What happens to the work done when 8,)ttfey6* g ebqvg,2plzb -k a jar of orange juice is vigorously shaken?

When a hot object warms a cool hs (w,a9is8ym1;.prsoyfqd n3u + 4fyer object, does temperature flow between them? Are the temperature changes of the two ofmhi,s 3pyowd8y f9ur ysa n+.;q(1s4bjects equal?

(a) If two objects of different temperatures are placed in contact, willmswod.xsb5 6t;oepm5k 3 vd.m3tnn+) heat naturallydx)m3mvm56 .s s pb3wk tt5; neondo.+ flow from the object with higher 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 tropbpjlen h6 kosdcm i)a4 l,73:6d;uu y.5p n*ysical plants grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezic,mp l 3h56:* bonsuenjliydy6kus)a7p 4d.;ng can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water pdhp0m j4 8ue n0z/5c)hct9iyharticularly good for heating systemsmh4c tu9zye0cp /)0dh 5hnj8i (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroundingzi;w8ulg lm0a2nznz(q ;1 o:b the canteen is kept zoml20 :8qa ui(w1;b g nz;zlnmoist?

Explain why burns caused by steam on the skin are often more severe than burns ys (77ad q4kp;6nzdtsc(;7p6z7 ta4 sdqykdnsaused by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evapors,uc,op b 8(zcates, using the concepts of latent heat and internal bc,,( u o8czspenergy.

Will potatoes cook fast6)m t r8,xsjt2 gbps*yer if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If ;f22vc okt9g vnot, why use it?

Very high in the Earth’s atmosphere, the temperature cawdqnny9.7ee dr0 to3, nas)7n n be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by xv23(1d fvdv wcovering themselves with snow. Wh1f2v dx (vvdw3y would they do that?

Why is wet sand at theo4xi* gw bvx+6yqt7 t, td6-tk beach cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does l;enz2w jz43 k3nj(i gthat mean that its temperature is high? Explainlgew( k3;jjzn23i 4zn.

When hot-air furnaces are used to heat a house, why is it important that theruqheqlz3htjev) und7+-. 1w ;e be a vent for air to return to the furnace? What happens if this vent q+7je.zh ;3hwe)u1qvul -n td is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the airndru g gm.+ aos7s(8z+ down in one season and pull it up in another season. Which way should you se mua+rs g.zn7sd+o( g8t the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so dobm g xpn:z5 *)xa4o0many inches or centimeters of loft, the actual thickness of the garment when it is fluffed upbapoxzg05 4n*m ) xo:d. Explain.

Microprocessor chips have a “heat nkth:t::mp1ajjj2 wog4cn ,*sink” glued on top that looks like a series of fins. Why is it shaped likj4 j,o: tg2*nnwjt:mhp : 1acke that?

Sea breezes are often encountered on sunny days at the sh0iq3xr st 2+mx0d ,b 14gmdstzore of a large body of water. Explain in light of the fact that the temperature xq1m gtr+b, dz3td0s4s ix2 m0of the land rises more rapidly than that of the nearby water.

The floor of a house,b g.qjsmxdt1lc(g 7ch 5(s9 u on a foundation under which the air can flow is often cooler than a floor that rests directly on th5.m c t1ls( h,jbu9d7s(xcg qge 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 temperatureozd j(qv -q 6q v +/bvu.uz:,04dclcyr readings are always taken with the thermometer in the shabcd/(j+ucr l,v . 6 yu0dv qz-q4zqov:de.

A premature baby in an incubator canx fj tg5(h3i;l.lul5g be dangerously cooled even when the air temperature in the incubhlgtjg (.lifx;l535 u ator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–o*qxq o*;+r 1f 2pu4:ewcmhuy15), and why does it have a vacuum between its two e ;y4q:xo 2o+c 1urhmuwf*p*qwalls?

Imagine you have a wall that is very well insulated — it 6 j e.m1w7),(g jcbo)ylw jyjhhas a very high thermal.w61ejjowyj7 ()gym cl j,h)b 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) ventilatii 6selrl; 4wlq t*;4 xfz)iw5gon around edges; (2) through the frame, particularly if it is metal; (3) through the glas;zx;gilt6 4qr *w5 wfi4)e llss 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 metaxo q ;xb8p(qf .1tts0jl. Yet the wood feels lefb0 qoxq1.t( pxj 8;stss hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather imvyf 4nl4s nb:pn 1.n:ghn8.vs clear than when m.n h4 8n: vyn:pngb.s4nvlf1cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Expla )+pt vo,aoqun:bnkg 9/q kl)1;rs .ujin how it can help to keep an ol uqrb ut+a k:op/;n)qgn 9k 1v).s,jimmobile person warm.

Explain why cities situated by the ocean tend to have less extre mg0vl)ylas*e;0) /phphah ;eme temperatures than inland ci; eyghe0a/))sv *p;hl0lhamp ties at the same latitude.

  How much heat (in joules) is required lcx7j v7+ y-bm(zvy:o 1z* dhtto raise the temperature of 30.0 kg of water fr t-o v1j h(x7yb+7yzcl*dz:mvom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of het))2 6/oiqo:w e4cyyjaz 2ke dat raise 3.0 kg of water that is initially at 1wze dyc)yj6ikq/4o2) e:2 aot0.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes ado29 xsiu4eznx(r k;-z+9t nxbout 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 az p bk :gi339+lbg.r3zifqf8m unit of heat in the British system of units. One Btu is defined as the heat needed to raiszz rlgbkf8mbi9. f q g:pi3+33e 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate g3ya q7qm cf2i6 1yhe*$32,000\,kJ/h$ 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. Est)bd 3n xfje ; )4lwrvfnp(x15rp )e,gbimate how long it will take to heat a cup of soup (assuj, gdl(pn 1 b3e)fbn5) vfpwre)4x ;rxme this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the bra*)p al aiwj1,2hhxxr2 +hxv,ikes are used to bring a 1200-kg car to rest frow)l,xx hr* ,j2+p1aix h a2ihvm a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How man8 2lq6ovz 2cuch heat does it absorb if its tempe2lvca8n 2 6oqzrature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a met75ytjb- b. ajkal substance if 135 kJ of heat is needed to raise 5.1 kg ot-5. ba7j bjykf the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, ux rr 9q;km*nwe7c6 2xand water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their mass r*xr9nxk qe 6w2m;u7ces? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer +kv9(c 7lfk(m at vwxs.)xp-freads 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 tebdo6efw9, d(3f wcqk1mperature when a 245-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 = 5npkh jykk:9qi:r +w8$0.4\,kg$) 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 to1q.xo (b,eexljh;r5k 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 i3lzhk4m(rbrr;i(/ qv nitiallrm(zr q (kr3; /ihvlb4y 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 s(o1 g fv dck*(e2p 811ri tzun4nuq4mfollowing 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 calorimeter c(p4u1 uc2omv *gnn1 ( ds4qi 8ekzft1rup 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 atvwarb 8 349ezj 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has a c -mcj u+5fmr zo(t, evg77df4speed 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-2r ihael905) v huvqe an object is defined as the amount of heat needed to raise its temperaturl0uher-i5q2 ah) ev v9e 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 mesd /n -skms +fsx9r9i4lt 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. Ifmct pgppky5 sz z-+dx)v0 -6j* 65% of tv-dpptyz*6z pc5 +)j-ms0 x kghe thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a personsn9pp)il y.7umnb/hwwh3 03 e may give off 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has been losbp p3h9/y wmi7nl une w3.sh)0t?    kg

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

  A 30-g ice cube at its melting point is dropped into an insulated -( 1)vpi. jfzb.ybowscontainer of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a laten vzi.yf j.os(pbb1w)- t heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the freezer at -civ c/h79js( w8.5 $^{\circ} C$ 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 k0cz14d o2na rtg 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 b-)i6 )rb,le( lkrc rya j.lxx.icyclist consumes 8.0 L of water over the span of four hours. Making thrk i ya)rl-6e(xl. b).c x,rjle 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 consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 10/dcq ; 87vmpycgh(q5 j0$^{\circ} C$ 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 isc6;5at s ubig7wx.- qq r0jq7u $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 mi4nj odq37+n 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 moving aticil13a q/qo3 $6.4\,m/s$ 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 8.2-2 . enypqk25boz*l; leg lead bullet that was stopped in a doorframe apparently melted completely on impact. Assumye;.oe2l2n lqb5z pk* ing 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 is kep; i.gy;uw9 hxn* ez7knt 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 i kd* (s2tuj ql8x8 :;dnajzzfi-kh94that there are strong gusty winds and the extej qiz2 8hszx i ;a:(nd4k8*d 9fkjltu-rnal temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten ssn,a 9i, sj.r 92hwcpsphere (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 200 W of heat flows by conduction from a( z c5z.8mh9xxk e8tcthe blood capillaries beneath the skin to the bcm.e8z(9a x 8hcx5zt kody’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-thi d(rg3 7in8duick brick wall. Because of a number of 100-W3 g id8ndr7i(u 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 ice at u6d00wa-s- nc2 f0spq rbnvy4 v clb*: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 ccr1/ja/txtm c .g j/k(v7y4 l-usobi9ross-sectional area are attached end to end (Fig. 14–18). The copcbu -xokgc7s y(jm1/ t 9ai4// tr.jlvper 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 constant94 r4 ck1qzb2+phptm m, estimate the rate at which the whole Earth receives energy from c4tz9mr4 m+p2kq bp1hthe 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/ gc-gbttj-nhg */8a g f,m4lg glass bulb that has a radius of g b8n,ttc*m g-j4-h/ggfgl/ a3.0 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 btrblf +; z5nm-k 0w(tmainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in rmfwkn-t0+5(btzl; bFig. 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 hby m0(0sq2 g exk6)kjyas two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flowj ks 0q x)6bg(m0k2eyy 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 11.0 kg94jw,8dsxyr1,z m b dy 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 a+zoj3h9rv oo6 bout 0.20 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 energy is contained in ims zg+x*lz.,d6vr 0 ethe 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 waigm.d0*+ v6s,l zzerx ter for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood w q7 sz8kf/zqdwv)3 y*iith a mass of 1.05 kg. The block and imbedded bullet together absorb7)di*f/wy8 3 vqskqzz 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 radiatmku u;j)q26 vgwrj5m)ed into space by the Sun, assuming it to be a perfect emij w k2um;rgm))q j6v5utter 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 ged hld3m8t -nkp-iw;h7a9-:jj w *evnvnerate $200kcal/h$ 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 f+ky 0r+e cswu (w6w q(a+hy;4vsag+klalls a vertical height of 140 m before striking the ground. Estimate the +slaw( k ewhy6ywg+0avq(4k; +u +rsc temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water initially;w7p3.q)frn bj1qm dvs4ky 7a at 2b snqm4)3p ; 7j.1qd7yak rwfv0.0$^{\circ} C$. 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 tota e c13)6kvb1v.htr dtnl surface areant3r6tb1e h1 kvdvc.) $1.2\,m^2$ 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 metabolisdgfrcv(w8 gzm7:2 2 upm 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 conduct2lmfh98lpa6 hn 6on i2ed from the interior of the body to the surfacehlmf86 22ia n6onhl9p. 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 wall6jmxb h ty2z,2h59e m/dk xfv(s 17.5 cm thick (assume conductivity of air) and areh 29mv heyf xkx,5m(6tbj2/d za $410\,m^2$ 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 trave 2v(.sx7enxp3lhw) 0 w1a hpjaling 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, take into a5bx pq+j( d*( paq3h- mihp:laccount radiation from the leaf to calculate how much water must be tbj:i3(mq-(dxql + ha p5pahp* ranspired (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 atmoor)y - 6udhcd6sphere. If its initial tem cyd6h)6udo- rperature 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 Earth’s crust increases ab0 7mpvixqa,bg79yvx: kt3 yj --9mwgsout 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 peo 3wtgebq*4i( tple hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hitsb*qt4ig( ew3t 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 resl;sd.+dukl (j;2m y sault when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and radiation a5-wfvh q5qz2y ct,c if,;cac 46 bbp.yt a rate of about 200 W. Estimate how long it would take for the body 2cb vcqc zia-,c y t.;6w54 bqffhpy5,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 in t ob9/u8fu v0 u8kpkmu/)e ec,ohe 50-gal (185-L) water heateru8euk/0f8 ko9bu/m)vcp, oe u . 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 oc bp:y,ish 4na3cb e:02;wuy xf 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.    $^{\circ} C$