What happens to the work dontm: xlyf 6x.83qha rv+e when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between:-z m67g q1/pa fxd x0s5kfeol them? Are the temperature changeloxm:x/1f 0 pz7aq6fg-k5sd e s of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will u-;,u0dl:fuc kj(jhp heat naturally flow from the object with higher internal energy to the object with lower internal energy;k0upuhf(-j:lujd c , ? (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 mjyz, zc6tm,3 the temperature may drop below freezing a few times in the m ,y6z c,mzjt3winter, 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 large. Expla2i 3(n( ezcm qfqt.r6nin why this fact makes water particularly good for heating systems (that is, hot-water radiators2(qr.n z 6tq n3cfeim().

Why does water in a metal cantee20fea l .ot-s(k:sk0-xgv fcqn stay cooler if the cloth jacket surrounding the canteen i(ffks: 0v e ql. 0-so2-actxgks kept moist?

Explain why burns caused by steam on the skin s k6 etwillw15-3 ifa*(kbf (zare often more severe than burns caused f*1w i(5tkifz3 l kwsla b-6e(by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates,-y utwc1.sf6gc ,mna4sr7yyuzan4 6; using the concepts of latent yag 6c1y.sn;f-4 ,w7m 6rzscauuynt4heat and internal energy.

Will potatoes cook faster if the water is boiling fasterad7 kgn3kvx3lx52 x2o?

Does an ordinary electric fan cool the agi te.8)rxx8yp f+d1ld 3en n-ir? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature ca y+rc3lyi(i de85r,xqn be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by coveringe f1rkuba*k a.w7xu35 themselves with snow erkw.3 bf*7uk uxa51a. Why would they do that?

Why is wet sand at the beach cooler to walk on than dry sa*9dwbse 1zn. dk xsgg. e-m*b.nd?

If you hear that an object has “high heat conciw5az n1+ g(mtent,” does that mean that its temperature i (m5aw+ngizc 1s high? Explain.

When hot-air furnaces are used to heat a house, why is it important that there bb,cn+2 z+ *aeiro+kbxe a vent for air to retur+ker2* zi x cb+o+anb,n to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometime 6meme( / ;,x;ondrl75gvisyss 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 wx,dsm lm6 y;gv;n5 / oris7e(einter?

Down sleeping bags and parkas are often specified as so many inches or c7;p sz4 hrryy,cj w39bentimeters cyjb4hr;9wys3pz r ,7of loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sd f *ghc2oq0e/ink” glued on top that looks like a series of fins. Why is it shaped like / qefoh* g0d2cthat?

Sea breezes are often encountered on sunny days at the shore*/a9 tod9y z* wcbwc;z of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of thc9dyzb9;z*/* oc w awte nearby water.

The floor of a house o ufuu07trz ltrq-fjg4x(,)(rn a foundation under which the air can flow is often cooler than a floor that rests directly on the gjxt7lr f ),zu4ur-q(rfu(0 tground (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 readingsf 2hng6r4(n qh2 acm (eft)l5 8 mux7)eqt)aps are always taken with the thermometer in th s5nfmgelqf)6em rh(x7h (c p22anqu)8t)at4 e shade.

A premature baby in an incubator can be dangerously cooled even when the aqmf5ep4o 5)p +vy 0unoir temperature+ppufe)mn 405oy5q vo in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it havt*:p(pqbvu-oghq . t 9: yhq2xe a vacuum between its two walls* xp:b.qgvqt pot( 2h- 9y:qhu?

Imagine you have a wall ib lsy:+(hiorr,uy-*that is very well insulated — it has a very high thermal resistanc*ior+i l-u :byy(r,s he, $R_1$ 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 aj l3yx, (p5jporound 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 ra3p5jlxjy p,o( diation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat w hku, 5e,uzkxx)1 0plthan a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up.,l pwxue ),k5zxukh0 1 Explain.

The Earth cools off aa)os eeuo3;q* t night much more quickly when the weather is clear than when cloudoe;oas)3e u *qy. Why?

An “emergency blanket” is au7+.3w1 u i4njljcsrp thin shiny (metal coated) plastic foil. Explain how it1uj .n7ju4pl iw+src3 can help to keep an immobile person warm.

Explain why cities situated by the ocean tend 9u ,xyccmnds +g.i*..bb wn,rto have less extreme temperatures than inc9nbx,mdc.nbs.,.g +*y irwuland cities at the same latitude.

  How much heat (in joules) is req)pesd(/3g- lfe vq 4csuired to raise the temperature of 30.0 kg of water from 15 vlee/d(q 4spf 3s )-cg$^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat rais0, g9fluycg* s*r s60ukaxg/y e 3.0 kg of water that is initially atlf r9uxa6s0gyc/*u ,yg0ks *g 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about gcgw 3u5exz3(vuypy)esc3xu a / t+; 32500 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 uni gu6:gaznyx/0 t of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lb of water byg /:60gauxz yn 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gz09 3pbtkuy3lbdn69hkb;:mv enerate $32,000\,kJ/h$ 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. Estimate how long it will take t 1i5yzg , o/m heg0h8.gxh7fgmo heat a cup of soup (assume this is 250 mL of water) gi0 .ehgh8mh/,f75x 1gzyogm from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the 4j2*(tens vsonz ,p+yz mq8: obrakes are used to bring a 1200-kg car to rest fzz s4ejoq 8y*mp+2n(vont:s,rom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 1 nlj6v17l3m.9mvbo zb 6 L of water. How much heat does it absorb if its temperatv73lob b9j.m nvm 61lzure rises from 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 needed 8anw1f, epy f4r6w)kdcwt8i: .piu6t to raise 5.1 kg of 8w udiir., p86p4w wc6naet1yff:k)t the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the samecwz )b (r(aj(q temperature rise when they absorb the same amount of heat. What is the)w rzbj q(c(a( ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometerfj) )ank8vwr7gwy70o 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 afc;y)l+qk+w n8) : czvpfow *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 (mass*ataz(aj/pv mln gbmcv7oc *f -;z 394 = $0.4\,kg$) 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 sub4gz7kbp p(6ok-,ou/e9 qqdsz stance 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 0.7x 5ly092za.wu 5 hvssl5 L of water initiallyhawl 5 2y5lzsux s.0v9 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 /-wlusi/; 5 ywax- )hkf ;jerhcandy from the following measurements. A 15-g sample ok xse ;l w5/h)-/fh-;yari jwuf 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 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-h; md(lcydfob 1k7lb *ms:1 x 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 has8gigqah3hn sf/ * ,up/ 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, of an object is define dnzdhi;:y v6s5a .)nrd as the amount of heat needed to rad;iz sd5a r6nyn) vh.:ise its temperature 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 melsjv2x 8 ++3goanj/ylpt 16.50 kg of silver 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-high building. i eqjvn m0q(ci3t0a f0(/t*j lIf 65% of the thermal eniqc j(0 03 ajfvnqt0m* /lti(eergy produced when it hits the ground 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 evapoepcd8i1fjb 8bj.5fnw , is*h)ration of water from the skin. How much water has been lost? pf cbb n1,h8 )se8*ifjwijd 5.   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 potc/ ,vy8mhgmogy(i8 4int is dropped into an insulated container of liquid nitrogen. How t h(v8yc4 yi 8gmgo/m,much nitrogen evaporates 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 tak8c-f,6h1ixc. r qhrlu en 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 contain*.ces v4l9yvs s 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 water over t .mls0)pv+.3h td8ry)q yfo ethe 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 effqtosh p 3+meyr0y). tdv.l8 f)iciency 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 a n9 npdv88;azyt 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 md5zel jihi9b 7)bxt ik;,xr )0ercury 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 ax s3+lz6vp9dbt $250\,m/s$ 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 *gmz01gq8lq r; wjxu 0 -xxcn-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 investigator notes that the 8.2-g lu /,3uxbc bmi,ead bullet that wa,u/,i 3b cxmbus stopped 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 aluminum rod with a diameterqb7c 0vsbe6m96zhwhm l ,n54s 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, assumin *z+(e uuti uhw1v qk4/+us znnh-de54g that there are strong gusty winds and the external tempe(4-nz/41 5keu*hqvn+dzuwhu+t e us irature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungs0yr*iw x9 -*m d:h.bds)wa uhjten sphere (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 /tcluju:jp*6ij1 i1* cfgve+bk , rp6200 W of heat flows by conduction from the blood capillaries beneath the skin to the body’s surfaceiicklbft6 puu/ c:1 r+ 6*j,pg1jj*ve 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-cm7lv.ds +vpc l(-thick brick wall. Because of a number of 100-W liv.l cvs+pl 7d(ghtbulbs 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 bg +3 (.d1 p1/n*at/vehkbqsjyk hq *bice 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 length and cross-sectional fss0)nbe ej**iod.7 y area are attached end to end (Fig. 1se0ief s*yb.7* dj)on 4–18). 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 constn:nlrtd ;ykl4e0os8v2 2slq *ant, estimate the rate at which the whole Earth receives ene*q nl 2ytor;4vl0d ks:8esl2n rgy 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 glastfjpnq 6b+ r+-s bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer su bn++ f6qt-rjprfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of t8 ; (3 tjy1bt dp6v0jmm:tuedrhe wall of a house come mainly from a 4.0-in. layer of brick and an R-19 mbrtdv(3e0yd8p t1j u:t 6;mjlayer 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 p mtw0 mhcgoi));6cc*v anes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flo i0v6c);*)omghctw c mw 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 should it take 1e ce3ejz+gj28 1.0 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 of liquid at 5 7k(bb0ug 86b3a zokwpvucy, .$^{\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 the worlsvl47 q2h1glj d’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approxima74l j2vqlsh1gte 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 o6lw7aof3 7tselhx2j,f wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermala7 l2hs6x 73tjof,e lw 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 x2yy4nm*2wtrz :eix+the Sun, assuming it to be a perfectrxx 2:iz +24ymw*etyn 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 may genert* zfrt)mlsqok 52r/: ate $200kcal/h$ 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 ok i. 6gi6h,/ua 7vxsjff a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remxk ig6./ 7vifu6a,s hjains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated; ,c3:8m mqpkv5ro mdo pail of water initially at 2m; k3,mq8ood :m5p crv0.0$^{\circ} C$. 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 a goose down jacket 3.5 cm thick with totawb4s:x ug 69eyt +0omil surface area 4xwy:oie+9 gb s6u0mt$1.2\,m^2$ 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 6pxs;7qw*dx/ uy in7l 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 heat can be conducted froqk 2 npo tofw;l5c35r.h :a-vxm the interior of the body to the surface. Assume that the thickness of tissue is 4.0r -xokv ha f:wqcl2.no5t5p;3 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 conductivity of afg u2k.7t jxgq6vy* o)ir) and )f kyv6gxg7 t2 o.jqu*area $410\,m^2$ 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 travde, )xua6* i0l1j iuqneling at $220\,m/s$ 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 part7kpa n ijmn.:1(gtl 8k (a) in Problem 58, take into account radiation from the leati1p7jannk m8: .gk(lf to calculate how much water must be transpired (evaporated) by the leaf 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 initif,2e)c xs1ay*z4jyme al temper1 e*)zjx fma cy2ys4,eature 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 with bzv ,2xyq7emmd)v61b in the Earth’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 -ceq1 csfiq3vy3 lza15*-n4 w p1tm emrubber ball at a wall until they are about to wm vqpqf3-a34 s1 m5i1 c-c1tzn*eyel drop due to dehydration 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 resul/ 3ro*rr2ya (y9 ujknlt 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 conduqnyb l b5t9u idd ;/0+1gfv0jhction and radiation at a rate of about 200 W. Estimate how long it would takebj t 0d/105bgn flyivd9huq; + 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 ho/tj+:2-qtx.te lc1qzl .jb i xt water” left in the 50-gal (185-L) water heaterjxjqxei 1l/ zt.t2lt:c +. q-b. 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-na. a(zldu5de46xv; c 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.    $^{\circ} C$