What happens to the work dotd+ hqw zepby11: o) ;/odjq;ine when a jar of orange juice is vigorously shaken?

When a hot object warms a cob0+7j bdfrp28fq;s xlm yoj: *oler object, does temperature flow between them? Are the temperature changes of the two+s7yo2j m: dxfjbq8;r* lfbp0 objects equal?

(a) If two objects of difw1+2qpwp: 4e.ny0 ylp kb zh77hm- ymrferent temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower inhy mw4zrpwep7h7n m:2p0qly 1.k-by+ ternal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperature may h rh7i0qo y3g*drop below freezing a fewirqhh *yo 037g times 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 large. Explain why this fact makes6goefo 3ya tkt+*55o i water particularly good o55go36* aef+ttikoy for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sgz zo( r k47bled-- pd8jt5jv)urrounding the canteegjdvt -klzo8pb4rj)e 5( d7z -n is kept moist?

Explain why burns caused:j *3s eg6;nr2d ,ez;.sh wjgf,w m2dy)gjttx by steam on the skin are often more severe than burns ca* m2)sx6 ytghesdtdgwg,3j2r:f ,w;n;e.zj jused by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporaek 8))b fmb5fg8rccp /+h d.jbtes, using the concepts of latec c8d8b.mh))/bpbj +e5fr fkgnt heat and internal energy.

Will potatoes cook faster if the water isa(;(v nhhgg,-uaj6nd h wj.s2 boiling faster?

Does an ordinary electric fan co8(of, i*jg gbcol the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can4g6rqixb( ol)e (7 ufl be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic emgj7.3uuc2:qmm fpl5- wb7 p rxpeditions have survived by covering themselves with snowrwu f:m5c-p7qpm7jb 2u 3.mlg . Why would they do that?

Why is wet sand at the beach cooler to walk on than dryi22 +yoa.kr2v);0b,tfog1uhfvg f r l sand?

If you hear that an object has “high heat content,” does tzk+( xvq qrnmw0+zq,g2 qlo* jco71-c hat mean that its temperature is highqq2*,ro 7 l0zzj+mc+ 1xgn-qvcwk(o q ? Explain.

When hot-air furnaces are used to heat a house, why is it important that xqfmi u. gay,m:0f2 2gthere be a vent for air to return to t u0m.f2ggmya2 qixf:,he furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the+ 0uy w-waexzwe*t8sg9+t)v k air down in one season and pull it up in another season. Which way should you set the fan for summer? For wiazw0+t* -t+seg wu89 wyxkv)enter?

Down sleeping bags and parkas are often specified as so many inches or centii kk y),xh/cc(meters of loft, the actual thickness of the garment when it is fluffed up. Explai, kxkyi()c ch/n.

Microprocessor chips have a “hpmua6hbk9(t-*b kk*k/exc 9feat sink” glued on top that looks like a series of fins. Wh-9axkup(6ktk k fmbh* 9/cb e*y is it shaped like that?

Sea breezes are often encountered on sunny davlv7r ;6elp: fys at the shore of a large body of water. Explain in light of the fact that t6 ll :evrp;v7fhe 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 oftfm5h xhi9v u.yj+wl.,3 i)2q)nwma rwen cooler than a floor that rests directly oql.mn.wywr5 ) + ,h2aiui3mh wjx 9)vfn 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 alm;m05m8e7ga07iord*h5 dks0 sqvyqp ways taken with the thermometer in the shadere5 omqkvs00g7s m0pdy*5;7q8dhi a m.

A premature baby in an incubator can be dangerously cooled eo ja999:f:k:e8iu +b(mz7u pdn notlaven when the air tempe k:8 pi:bd:9 ouu at7jo+ fane9m(9lznrature in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), arxkj+xvw*0q v (+myr. ld6 ts5nd why does it have a vaculdvxw mv r+ xq0j+ys6 *.(5rktum between its two walls?

Imagine you have a wall tha;a.ug(i xlwj.t is very well insulated — it has a very high thermal wj( u la;gx..iresistance, $R_1$ 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 processesmq59b6 ,-usk . *6ktcdqw/nkb j7lotv : (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) 9k,7.-nbw* jtlqd mv5bo kt/6kq 6 csuFor 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 piecefe*w 5lc8 sl9lmxu4-o of shiny metal. Yet the wood feels less hot than the metal when yel5m84lw9lu- fso xc* ou pick it up. Explain.

The Earth cools off at night much more quickly when the weather is cle (epbadjw+h3 9ar than when bpw(je 39ah +dcloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Expek9 rdb.8w dg :2n1o:nt5j ;sfm:llmmlain how it can help to keep an immobn b91mnoektdllm5 wj.;df28: s r:m: gile person warm.

Explain why cities sig3nv* 0vuf ra*pjae7 ,eh2hr/tuated by the ocean tend to have less extreme temperatures than inland citigae rnh/uf,** e23r7jv0vha pes at the same latitude.

  How much heat (in joules) is required to raise the xgnue/3u3*w b0mce:x/ vi qt5-xh i7otemperature of 30.0 kg of water from 1vo tmb g-3ci/hwqux3n :/eiue*5xx075 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heaz,/8q.xke nyzzkbzqf;*r(z1 t raise 3.0 kg of water that is initially at 10.0bzkr(xnef,8z./zz1zk ;y qq* $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about9mlr9 exbs ybsh*3 jc10c + +d(od.pmi 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 ub,0 sgtbwy9 hsj*:ac.nit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lb of w. s9j:yhtscbw,0bg*aater by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gw89s m6m j+vvmenerate $32,000\,kJ/h$ 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 31 x8ydynd6gd9 i +kio350 W. Estimate how long it will take to heatk y81+dn9ig36iod yx d a cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bring a 1, 3vtjogxdifhw 81 70k200-kg car to 1oxt 0 jv3,hw i8kgf7drest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much hea +is5tp80vvox on+; byt does it absorb ifv508s +px+vnbi ; tooy its temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ obw do-l1j):2xfh;m syq k6pa 6f heat is needed to raise 5.1 kg h xjqw)a:-6p2b m6;1okdsyl f of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience tvi2 lqhanbd 9 .;s02y,d limr01w 8irwhe same temperature rise when they absorb the i00l22h.nq svby 9rl iw;di, w 1rda8msame amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer re5vb7s :dear 3q2 vtus/ads 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-rt/rfk82: shs nm*tjk5wut f3(; uzh*g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (mass =pw;(l tym.,jcr3x*za /8q a w knmb6e+ $0.4\,kg$) 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 6q )mczwv:58qw xxj ehbp.1;qis heated to 330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffeepot to bring to a boil 0.75 L of water dhn87wfz- z8 oh7vt)l initially at 8.0hhf77vzd8w-8)n tzo l$^{\circ}C$? 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 measureme./r:m2:nc ji);pe8mztom hx g7;jof ents. A 15-g samm mngfjmji;ox7c/2p ;:et. r e8oh :z)ple of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 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 18s,w keb 2.h: 1hjhey-l8 e6h/fhqp uj,0$^{\circ} C$ 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 hamd9hzdi/60r+n5 l mg ldmer has 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 sdmrrlrk-cbj r n4k,.:sm f8z(j. ; i;defined as the amount of heat needed to ra-4:.;n;jc rmsz k8,klbid r.sfr r(jmise 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 melt 16.50 kg of silver that is initi /jb7mvu)5h tddjn22 vally at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the rooj +;bs1; kl s/oaqn m:fl7o;oirm4t .bf of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by ther; 4t;bs +iooa;/qnkf.sl mbjlo m7 :1 sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 1/p dsocp) 9+yy80 kcal of heat in 30 min by evaporation of water from the skin. How much9)y+pspy/ doc water has been lost?    kg

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

  A 30-g ice cube at its melting point is dropped into an insula0 3iglvr 7rz+;cia ne-ted container of liquid nitrogen. How much nitrogen evaporates if it is at its boilingn3rgrz-0ei +av; li7 c 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 taken from the zw lv4 t8zkit2,ts04; dam0mcfreezer 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 6m .hl8+lp znvkg 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 bicyc i6yt:i 8pi z0clrkwkxw+7z: :list consumes 8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumedcr 0ki i8x+z :lwtky i7:w6zp: does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 10 ed qy-9hy1 1f/vat.cyc8n 3tq0$^{\circ} C$ 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 mercury::oqk g*vs;9 vvjreg1 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 travelrt z i mppxia24g)6.2ping 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 movmj)1 x2w s13hwsbw 7ym d9w3iwing 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 i.cuu-s8 .nde nnvestigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted complete.-sun8eu c.d nly 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 diameterhznqs(2gz k9( 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 by7xz ;+x2r3ss)pht 1aa (0 gpek(hw evk6glq7h conduction in Example 14–10, assuming that there are strong gusty windh)e(2tewq3pkl+s6hr;vx0za 7(g ks 1h pa x7g s and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (wu u: ;.upjh7z8y u;jremissivity $e\,=\,0.35$) 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 conduction from the blbu3a*z 5uc-v4bz1qk i fbq +y;:gmas1ood capillaries benz+-vz3csa q a 5bkbq:yif1uu;14mb *geath 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 brick wall. Becausege+w5 th8i2mxdx. - p1ft.mrz of a number of 100-W lightbulbs in one room, the air is xt51 m8pr+z f2 ex.-dhtwm ig.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 bn x mq v4.e*y4qdyk;-7+lpfhw7 dn, xmelt 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 lengthdk+ )a cfhv,i4d6zq 5h6l zy*k and cross-sectional area are attach6kvz akc), d +6l4zf*ihhq y5ded 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 whole Earth zoduy(w5llmx.wd-t 1l3nk ;:receives energy from tl u:lw o3yt mz;-5nwl.x1kd (dhe 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 ikz xti5yh*4.z * r5uhis dissipated through a glass bulb that haszhxu4r z** 5ii.kyht5 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 hocrna2fj(.0z; s(cyb quse come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of hebq(yc f2 z;j0s n(cra.at 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 airb-;hm7zju+ qv space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction is given byvm+ 7 -hbujqz;
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
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 kvcry29 (+xlsvih o2f/ g 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.hnw(hv .x dd25ck4g;k20 kg 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 envyj84*m ( q:fidm3 sy.qa:jukergy 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 1 K. (Approximate the ocean water as pure wa(8q:.: myfqkju jay d* si3vm4ter for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood withs4s6boqpr: d /c rj9em v0m2d* a mass of 1.05 kg. The block and imbedded bullet together ab6dej*rqm/ ms vdr9p0sb2co 4:sorb 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 Su 0a4dq 2 mqg6;utbckq5n, assuming it to be a perfect emia ukb0 5mq;qgq dct426tter 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 person1 hc1 +rpfl uejjbj52 e5w1-am 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 o6y. ik,jau7o 1ukz 1byaf p;8bf a cliff and falls a vertical height of 140 m before striking the ground. Estimb 1u af yyzu6,8k7 kapjob;1.iate 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 droppeaaiiy m kcb47*j1 5q+kd into a 2.5-L insulated pail of water initially at 20.4kcj7+* qi bky1i ama50$^{\circ} C$. 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 surface areb 6:k2aie p(d+rhb ddu;1 te-ca ek tead6b2: +;udbip1dc( -h r$1.2\,m^2$ 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 7)wsnlx2l k3)gi 4nmy average 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 from the interior of h e tfj0n4(r*xthe body to the 4nt(rj hefx*0 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 thick (assume conductivity of air) and-p: u(dypgb0:awt5y6 it o7bq areatpba 5y( 60 q i-gup7:t:ywodb $410\,m^2$ 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 tr4/lkgn uk,4sfx,pj l. aveling 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 part (a) in Problem 58,i1gda:fw jph: cm r5bsonf4 go(+336c take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain c6fw3jh p :(gf3o m:5+ bgnsadi1o cr4a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts 7vnzy/dbs46xwd) qb2(n4 v rl when it enters the Earth’s atmosphere. If its initial temperature was -125b ( nqvv 4 6s7nr)dyb2xd4/wzl$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s crust increases abouafc f3)k;vww.0d.bn0kzv i a; t 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*g(xs zp:dd4o bqxp- b mr(o07 at a wall until they are about to drop due to dehydration and exhaust-xsd0zp*p ob(7 :q m dgrbo(4xion. 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 result when equal u,la2mix s6pd:i5 qt(a jz15xmasses 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 r+c0t3u.5e u 4 alpilbdate of abo5b la3tceup0ui d 4.+lut 200 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, thecv(egvgp( k8g *.uxswu:p/a9re is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the ta/ kv.upewv(cg s:(apugg8x*9nk 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 ofv6zf hlc ,s,u9 a 60-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.    $^{\circ} C$