What happens to the work done when a jar of orange juice is vigorously shaken?*/.ism e ll7 fk*lmcr6

When a hot object warms a cooler object, does temperatury:uxt rqz+ 1fwdnu gs1/07j4ke flow between them? Are the temperatutg /dk1ns +zryx741wu 0f j:qure changes of the two objects equal?

(a) If two objects of different temperatures are placed in contact, wilh6,nm( rjrmrs9bs; lxm 8r*2pl heat naturarnhsp 8jmsx ;rr,9rmm2(6b* l lly 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 wherecs tj ,3vt;-43diolkg tropical plants grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing g,tk3l t 4s-divoc;j3 can be reduced by watering them in the evening. Explain.

The specific heat of water is qui1*n+4 *njv6uanf0nv46 jrd :z pwx dmmte large. Explain why this fact makes water particularly good44m6z:vdn6*n1 wra x* nfj0 u pn+mvdj for heating systems (that is, hot-water radiators).

Why does water in a metal cantgc32 zy cd -dwf5a2 f/hoc(fu-een stay cooler if the cloth jacket surrounding the canteen ucd-w-hc z(y5f2 g/fdfo3c2 ais kept moist?

Explain why burns caused by steam on the skin are often morelf 4l9utfi*b93o jz* v severe than burns caused by wato* 9l3*49bfzi vj fltuer at 100 $^{\circ} C$ .

Explain why water cools (ifoal92.a awg v(-f8bj nx ;st;ts temperature drops) when it evaporates, using the concepts of latent heat and intea (-wb xgsjfnv2;a89a;l .t ofrnal energy.

Will potatoes cook faster if the water is bw1/vgkx/e .o gzgtq, faa )u24oiling faster?

Does an ordinary electric fan cool the air? Why/ i(map hpc u6y99ezl8 or why not? If not, why use it?

Very high in the Earth’s atmosphere, the ,zyl 6iklq0em rnw 66,temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering themselv:6 jg nevtd /.3vnqw*ces withw:6 dc3v g tvnej/n.*q snow. Why would they do that?

Why is wet sand at the beach cooler tbon gawjx9 :m.a*g) ;to walk on than dry sand?

If you hear that an object has “high heat content,” does that mw x+56letpl7s98qqkr ean that its temperatxp r5wlk8ltq69 + e7squre is high? Explain.

When hot-air furnaces are used to heat a house, why is it important tha:azq9 p ajxu3,t there be a vent for air to return to the furnace? What happens if this vent z:ujpq, a39axis blocked by a bookcase?

Ceiling fans are sometim6 )yw1f.qlgwd es reversible, so that they drive the air down in one season d6l) 1qfwy. gwand pull it up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches or centp33g4 jfwt7phimeters of loft, the actual thickness of the gar4pg 7f3hp3tjwment when it is fluffed up. Explain.

Microprocessor chips have a “he;b*bg (q j1ncx zxe.3dat sink” glued on top that looks like a series of fins. Why x;c13(.bejnzb dqx *g is it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a )odyp 5zma lper/x:3 sf(+g5llarge body of water. Explain in light of the fact that the temperature of thd)l:g/f+e 5l3posr5m ax( yz pe land rises more rapidly than that of the nearby water.

The floor of a house on a fous fd8h3m94 6finufb0*ot qm2yndation under which the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundm8st3 fyhqob 06nfdu* m 429ifation). Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature readiq h4m5y z 8 (sozp0phg-p.nw*engs are always taken with the thermometer in thsm5 (4zh. q*hzeg0y8n oppp- we shade.

A premature baby in an incubator can r:x tqkyc9-*ug1x- sj be dangerously cooled even when the air temperature in the incubator s-rx*gq9 u1y- jtcx:kis warm. Explain.

Why is the liner of a thermos bottle sek v,bb5cm*7(tq-cmag7 s hna(4c3 l uilvered (Fig. 14–15), and why does it have a t a3c7cv b5ch*a gm(,nl(-qesb 47ukmvacuum between its two walls?

Imagine you have a wall that is very well jo uhrg*vnt1j/i2j,;insulated — it has a very high thermal roj*jh n21igv;, r tu/jesistance, $R_1$ 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: (y 7bv0b/la *qvh nm8m*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 i *bv/7mb8la q mhv0yn*n detail.

A piece of wood lying in ty 6a/ bt- uchtxj/m)r,he Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metch) br/, 6x-jmu tya/tal when you pick it up. Explain.

The Earth cools off at 0:4kyyha9gg y*6cjx rnight much more quickly when the weather is clear than wh*ycjg60y hxy rakg: 94en cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plq2* 4i:) fyqqogkip3 hj*wfc, astic foil. Explain how it 3if4k f2q *g, jp:iqcwoq y*)hcan help to keep an immobile person warm.

Explain why cities situated by the ocean bbqv9xe r/49l tend to have less extreme temperatures than inland citiervb9/ b4l9eq xs at the same latitude.

  How much heat (in joules) is required to ra3yedo /-mt (hzise the temperature of 30.0 kg of water froe t(/ dmh-3yzom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 pym bwy 3*+0ol7j lgo2qix0tb 9rm w-3J of heat raise 3.0 kg of water that is initially at 10.0 o 9*p+70y23 i03ytm lwlmwbqro b-gjx$^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2 dpkhku(60 gk(lk0;wl(n6mr9nd6 7rmo ,repr500 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 Britis djrxx wf8abg57 hq41p h*m-g:h system of units. One Btu is defined as the heat needed to raise 1 lb of water by 1 F*qphx7wj-xm4h 5fg1: 8a brd g $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can geno)mt;fme hn2 +r,s4c1e era5b erate $32,000\,kJ/h$ 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. Egjefqii4)5x(g . a3 gystimate how long it will take to heat a cup of soup (assxi(.)y3iafg4qeg g5j ume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when,v-ws9x6 yul/2kjtf x q43fpf the brakes are used to bring a 1200-kg car to rest frls 49uwfx6pyvx 3,tf2 k/qfj-om a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of k dt ,u1t.d*abo(, 9 dqyargn9water. How much heat does it absorb if its temperature risk g(9 dt,douy,da9 b.n*rat1 qes from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is nee 1i g;o:)8om1ggpmfp lded to raise 5.1 kg of the metal f11mg;: fpo)8p igmlg orom 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature rl( dvr kv35(y) fb0xylise when tkl0(5f)l yybv3 r (dxvhey 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 thermome5j/ d s)g62d,iaqf zcoaw x91dter reads 21.6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibrium temperature when a 245-g block of copper iv 5,+ +is;ai*ieawnoat 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 horseshoegtl u6zse 3d+)qq/)fp (mass = $0.4\,kg$) 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 iqck kfx/mr6+-o rfd) )s 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 to2vy z+f 4v:2 rr/auzjg 4ml*0 my+grnb bring to a boil 0.75 L of water initially/2mv+ym rn 2v4* r aufgg:blzr40+z jy 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 measuremeyq zj2a8-; mtn6:bwa jnts. A 15-g sample of the candy is allowed to dry before putting it in a bomb calontwjqa2 bmjy6a: 8 ;-zrimeter. 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 + q .4a loa,ia1zf5vn0v:shlvat 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; l,8 xk gnkj3 yl3c.ll84b 4fe.pzqcims+zo3r 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 amount of heat*d)wroba3p,pn3t qnt 53xf h. needed to raise its temperad5 3q,a)tnprtown x3*fp.bh 3 ture 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 initialoxqi pav,o;10sv 1jlvzb55 , ir cq11yly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof ox-hhk q7 ofn:lv2;)w.of 0rdq f a 45-m-high building. If 65% of th-7h: qo0vod.;r2 w)n x qfhlkfe thermal 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 evapor)zn) w6txl)p -:vbdax- d rdi;ation of water frxvrdp6w )))d--n: tlab;i dxzom 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 pd;9zml s,k. u- zysu5;c4evr of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K an-ue ;l.rzkzv u4sc;dm psy, 95d 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 p,/xcbx4fy+y $^{\circ} C$ 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 kg of water at 2k3s1ec u q v8;) b+p5ialhamj18$^{\circ} C$. 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, asm1 (y3ylu.vxmtp- s0o ;t jilpr 3(x; bicyclist 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 ri y v(xl3siumsm-j1ry .o3tpl ;pt;(x0der 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 10d(s9v8a 14hdw3oqvd 0jht2n peidx7 00$^{\circ} C$ 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 i wsfe0x1bz :9ws $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 at81iykagn.;rslpixmy4.g p * ; $250\,m/s$ 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 at4(nb - bno.vhiamdaa/t97x 6t $6.4\,m/s$ 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 forenh tf( etj3ky7uwkniplw*h8 e8u533e4pr i:b)sic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently 3uhi(jp e) klyht8b:i rewf75puk4*tw3 8n e3melted 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 di ppzif1;g: g:mameter of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduction in Examp*79ilcs(a omgpqo1,w le 14–10, assuming that there 1wos,c97l(agp qi*m o are strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emilqp9o,+xv k 7rniea y3:-;wedx : r:xyssivity $e\,=\,0.35$) 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 b g1r7t:l6rwvtz/hzde: :r xb:d3 ig d,y conduction from the blood ca6dr /w,r:hr7zvi t:l d:tg3:e bd1gxzpillaries beneath 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-tha5+g0ad.a at o ej03wl+8o etzick brick wall. Because of a number of 10 0ze85d+ 3ltwaao.g tea+oja00-W 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 melt5hjjhg7) op:z51t,rj wyvus-ahs x.; 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 length and cros 9 pfor.guksxg-o,r4piq9 -, ps-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temp--,f, 9gus prqxoro 9gk ppi.4erature 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 who7-zuk2pi.,:t grab aole Earth receives energy from r.t7a 2ou,ab-zpi: g kthe 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 dissipadmto:qi9 8 q*nae e9 c:;0quvdted through 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 inner and outer surfacesqu:i9d;qc: ndq* e90 evta 8mo of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come maur3zbno25(*pcnil by6( c, 8y nyeym:inly from a 4.0-in. layer of brick andm,l:( uyn*8e 5c(iyr yy z2b nnp6obc3 an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has twrzrv k 03rx 9pd n*c.lc3su4w-o panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flol3 9xkc -prv* zcdru4rsn03.ww 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 vafzx+kv/3m m-l)y2e.pmcw-+bb yr; 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 k2fma h3z )2e)s6 yqmesg 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 world’s ocejft9 uix467 xians, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water 796tijxi4xf u as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed uqjzk ; 65kh:g no+jx;w2r.q(h w0qq xblock of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. Afte(+ ;:o2; wk6g u0k zwqx qrq5hn.jqxhjr 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 intoawsqr4c :(8km space by the Sun, assuming it to be a perfect eack48qm (:rws mitter 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 generarsav kxuv/9w+:x zxli )x5vp35 .tk1lte $200kcal/h$ 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 rb,yk gs3cbvzc/c -1 z:olls off the top of a cliff and falls a vertical height of 140 m before striking th,c-z b 1syc c:vzbk/3ge 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 into a 2.5-L insulated pail of water inikvx4pry e3n)p l+l-b89( ptbxtially at 20.k(rpl ny9 +eb 3p vl-xbptx84)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 total sur90t 7dh 3vpsllface area ldptls0vh 7 93$1.2\,m^2$ 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 0ltti8 ux2v j6average 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 in 1u w:yqitsvius *2v.;terior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is at i v .y2s1twv ;qu*i:us34$^{\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 agbrxsaj 6i;4:.-w ozt( s(ydvir) and as jgi.ao-:rt 6 sz(w4v;xyd( brea $410\,m^2$ 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 travelko l 0 q,4ix,b c4dd,xfr-m:tting 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; u,uabom.skzw i5: ak:d3 t:,ku9x du into account radiation from the leaf to calculate how much water must be transpired (evaporated) :wa :dbt3 m.:kos;i5 kux,z u9uad,kuby the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphextz7k3z e)y 6;3 ix,th fd8hware. If its initial temperature was -125iz,t38;ekfht ) 6 zdh7xa3xyw$^{\circ} C$ 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 th nqsxrx- x3+h5b-(zw de Earth’s crust increases about 1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit a softp vd0vibq.:n+ /k5 pzb rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the bal pib k+qz nv5/:0pv.dbl 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 re:g +bwxuhi4i .mos,:c sult 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 byjlhb0 sn*:2 bbf s5,xa conduction and radiation at a rate of about 200 W. Estimate how long it would tb*:a xjsb,s52 h0nlfb ake 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 hot water” left in the 50 zef 0ey(;3b3yk7iu lz-gal (185-L) water heater. This suggests that the t 0ey; zil3(f3e7zkyb uank 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 glov8c lf/9ya w-ass surface 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.    $^{\circ} C$