What happens to the work done when a jar of orange juice c*cy7 (l9pa kd*einxx w*3jn1is vigorously shaken?

When a hot object warms a cooler object, d)u;j:pbe pw0 r y;5bqmoes temperature flow between them? Are the temperature changes of the two obr;q up)pwbj5;b:my e0 jects equal?

(a) If two objects of different temm lw71w2ff4lq peratures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat4fllw fqwm721 to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropiyxu. w1 m+rl0+9 kyywfo;g3i(sgck g;cal plants grow 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 watering trylg;fik1.o(s ux gw0;++y 3kyc wm9ghem in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water pa53th ;7y mp*1ly ya.ogxlrsv+rticularly good for heating systems (that is, hot-waystyav+1y.o37 g lpl;*r xh5mter radiators).

Why does water in a metal canteen stay coovyv)aq-oe 8h5dy.i lb3 g3lf5ler if the cloth jacket surrounding the cante5 dellahv3y)g.of3v b-5 8yi qen is kept moist?

Explain why burns caused by steam on the skin are oftex5 nb3s rlu,l-n more severe than burns cal53xu -b ln,srused by water at 100 $^{\circ} C$ .

Explain why water cools (its tet -+xr;9gm cl :67g;hpzse 1cmcwccf 4mperature drops) when it evaporates, using the concepts of g et9mxh4 lfswrccp mz-7:1 ;g +;6ccclatent heat and internal energy.

Will potatoes cook faster if the water iz-s3oz bvibry58 ,pg -s boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If noauh3yqd 614*g+eotlut, why use it?

Very high in the Earth’s atmosphere, 6).6-: 47ofhygykpfe ozie wc the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have 7u73+uvk)i m k sq7olqk i*4gfsurvived by covering themselves with snow. Why would they dul3 ) v gim7iqfqskk* k+747ouo that?

Why is wet sand at the beach cooler to walk2 kqwh5(gup37q rxz 8;ihu wr8 on than dry sand?

If you hear that an object has “high heat content,” does that meak6 i1;lrsf y11s h:qrrn that its temperature is highks 6 s h1yqfrlri11:;r? Explain.

When hot-air furnaces are used to heat a house, why is it important that theu3seutjif 2 flx8:2*ure be a vent for air tuul8*3fe:s f ix jt2u2o return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversvnvsb;: yd u w,b..hwdy) s/;zn htr()ible, 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 summeh;d. ),.yt /s()y :b wzvnrndswbuv;hr? For winter?

Down sleeping bags and parkas are often specified as so man i+* kg3g i2tic.wf.7 2seqg8lo+ninby inches or centimeters of loft, the actual thickness of the garment when it is fluffed up. Explaiqiiwtc+ lsggo+.*7ef b2gni8 nk.2i 3n.

Microprocessor chips have a e27ogo*m w;rsy o,(s t“heat sink” glued on top that looks like a series of finsw2or *mss tyo7g;(e, o. Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large bodyv1lk+zjvlj :* of water. Explain in light of the fact that the temperaturz l: l1*j+vkvje of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which thlb5ud g2jycs cm6.yn2k)w 26mv ( crh;e air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Exp g65nr) uw2vcsm;y.ky2cdjh6cb 2m l (lain.

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 p1hky) k/ 1noltaken with the thermometer in the shade.plk) hk/n1 yo1

A premature baby in an incubator can be dangerou4.7tba/q8 qp(yl zhze;xt8 wk sly cooled even when the air temperature in the incubator is warm. Explaiqbewl x8tt48z zakqy ;/.7p(h n.

Why is the liner of a thermos bottle silvered (Fig. 14–15),vhcmk ,y zz /dnb.+g+-b-hi ,y and why does it have a vacuum between/h bz-ckidgv.hb+yyn,+z, - m its two walls?

Imagine you have a wall sbk g(wsch,*c(e io(1that is very well insulated — it has a very high thermal reih(s c( b1g*ck(wseo, sistance, $R_1$ 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 5no.2ij e ximc1pz42ewindows by the following 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 losses? Explain in detxnc2eip5im2j.z 1eo 4ail.

A piece of wood lying in the Sun absorbs more heat th u i*3)h9uijbuan a piece of shiny metal. Yet the wood feels less hot than t3i 9bujiu hu*)he metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is cleptw+* +t6el ypar than when cloud y+tepw*tpl+ 6y. Why?

An “emergency blanket” is a thin shiny (metal coat p+x*w1vtn/z2nm 5bpjed) plastic foil. Explain how it cppmv1j5nzx2w*/n +btan help to keep an immobile person warm.

Explain why cities sfjbxquuk6387 9ydq, + 1 flln(+jvfy+y2i hew ituated by the ocean tend to have less extreme temperatures 1b,fy fyu (w3he2f7nqyx9l+8k +ujd vqlij+6than inland cities at the same latitude.

  How much heat (in joules) is req++uo+ mo 3zkdfuired to raise the temperature of 30.0 kg of water from 15 +d 3+zmk oo+uf$^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 770t2hy3sjii c, uu.+ q-t0 J of heat raise 3.0 kg of water that is initially a3it.hu+2u iq-yc,t sj t 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes 8 zh l*vkk: b7(s n8aqk 3lwyozv((7puabout 2500 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of heat in the British system of unitsy yo). ca)bna6. One Btu is defined as the heat needed tyncaya.o 6b))o raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generatez-gj t6lb:rw r6 u0pu8eui9/m $32,000\,kJ/h$ 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 ho6-ykijq q.2tqw long it will take to heat a cup of soup (assume this is 250 mL of water) from 2q2qk. q 6ijy-t0$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories mzk 3l;)x-ftk6tx2 py are generated when the brakes are used to bring a 1200-kg car to rest from ttm 2pz)kkxxfl;-y3 6a speed of $95\,km/h$ ?    kcal

  An automobile cooling system h9j/ufedf r hxi1;)3rdolds 16 L of water. How much heat does it absorb if its temperature risffireh9;/3jx ud1r) d es from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a mcrl165dyl +0lw xcp 6zetal substance if 135 kJ of heat is needed to raise 5.1 l yd +16wcl z5c0p6rxlkg 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 the same teh tr84isyy+dvkd9 n87mperature rise whenht sny98r y+47 kidvd8 they absorb the same 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 read4 as*a p pjazjmf7w fpbd1o-c2 1*.bx2s 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 blockl3j 7 j-aihij,o9hbl(wb 3 gg+ 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 (m lw6v3fgvwhxk9 o (rk2un n65,ass = $0.4\,kg$) 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 substancolq:36ysrtle 4/6mx qe 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 0.75 L ot14hy 3(um) xm6u,iu msc ehu.f water initially a( )cm mh3uuimutsy16 u e4,.xht 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 fol47/g8(nt;egovv i9kk: yk hpvlowing measurements. A 15-g sample of the candy is allowed to dry bt9g:vygvk 47vn/ ke io8(ph;kefore 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 4f-;ls tno,jb;tot3 jat 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 hamme;hg f6tib5 7nlr 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 defined as the am1 bnv )fj:h8ls h69rzgount of heat needed to raise its temp 9fhzbh)g6:vn8 jr sl1erature 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 qq0w,xp88l brvq uybr9( /;x pinitially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the rolumt0 r+ zn9n/of of a 45-m-high building. If 65% of the thermal nn9 rmlz/0t+u energy 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 evapora -n-kyu5+m jtytion of water from the skin. How muc- 5t- +yjuymknh 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 containery2.e/fqjhs*(e+ fwk l of liquid nitrogen. How much nitrogen evaporates if it is at itf wyqk e*hf es+.2(l/js 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 d91z;xd,uc e dqoq 7v6mv:3e;iuds 0l-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 83 ,esc ug0+7w 1z ra*ctse dt93ai5fe*c0 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 m5cs7b*x j20 ofu* zzithe 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 ri70*z *ozfix 2mj ubcs5der 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 10u( bvy;fya5f a8y(b( tf)b2 bl0$^{\circ} C$ 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 is p ;vpiyh.4c9; j ejv/o$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 at lmcsu9 4:-cbdo2m nw 8/ga4aw$250\,m/s$ 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 mov0t:2mf; nuo j+ngne6j ing 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 forens 26hqr.ed1a wlic investigator notes that the 8.2-g lead bullet thaq6l2.hr1e a wdt was 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 diameter of 2.0)s74h4w8vl2 ea:hfad1jhlr t5 :a fzh 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*hb18gkg/o mux.0; l:hwxvb n, assuming that there are strong gusty winds and th1 hwu: x;bx/kgn vg0lb.h*8ome external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivss kkpu87) ok;c q(b48lghik)xb 8yu6ity $e\,=\,0.35$) 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 conductiou c oq4v.n z3u0 dvc,2j3ytc3.d;grkan from the blood capillaries beneath the skin to the body’s surfq;vo4z k03c.udud,y3 rgt.jn v c3a2 cace 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 brq06mwmp5a:s) wji d.qick wall. Because of a number of 100-W lightbulbs in one room, the air i5.qm 06)wj q:asdm wpis 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 atd c/vyw hi)d(cq9uo q-13/zedb; :dzo 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 pum xhux+-o7w):o7ato(iag)*o41nvp n2 sz d cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a - oou+)onap pohu s1g7x : zit(vn2*w4)d7 amxfurnace 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 rw bog:lufa-si/6vuv) 7v 3-m date at which the whole Earth receives energy from the Sung/vu l- v)oms3f-:aiwd6v 7bu.    $ \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, whicxar4tv2khq 2,5kw+t eh is dissipated through a glass bulb thak+ 2wtet2 h,arx54 vkqt has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall+fc2 vm lzh.5b8gk2 2sn9vq;br ,mbtj of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of ins hv9zm+2l 282j gn,5vcsb.k mf;rbqtbulation, 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 panes of glass separated by ann735z co54m vpikv(z kc qgg4* air space, Fig. 14–20. (a) Show that the rate of heat flow through svz447z55 o mk( g ikp3cnv*gqcuch 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 ta:ac 2/p 7hg+m3lds lfedydjy:iw(6o2ke 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 rd1itv b0s cnb-g.)2 p0.20 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 the world29* gr2q3t5xfn0yd g;kis rd6kisgb5’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 water for if26ddrryxi0tgg 923b;s gk5 kq5n s* this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood with a m:pwl55mwdyb+: k 5f0 xw*d8 mgp3q cghass of 1.05 kg. The block and imbedded bullet togwp*yh fxm: +bg 5wd qlwp853 mdg5:k0cether 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 oyhla/6 mi kuxw 1s rjm188gu*6:evl;Sun, assuming it to be a perfect emh/1yav uixg1k l86u s;:8w 6 o*jemmrlitter 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-q.d u,lcfha;0 )l/t9va(eu+p7vsnd x kg person 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 tbnx6,avrj.do 04mc9(s(z zdbop of a cliff and falls a vertical height of 140 m before strikinbd6(s9x(z,ra j0n4 cvb zmdo.g the ground. Estimate 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 dropped intjtkwk1i x0i) q:3o l g,k 1qh:cm88mqvo a 2.5-L insulated pail of water initially at 20.0qk kj m w18h):1ovik3xmic8g, 0:qtql $^{\circ} C$. 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 as:,k ufj0f k4u goose down jacket 3.5 cm thick with total surface area0k,s j:uf k4fu $1.2\,m^2$ 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 metk2tvish g-f a la.7bwcgu1- 75abolism 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 inticxbg x: i,(d gt+kl41erior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is at:xb (l tii+g, 1dg4kxc 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 conduco,a1v;tlt8t wfa82y :sc7 gfgtivity of air) and 2 8s gytvtf;t1af, 7c8l :aogwarea $410\,m^2$ 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 travel+22ow0ff5ei 9rfszr f;k9xda 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 58, take into account radi/,56e/ffti yslri73h5 x qr xzation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hexl3t/ ixzqfir/ 67ys hrf55,our to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters thers6(4yb30z cf:gv tms Earth’s atmosphere. If its initial temperature w3vfct:zr ssmg0 b46y (as -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 about 1l1a6h51s gw 6w, sjn 0iv8smpm.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 8oll.* r eaneyumv8p6+/t z5za soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits*m8 /y zouelz p.r6a8+e5t nlv 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 masses of ice at 1s ct/v,)xgkpx)k 0qgqsv4o0 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction abd74oq/jqm r c eq5fe,t+:4 8qiww lc jyix:-0nd radiation at a rate of about 200 W. Estimatef/e:4 8+q j ltqwcyix4q5:w-0idj ob, 7 rqcme 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, there is “no hote022ks (r(/kw f6z rc0kzaiz n water” left in the 50-gal (185 (z(kn a2 26wk0ekzs/i crr0zf-L) water heater. 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-W lightbulb is vrkq a3(tks yl.25f1h 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.    $^{\circ} C$