What happens to the work done when a jar of orange juice is r6 r sx)t4:v,ukp05ws- eh qqzvigorously shaken?

When a hot object warms a cooler object,5m8rtk-y81yyj 35pmvkxjk )/zlknh* does temperature flow between them? Are the temperature chang1knkr3)m kyk5 8 ymlj*t-h/zv8 x ypj5es of the two objects equal?

(a) If two objects of different temperatures are placed in contact, wi7v +lb.z5 kswsk;o vi8ll heat naturally 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.+bzs.;k 7l ks woiv5v8

In warm regions where tropical plants gro hx6 /(al xftm0mv6m1jw but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by wat6h1 mt lxx6v/ mamjf0(ering them in the evening. Explain.

The specific heat of water is q5uuqop-t*tj z:gja:: lt5qq ja;t0wk.* z5csuite large. Explain why this fact makes water particj uj 5c:*:wtqk azjzso .l;qut5 pt-:50tgq a*ularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jackervi;t7+g und3 t surrounding the canteen is kept mois ndu7rvgi t3+;t?

Explain why burns caused by steam o65f0ibfuh l ;s879pvzn s9wiin the skin are often more severe than burns caused by wat9u nl ish80izbfw57f6v; p 9sier at 100 $^{\circ} C$ .

Explain why water cools (its temperature y;kqi8,gu8x /oqr 89wmjnb 0gdrops) when it evaporates, using the concepts of latent heat and internal onyq g8,/wukr0 gq8 im8j;9xbenergy.

Will potatoes cook faster if t5+wmw ef/b4 hqq5zu0r he water is boiling faster?

Does an ordinary electric fan cool the air? Why or w bnn5 l4vq.km wd;lu;:hy not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can 3qajaqn 0p+sat20h e uno-9 .qbe 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by coverin 7 c57ix1 sgfex-xw+ qug*+vwyg themselves with snow. Why f5x vu1 x7+7e+gc ix -gsw*yqwwould they do that?

Why is wet sand at the beach cooler to walk on than dry qlt.(l)y tw+xm 4z 1nch* zxf,sand?

If you hear that an object has “h ux)zim eos+9:igh heat content,” does that mean that its temperature is )m:z9xo+use ihigh? Explain.

When hot-air furnaces are used to heat a house, why is it imporkkmd/k/snzk2kg f 1,sn2f 2;atant that there be a vent for aiskmf, ks;kk nf2dnakg2/ z1/2r to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air downs 1p-4csyhaioqj k(o4kl: 4,3o rzep( in one season and pull it up in another season. Which wor,sae(y hk ojz4 c-4l k(13qi:4soppay should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so manyqa.gb h:j r00g(xgcm6+ z.vv7vgf-gy inches or centimeters of loft, the actual thickness of the garment when it is fluff-g.: vbj ca6xg zgh7g00rmfqv(y+vg .ed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks like eu 8 lm2254veqb /givza series of fins. Why is 28mbuzi qv25gve4 le /it shaped like that?

Sea breezes are often enc 084c/0kvg 4eef klirlountered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the nearby wl04riclfvgk40 e8k e/ater.

The floor of a house on a foundation under which the air cansk -w2-a.allm flow is often cooler than a floor tha-a lwkl-sa.m2 t 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 therma/k- uf; ucn :pwf,e; 5/lhiqfometer in the;h-/ln c ui;qwkfu /5f,pe:af shade.

A premature baby in an incubator can be dangerously cox k 9owhc 2i,pajv/5paim 8heo+ss: b8+.5nx holed even when the air temperature in the incubator is wa h2:o h5/8+ 8. ksw9jsvhbeo p +cii,aapmn5xxrm. Explain.

Why is the liner of a thermos bottle silvered (F: eh0t4nrtslx7mx 8e +ig. 14–15), and why does it have a vacuum between 4x8 t7 nrmt :xh0+seleits two walls?

Imagine you have a wall that is very well insulated — it has a very high thermalj8k2*vjtkni,m7 s h0r resistancs 7jivh nm8t2 j0kr*k,e, $R_1$ 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 followinge g51)hnyh(xtwl.yvz5qlvsr 4 ggi. 6ig 4p;) processes: (1) ventilation around 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 radiation? (b) Heavy curtains reduce which of these heat lossge5hxvgn)t.gqi.;1r 5llyw s4p yzi46 vg(h)es? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a vqh+zln-a9ps2s ; ci/ piece of shiny metal. Yet the wood feels less hot than the metal ivzh9s-a q/ ncl2s+;pwhen you pick it up. Explain.

The Earth cools off au 0f* dhhx,v51glb ze+t night much more quickly when the weather is clear than when cloudy+ de0l*fbhh1zguv5,x . Why?

An “emergency blanket” is a thin shiny (metalk32vug m53e 0lfwuq*e coated) plastic foil. Explain how it can hvw03k q5el*ufg3 ue2 melp to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less exq1t hd c70++uqrphnr1 1ak /lhtreme temperatures than inland cithp1rd 11hrnc0/k+a7+lt uh qqies at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30hom 8g:rqkq8sa;r4p t9ynx7).0 kg of wate;og4n aqyr9qkpx8:7st m )h8rr from 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 initially7 i .ob5or8x/n a6 3f2fyidrbc at c. 35 b2din ra6 o8ibrffo/yx710.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active pers4 jjf;7b fdjt/on consumes 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 un4 /ulob0 u,(2qj(usydr bef4ixu, /i oit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 l0 //,bexdu4y qs,i4(fr u( ju2uobilob of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generarx k8iw,o0dh(aq2 /en te $32,000\,kJ/h$ 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 to /hepu)7kte+mheat a cup of soup (assume this is )+h kuetpe7/m 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brr**k:r olvqwcc;*1oacl h z;9 akes are used to bring a 1200-kg car to rest from*z:;rclc*ro vc;*q9a l hko1w a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it abso. sd(9nfbqip6rb if its temperqb( f.dn9i6psature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance ievgf1/ yt59*jdvh -3u.ss auzf 135 kJ of heat is needed to raise 5.1 kg of the m3fh95 tg.-j/uv yvuzsad*1 esetal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the samq +wac7 v5/ra(+sbypc e temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: b+ /vapws7+ a5ryc(cqSee Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rb/4)t,dgdtq h3x hod9eads 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 temperatu ;eo l3y2uu:nqre 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 bn3lv 5a(;n8v*l3z2:bhfn2iu pbe w.vrf h/ d= $0.4\,kg$) 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 substa.6nld9uadk*usje n*bg*e c 9/nce 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 uwp+,3mg *hptjv7pwz 691zasp* mu4p boil 0.75 L of water initiall +ju* mhpz ,*wzpg3mvp96uta1s wp7p4y 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 following measurements. A bmvf2(fx(2d9 ks zn*x 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 cup of mass 0.624 kg. The initial temperat(mv x( fnz* fdk22xbs9ure 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 a3f5pts a;v48ni.x 5z btjc *eyt 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 :5cx m(l6iv ikcb, pd:4igf5x,n+ iumhas 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 defined as the f oitfn8 d5y+/yoz z-:kj*xd 9amount of heat needed to raise its temperature by 15dz8 zytf: + */-odfknx jo9yi $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 16.50uou r- 7iveqv2d:ya:( 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-hi+pf soc3cy/-e gh building. If 65% of the thermal energy produced when it ho3e/ + cfs-pcyits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person mayoywc6/hzf64u cdz,gli/9c 9d give off 180 kcal of heat in 30 min by evaporation of h6i 94l c,uw/oczc9gdzd y6/fwater from the skin. How much 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 insulated container ofr6*6uwcu * tlg liquid nitrogen. How much nitrogen evapora*t rul6w c6ug*tes 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 taken from the freezer at -8.5 b rv:t4r95xb /yrp u-k/nxb z9$^{\circ} C$ 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 con0*gk9 rivw*pxtains 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 the span of folzkc. z-83a dour 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 consumed does go to heat, so our appro .-k8l3aozzcd ximation is not far off.)    kcal

  What mass of steam at e(u j)vm5vt r: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 mercury is7e12bo4 ut ydd $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 traveliavov+u8zfp* *j c 3go.0dpg7 *vap y7ong 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 lqthkn2j3 -ir7 ( p,vek .d-sj 5wf8ufc7i+ojat $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic investigator notes that the 8.2-g lead bu8,l ct9tyvl b1llet that was stopped in a doorframe apparently melted completely on impact. As19tlt 8cbv, ylsuming 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 s)- el m.og-gqaluminum rod with a diameter of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by condq x8v64wt3b(lcf p/g vuction in Example 14–10, assuming that there are strong gusty v8cvl3p 6x(w4tbq fg/winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (e( h4wv7jzwz 7adok .r0missivity $e\,=\,0.35$) 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. Suppo9e3yj;jztjwvn- ,syoo ) 7:um se 200 W of heat flows by conduction from the blood capillaries beneath the skin to the b)o - ,zu;jw7:vsyej jynto3m9ody’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. Becau(-c6i x 4;ukavss27 n ghvf0rkse of a number of 100-W lightbulbs in 6anhx i;7 s(fsvck 20v4 urg-kone 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 ua zm: tg6ah.d;db8. th,xe;n 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 t yx.x-9--q/:xcx p/bkxb jgr ihe same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperatu. r/- c9xyjkgxi b /xp-x-bxq:re 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 Eaik diqj-ah+ar) 37e 1arth receives ener3hiaq)r1aj -ad i ek7+gy 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 ;04zv4sband4h t* azi a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the ia4ai0v ts zd*; hn4bz4nner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house c oga).;jic(elhs+j +p ome mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as si;s( a elp).hogc+ jj+hown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separa8e j1l ll8g9qcted by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a wi l ejl8cgq198lndow 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 im0ki29 ie/u8 4pikz*u ghe;gj t take 11.0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0.20 kg oj* + l(5;dfkyi ie)redf 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 containede 08jks p*nxxt0wdlbf0oz7m y e/68j5 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 pj85z 0l00o 6yp *txbenmkwx /8jesf7dure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood wi93- fv(zr/mu cxh1yvb./trw2 di n6math a mass of 1.05 kg. The block an-m rw9uixfyv/r/31t ad chb.2 m z(6vnd imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming it to 8(sm aujd*so,be a perfect emitter at msa*ds 8(,oju $T\,=\,5500K$ 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 mwadkpt3lt i w,.5b d.4,e k0gyay 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 of a cliff and falls a vert fhzx4su.1y;r ip9+h 2la6 hfkical height of 140 m before striking the ground. Estimate the temperuify 1lfx zk+rha26 h.9sh;p4ature 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 avb3vbfmzj87g6+q m 0initially at 20.0m08zga7b q3v6mj+vfb $^{\circ} C$. 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 jackmfgj (3 l64u dby(mo;yet 3.5 cm thick with total surface areau f(m y6 (doy3;blmgj4 $1.2\,m^2$ 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 metabolism rate of ab4u kd cigvs39-/hp- nuout $950\,kcal/h$ 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 whi p)6bta by2rs+ch heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 )brbs 6+2ta pycm, 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 eqq 7xb*jk+ hxp5o,2fs;a,lnok ie56cm thick (assume conductivity of air) and area anh+7es oj6lx5expb,;*5k2qo if qk ,$410\,m^2$ 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 travelombsfp n) g8(;ing 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 wk cp4v1+srd)lyenb r* 98ywd03n 4nu58, take into account radiation from the leaf to calculate how much water must be transpired +rny lr 0dpnnd9v*13ww syebk4c) 48u (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 inh(q (p y-uk1:q9nhch taw)q+ iitial temperature (9qhhqkc n : 1q(-+ya)iuhtwpwas -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 kp3 wfgmo d+-ymy1b:7/7x cihabout 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 sq/6sdbhv( +y neuash (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assd/y(sv6+ hn beume 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 wj2* ae 3shs f((oybrt9hen equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environmensu e u3dorv 2:w5n x r;oi*o48lsz8m(zt, a person can lose heat by conduction and radiation at a rate of about 200 W. Estimate r35v l zd(uxeozro m28:n 4uwsi*;os8how 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 dishwashlsichha +t ewicbgv6 53q0x7b( 4 -/ueing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptish th 4(iu/x q6cv7bgb0lca3e -w+5eied 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 surfacehd/ff h+dvd6 vbcx* br9a. (*w of 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.    $^{\circ} C$