/vk4 5s;sk8a;weo c 8mp2 ijegaj0le 14–10, assuming that there are 0r ; aioe 5ask8jme/s2 gw;kh840jvpc strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivitc hju)l.ot nlwzc;*)-ni 07pyy $e\,=\,0.35$) 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 yu; gg)c gu522p x0c8+uobh2gzpyk -q flows by conduction from the blood capillaries b 5gxyp)o0 ucukpgyz-+h 2g qcg u2;82beneath 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 side, share a 12-cm-thick brick5zl yz: tn). aos9e+ub wall. Because of5y. s+z)unob:el az9t a number of 100-W lightbulbs in one room, 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 i v8anp 9x s7)ira:p gda5oh0t44 o:89krztnmnce 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 57n7ro8 q hotvthe same length and cross-sectional area are attached end to end (Fig. 1 noho7v5rtq 874–18). 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 a6,.0 ml tncd5 wdc/vxnt which the whole Earth receives energy from the Sun. tn /ld5 vwc ,x0c.mdn6   $ \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, whic - ctyiij,r xqfpk0x1;e5s09l/gvu-ah is dissipated through a glass bulb thais 0q;j a-telfgvc/yr kxi5,x-9up 01 t has a radius 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 wall of a house come mainly from a 4.0-ii9n1a (ladna 3n. layer of brick and an R-19 layer ofan9 l1 ida3n(a 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 t,d 4oy*-q vaar4c7 yqpx j:aa6wo panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window byp,*y 6 xoyaa c:dr 4aq7jvq4a- 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 kg of ici*9,p +bvfw unu0;hxz e 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 lbx1 g8tri4 *am l54*ut (;;p nvtuylpriquid 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 t am)fuf g7mky3uk)14vhermal energy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by )yag)fm3uf 1 muk4k7v 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 block of wyh+(.w gj8 3xe:sk aiqood 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 0.:ksea(q xjhwg +.83 iy020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total powedggst(. ++c lxr radiated into space by the Sun, assuming it to be a perfect etx( ld++g.csgmitter 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 may generatekjrc6 : 8ruh*tp:kwkunm71 9 c*ea7lz $200kcal/h$ 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 ve e k*5,qgp *rqy- cc 3hat7bo07nw,akyrtical height of 140 m before striking the ground. Estimate the temperature rise of tq bao 5*q pg*w 0rany,yh7c,tkc7e3k- he 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-qcxwre4 k3,+ sL insulated pail of water initially at 20.0 +qcr e,skx34w$^{\circ} C$. 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 r*r2hnm sid-t+8kg 2-n/ q hsvgoose down jacket 3.5 cm thick with total surface are tksdn-2hn+2ir8-mrhq *g vs/a $1.2\,m^2$ 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 metabolisxof-o3u) , wft,p az.bm 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 conducted from the interior of t c1:: dmze yobpj79dv+he body to the s9p::v7bmc zyed o1jd+ urface. 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 thick (assume co m1)v9lj7wby0rw76mf 5mvg lh .hiux :nductivity of air) and area vi xm uvwj9l16 hlm7rb7wy.5m h: fg0)$410\,m^2$ 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 azc hn6oxrrn2:0 6g .xrt $220\,m/s$ 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, take into account radia3v5g eh5y5xc5i3q/xu8a jn cition from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a tempera hc5vxcxn353 j yeuia5q8g/i5 ture of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its ijsy0iz,y 66ny7ns2 y agumm8*nitial temperature msy,n2u y y6y8m6ijg na0*7zswas -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 increa hp)+u24wq xzymxw42sses 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), two5qwy* +li(ys 0gf-fl m people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the +lwm(l q0ysyffi-5* g 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 result when equanbqn;/7*h v gabxc9,xl 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 andhu-eq8g za6+9wt7s-docbh4 m 6kuqo8 radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop from 36.6wd-s+hem 7 oho 9bctak8-466q gzuq8 u$^{\circ} C$ 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 hotgji(durjzgs rm k2b n :homc)+* s*93. water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied anir).3zdg 9 cjsb+ n(jr2hu:msmgo *k*d 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 /14lk y nin+pjj37ix.od w cy 0ta8x2z60-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.    $^{\circ} C$