What happens to the worx4 h8bsl 4 ()3)zikeh kjp+dva 0jbkf4k done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? Arvnek g 4fx;- 66)k pviy.kb5dge the temperature changes of the two objects ekk gnp46 ; k y5g6v.bexvd)-fiqual?

(a) If two objects of h7oi.m0ln y-uqac 4*m different temperatures are placed in contact, will heat naturally flow from the object with higher intau* h4cn0.q iym7m ol-ernal 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 tropical plants grow but the temperature may drop bebv:b, bu1 xuj-kip,i.low freezing a few times in the winter, the destruction of sensitive plants due to freezingi.- vb1j,:u , pxbkuib can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes waterdi8i-ef3i7v n particularly i38d7 ievn-i fgood for heating systems (that is, hot-water radiators).

Why does water in a m u9sd 4aohj5v(etal canteen stay cooler if the cloth jacket surrounding the canteen is kept moist?ahv(o54 9 jsdu

Explain why burns caused by steam on the skin are often more severe t b1)t,3p:a9vezcvu vkya, a4nhan burns caused by w aa,ctkv4,n3p u z9ba)ev:yv1ater at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, r+rl7 szs 2ga3using the concepts of lateg +rs rsaz32l7nt heat and internal energy.

Will potatoes cook faster if the water is boilin1vtmu,sh5c5 oxa w82fg faster?

Does an ordinary electric fan cool the air? Why or why not? If not, xj9rp5)i 5.fi c hky)bwhy use it?

Very high in the Earth’s atmosphere, d-bqs) 2,:ff m nd:ndtm4*qbthw- 8bem9utz* 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 survived by comq . .8t dgtpdt2+oe6overing themselves with snow. W p.oqdtde6to8gmt2 +.hy would they do that?

Why is wet sand at the beach cooler to waq*9j/3fpo,.id 3b e-mqfew0g .ruv lhd wj9 0dlk on than dry sand?

If you hear that an object has “high heat content,” does that mepslsgz.3i* z: an that its temperature lz. *s:zgsi3p is high? Explain.

When hot-air furnaces are used to heat a house, why is it importanf1 8(o5hsnno wt that there be a vent for air to return to the fur5whs1fn n (8oonace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so t jpfisz6 sju)siu1716 hat they drive the air down in one season and pull it up in another season. Which way should you set the fan fo7 sj1 ij6s 1)zipu6usfr summer? For winter?

Down sleeping bags and parkas are often specifieq9fzo1/(*fk 27v jcur (1(oiwwwjp qud as so many inches or centimeters of loft, the actual thickness of the garment when it is flcfwr(1 jw*qq(z2u /1fiujkwo (7op v9 uffed up. Explain.

Microprocessor chips have a “heat sink” glu0k8d 0av* mvmyed on top that looks like a series of fins. Why dmv0am 8 yk*v0is it shaped like that?

Sea breezes are often encoedd l9r-k0u x 8wyrk301ildm2z0 zc 0zuntered on sunny days at the shore of a large body of water. Explain in light of the fact that the tempe2zkk00xzd1dl l uz3c -r09rydiew8 0mrature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can f w23djsgb l;.wlow is often cooler than a floor tha.b l;w2sd j3wgt 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 readingedr+zy/+ c*r(q q+haks are always taken with the thermometer in the shade. y+kq *de +/(qrhcrza+

A premature baby in an incubator can be dangerously cooled even when the 7t8sngco q;:)tpd: pr air temperature in 8q7gt)t :p;r:sdncop the incubator is warm. Explain.

Why is the liner of a thermos bottlegh1)wm c one1k7x 7(hh silvered (Fig. 14–15), and why does it have a vacuume hc7 x h)7ow1mhg(1nk between its two walls?

Imagine you have a wall that is very well insulatedbqfwjq/a -)r + — it has a very high thermal ba/)qq+-fr j wresistance, $R_1$ 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 procwd :+1kr(ksg: 1hbnr eesses: (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,wb +hkke nsdgr 11(:r: 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 f)zl 4otmjgx:vp82p; absorbs more heat than a piece of shiny metal. Yet the wood feelo 4l;) zjfvp8pgx2:m ts less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when )yn+zp(9a yon tscs2 vm-*vu6the weather is clear than when cloudy. t6)+ u aozsn9syvv(*c-yp2 m nWhy?

An “emergency blanket” is a thin shiny (metal coated) plastic foi4wobb 6x*+r zhks4r )xl. Explain how it can help to keep an im4r b*)w+xz hs4bxk6ro mobile person warm.

Explain why cities situated by thedfa zbf c7o9i htij0(/: t:p.fqn6q r+ ocean tend to have less extreme temperatures thzn:p0t+iiq dfj :q7h f .oc6f9(ab t/ran inland cities at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0 g4y7yr9vaun8yypeet xx r993 vx4xi/n6)- mgkg of water8vuyn9yx x)3i49yevtx9 4xmgp ae yr- 76ng/ r 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 thg 1 x 7b ga0o)etzbjtv-wkx(c7-b.a9wat is initially a .wx-xg ea9g)-ba7 koz0bw jt1( vb7tct 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 0yx/j xw1.;o:uhd2xq 02jch,r fxj ze 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 ofr60wm2vcfzps (/ uo/ y heat in the British system of units. One Btu is defined as the heat needed to r0 zm(u/6r/vp2 yfwco saise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generatzp oo7aa21u 6ee $32,000\,kJ/h$ 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. Estimav: d uv9afg2 g yzdox92h1y9,rte how long it will take to heat a cup of soup (assume this is 250 mL of water) fromx9 hv oy:y2 ,ag9ruzd1d2f9vg 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brafh(dq)yi mw zjm7: ( :fo*ama,kes are used to bring a 1200-kg car to rest f,:o ya)dzj qifwh:mf((a 7 m*mrom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16it(ujoe8xzl()s 7(0 1nr h fme L of water. How much heat does it absorb if its tempej1 sun)(f 8tmei o(x0hr(l ze7rature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat jgyvfs4f 7dc;b6 w,)eof a metal substance if 135 kJ of heat is needed to raise 5.1 e4s;67ycf jw ,fdv)gbkg 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 3oma7 uqwqid h6te;)j /;ki,3w q:r xhsame temperature rise when they absorb the same ixm eu7q:,)hiq3 o/wq 3whkrj6dat;; 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 thermometed f9)4b cpv1oaq/0x.ii./ hjgr jp)oe r 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 equilibriumw7; p;yq6jh;vtcv 1q t;tzh4z temperature 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 (t5g)-*8la hzf j ear ;8aldbo6mass = $0.4\,kg$) 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 to 3jab47ul, oxmi )d;4n6b2 :riwojx p:x30$^{\circ} C$ 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 cojj gj5g i8v/)+aub:x3(fnbi effeepot to bring to a boil 0.75 L of water initibjvabin+/: ()gj35eixf gj8ually 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 fro e +ymjc0/.n1gha-krx m the following measurements. A nay -ecj.x01 +gm/hr k15-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 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 at3wh6w ;o0.y jh sooow4 ipr.b8 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 sv(hd .t4f u7ihcp 6x .1zr4wzhas 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 ii)nuif:/s0q 68 ihj bbs defined as the amount of heat needed to raise ibbu0 )i ihni8f/qs6j: ts temperature by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melt 16.50 kg of silver that is x/;b no5du8 ciritr 72/q aw0kinitially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 452lctcoek/s0+ 2g kc8 s-m-high building. If 65% of the thermal energy produced when ick kct/l+2e 820sos cgt hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may giveav3 99yd0:fu m gu.t.)famfai off 180 kcal of heat in 30 min by evaporation of water from the skin0ff. 3y9a mfv 9tuda.:gu)ai m. 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 por.z/j m2ja3/9e * z- u4ypyqvdpa- dwlint is dropped into an insulated container of liquid nitry ajaw/.pe4 v*u9--lzmpjzd/ yq23rdogen. How much nitrogen evaporates 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+60yj2ki dl7ntpys - y freezer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass ns:w848cc icw 230 kg 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 bicyclist consumes 8.0 L of water over the spatet: xjh/aa*id9 4x4 dn of four hours. Making the approximxt/ex: dt*dja4h 4i9 aation 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 atvw 1o 6.o8/ kb;w)7vpzolliyf 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 me-su/3qzz5k7p x. xyokt u68 mtdug2i :rcury is $138\,J/kg$$\cdot\,C$ Determine the latent heat of fusion of mercury using the following calorimeter data: 1.00 kg of solid Hg at its melting point of -3.9$^{\circ} C$ is placed in a 0.620-kg aluminum calorimeter with 0.400 kg of water at 12.80$^{\circ} C$ ; the resulting equilibrium temperature is 5.06$^{\circ} C$ .    $ \times10^{ 4}$ J/kg

  A 70-g bullet traveling)i1pm5:et cpf5p-fii c 3 b8nf 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 movqgfrlfjb e 3);m4nkz4 j *5o)3z*)xkg yl rr3xing at $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic investigator notes that t hp h02c*wgxah ;ox4 bz,2vg,ghe 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fired at g4a h *,;2xcv gohp,02wzxbhgroom 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 2gq-y8rx9eu6ldex1u(/ d pfk aluminum 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 conduction in Example 14–10, assud ibk2dgbzls0t*,8j. ming that there are strong gusty winds and the external tempetskzbb g02.dlij*,d 8rature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivitz79s.ov ue;dry $e\,=\,0.35$) 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 i(53 : ao:thk3kerxrj flows by conduction from the blood capillaries beneath the skin to the body’s sur(:hkrjex a 3or3i:kt 5face 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. Bej+ 5b3nqpge :mcause of a numbermqp+3 ng 5:ejb of 100-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 Sump/ a mr6h6ux3n to melt 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 cross-sectional area .)wl8qh6vyr nr0yy,:j x5 e glare attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a conhw8nv:r yry.yl5 6e 0lq,x)jgstant 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 pr2; wtzu.n)g7v)c az the rate at which the whole Earth receives energy from wc 7ztv;2unp) )azr. gthe 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 is75hztizbimy7p 2 o :.s dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in tep.57 z 2st7ih:bmioy zmperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of+bb h*vks.ir 0q-,w ek the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat losk ehqv-+*.,wibsrk0 b s through such a wall, if its total area is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separated by an air spac blf6471s j3gv/qnp w+ mtzr6ce, Fig. 14–20. (a) Sh pg6n +jlq/vr4zc b mfts1367wow that the rate of heat flow 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 lon,t8lnu mt)08iy (5t mert rtz1g should it 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 of lxt 1 3v) c;5)xukbcvrsiquid 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 contain.mw.zmw0( gm v/t+m,abxej1ck sz 9)o ed in the world’s oceans, estimate the heat liberated/ weaws(m ,ovk x9z. .0z+tmmgj1bcm) when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed blockmn,:o a9vxjl8deqqr8 6up3qu,ff z2+ of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.02qmu v f,flq8jrn23 8,9:d+opzqaxeu 6 0 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into bc 7 s.* )aer*iwrbn3 kxve9;kspace by the Sun, assuming it to be a perfec.wexvn3 *resc)7kk*rb a;b9it emitter 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 xmfry1 d+g8ytd(yf 9/ 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 top of a cliff and falls a verticapfhlf7.tkq4o gg2ti )k5x3t; l height of 140 m before striking the ground. Estimate the temperature risei7 g.tl;qtx3ko p2 fkg5ht) f4 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 inw ,-id7s(sojaitially at 20.- a,7(jswods i0$^{\circ} C$. 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 jacds,)df2 mj4dv- f: :badz d:pvket 3.5 cm thick with total surface area jd4)szv: , d:-fd df amvd2:pb$1.2\,m^2$ 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 meth 8)1 y;msrgiqabolism 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 whllt3gr-/c ms 9e * yam15rs ,t)egxw;cich heat can be conducted from the interior of the body to the surface. Assume tha*c twe)mc9mgx-r5;1y/sletg a ,r 3slt the thickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thick (assume conductivity of air) 2a zm6znb * y+p8mi)u0j;cao sand are n2zy m;6j op*b)mcia80asz+ua $410\,m^2$ 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 tran dd* -tph akrxda):+;veling 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, sf n,n7s 2 wla1cqq;5btake into account radiation from the leaf to calculate how much water must be t,q51fbla7n2 snc ;ws qranspired (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.nd /ss-q0e : 693cjtt+fw dxgp If its initial temperature0fqp /6dg:x9sewcttsd3j- n+ 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 4m6)r1 nlcmta 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 jdil9+vwz.sf y; 06wn people hit a soft rubber ball at a w;s yjl+n9wf60w idz .vall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the finstfas* :, gmi0pv7o69 pdi4tual result 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 lose5;6t6 hd c8m ,; xujvazijj*izid:p 1c heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take fix;t*66d1jdzijc a hj,:5; p imvzc8uor 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 hoji)wi7+b giha- x v)p6cf;4dishwashing, there is “no hot water” left in the 50-gal (185-L) water heater. Tgac7)f)i+v px h -w 6jhb4ioi;his 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 f)*f/q bma ;-6 jglzm5cb)kpv 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.    $^{\circ} C$