What happens to the work done when a jar of orange j .qydwu kccmq*/2r 7n9mva5 kiv*(b4wuice is vigorously shaken?

When a hot object warms a cooler object, does tek-2zqc/3y5aj/iqp 7g; tc(ubj kab2 c mperature flow between them? Are the temperat t i5c-2g zk 2 jkj73q/bcbcaayuq/(p;ure changes of the two objects equal?

(a) If two objects of different temperatures are placed n0q v7vreda;v000 m; rpaw0e xin contact, will 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? Exprqe00vneaav00 0; 7 d vxwmp;rlain.

In warm regions where tropical plants grow but the temperature may drop m +y8 g/ 1f8qbqh7fjvmbelow freezing a few times in the winter, the destruction 1hbjmq /fgm8qfv+8y7of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. 5(1ym6sno jr vrq i+h: bd.n djt*j9*kExplain why this fact makes water particularly good for heating systems (that is, hot-water ra 5(j.y*j:r1+*jmnshq9dk 6 rnt obvi ddiators).

Why does water in a metal canteen stay cooler if the cloth jacket s k(ynrv8d.sa,urrounding the canteen is kept m8.(ydr ,v kansoist?

Explain why burns caused by steam on the skin are hu/rlw kvc*09 often more severe than burns caused by water at 10u*hvk /rl0cw 90 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the cdc+t*cne7pd a2m) pa ,oncepts of latent heat anccmd* naed +72ta, pp)d internal energy.

Will potatoes cook faster if the water iub sfqwplv7gk) potk2/4(4 a4s boiling faster?

Does an ordinary electric fan coola+r- h.kol1np the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature ca 0p5v/ yo)ubr2*dtj phn be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expedition r0d9aao/xyf 8s have survived by covering themselves with snow. Why w/a9o8f0 dr yaxould they do that?

Why is wet sand at the be:, ;(jblvnpmp5ass*57z1vse l5 b zvhach cooler to walk on than dry sand?

If you hear that an object has “3.me gut wyp0mw:r(p (kxi2a4 high heat content,” does that mean that its temperature is high? E g umwpre :.w(xp0y ima(tk432xplain.

When hot-air furnaces are used to heat a house, why is it important that tw fv ir+ ;9.,t-7bddiufdd hq)here be a vent for air to return to the furnace? What happens if this vent ihw)-idut9,v;7 .f i rf d+bqdds blocked by a bookcase?

Ceiling fans are sometimes reverssdci 1t wfeo o62*.i:rible, 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 fw 2i.eo:do 1*s crti6summer? For winter?

Down sleeping bags and parkas are often specifuz0a mln*k(8w(i l6ubied as so many inches or centimeters of loft, the a8ukm*(inu6lbwl( 0z a ctual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that ljs9g ;x;rshh, 9 oiyg8ooks like a series of finsjsg; hg8hi;osy 9xr9 ,. Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shor. wtu-u0hu1a fe of a large body of water. Explain in light of the fact that the temperature uuwh u f0ta-1.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 flow is oyq*1*o6 yv/v 4rm rnzuften cooler tharu/ 1ry yvzmn6o4**qvn a floor that 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 ( p uc aoga4c4oz3;0taxhyf/u3y(-jyq 9 +ssjalways taken with the thermometer in the shadecgox9sf(yu3 oza04/sy ujy+a3 j; -qatp(h4 c.

A premature baby in an incubator can be dangerously cooled even when x kp+nq9n *p8ethe air tempp8x9epn n*+k qerature in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered ( e66iva1f uumh+nc-uy0 s98keFig. 14–15), and why does it have a vacuum be6s+nf8av-u u 1u6ece 90ky himtween its two walls?

Imagine you have a wall that is very well insulated — it has a very high thermalmkq1k,a 0z:f2 mxh s1pwc b.f3 resistancp3 2kqz,amfb0 fws1 :1 hckx.me, $R_1$ Now you place a window in the wall that has a relatively low R-value, $R_2$ What has happened to the overall R-value of the wall plus window, compared to $R_1$ and $R_2$ [Hint: The temperature difference across the wall is still the same everywhere.]

Heat loss occurs through windows by the following processes: (1) ventilation ar1rrn4x6 eugqba6k ;-ldk7 cm4ound 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 ccg6r a44xenr q6kluk;d7b -m1urtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piwn (nl4:v)hmbzy.0sjii f41bece of shiny metal. Yet the s yhi4l nwnj b4f)( i.m:vz01bwood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when u7qpr .o.0c3 yztli3hf3kjo9sdhjq65f m-2rthe weather is clear than when clou-cjhuto qf yj3.6orq03smki. 2z7dr3l59f ph dy. Why?

An “emergency blanket” is a thin xy(p l;+w4) owxm0ezbjk1kz /shiny (metal coated) plastic foil. Explain how it can help to zw+w4 y/o xk)jxp (ebl1mzk;0keep an immobile person warm.

Explain why cities situated byxo34z,raz)+i v1p e60sn qkqt the ocean tend to have less extreme temperatures than inland cities at the same latituzi,6ns0q o +) 3za4pqter v1kxde.

  How much heat (in joules) is required tomyp;dd345c1 quf k lh; raise the temperature of 30.0 kg of water from f ;lp5umqd1 yh34;dck15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of p h;vb *pk3w;vfrgjyx(; + u2wal7i b.2 e0qieheat raise 3.0 kg of water that is initially at 10.pbu.e2(vvi2+ g 7l*w;w xb phk3yf0j;a; rqei 0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cals*rh7j ;jz6zo djm kc++ r3w69kf,w pq 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 heat9ix2 u9fn2zkpc9m jx9 in the British system of units. One Btu is defined as the heat needed to9km9fxpujzci29xn 9 2 raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gene9 b6j5ovarsg1; sc7 cb21kf imrate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is ray7;uyvmfd;a u2c6 us,ted at 350 W. Estimate how long it will take to heat a cup of soup (assume this is 250 mL c7y2vu; dmfsu6ya ; u,of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocaloriesmf// e.ua0iyp9(vp)f:dn lae are generated when the brakes are used to bring a 1200-kg car t.p(f f9maiua pn //lv:dy)0e eo rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does ilqb)p,*z+t.if,v,a7 wb f joet absorb if ittvwff,7bo )+*lp j.aiezqb,, s temperature rises 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 needty4 d5ja .li/0uo, osved to raise, y o4s/voudja.i05lt 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experienc+;a wx3idrse 5e the same temperature rise when they absorb the same amount of heat. What is the ratio of their massesx+das irew5;3 ? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21abhn+ pp d m/w d;v/)q2b.we8t.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 temperatuhtzjwl,-k1yae vq0w 1 .-xux/re 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 horseshoe7 w 48k jxl c+7bg-9tjuw uu4)yb4dstt (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 is heate*2n*4beq-kff -biyjl ,a fkwa;vr6 p -d 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 ofwzrv+)dfa o4qlq3 s0 40,yb1 .tbnqje water initially aqn .ya)vqbz0 tslj1doe+w4 34b,0 qfrt 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 fl6 zjn,a3,e j7ntbm- sollowing measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup ofn3sbj z, tm6n a7-,elj 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 at 1h0 oq9p+hxl tz/l-d z,80$^{\circ} C$ 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 h olb0 92j*xeuuas 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 jn26z, cfl u:kvako.4l:n+-gb wxa7 zthe amount of heat needed to rai.j7:kzg:6aa ,of cvk l2l z+wub4n xn-se its 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 in aceo.am-x kafi1s69/f n8h (uitially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sph) ht.8x3w nlrmere is dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbedw.8rlmt hn 3)x by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may git / zwezuo8vin k6,k 8fj8p5lxg) zr40ve off 180 kcal of heat in 30 min by evaporation of water from jgxr/k 8088 v znue5l)46,tofzzwki pthe 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 insulateh-4) fkjfyal c 9fyra4g pb-:.d container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling pointyyljfp-4.)c:a4fr- g 9b fkah 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 freezerw.xytbdinf8 *xaq +i+b/s. t( 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 230 kg containsg(qat hm 6(f*sek lw06z n1lziy5)1cn 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 8uf+)hd kb:: zx:y* vny.0 L of water over the span of four hours. Making the appd:*zvxnb:yk: )y+fuh roximation 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 a* ho2 iu9n xzi;v8p yclm+fq;*)ew 8got 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 is f* smrnkcp)jhqgca-9 64*ge , $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 akf+ 4)r: qhzgrt $250\,m/s$ 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 at u oc)z74tlq0o $6.4\,m/s$ 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 forensich1pgadrck ;e0n2k9 (s investigator notes that the 8.2-g lead bullet that was stopped in a door 1cn(g pr9k2k0hesad;frame 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 aluminui-fo70u m6 i0hlsl gt:m 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 fq 6*bsa o(k-;+iu*f:cw hwwjtlow by conduction in Example 14–10, assuming that there are strong gusty winds and the external *ww*-bwsj+ actkh6; u iq:f(otemperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivityxi8da wtqhrrj3r))7pec-z6 1 ,* nyy5zblpj 6 $e\,=\,0.35$) 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 flq.ss koy 8z4( (k)p1 zjh7xytcows by conduction from the blood capillaries beneath the skin to the body’s surface area c k)41 psoy7xyz.(tz j8s(qhk 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 s mtmg2;lwv59:(y pub gide, share a 12-cm-thick brick wall. Because of a number2ml( twpgmv :y5;u9gb 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 Sun to melt a block of ice gnc,j- l+x:vai2 nwx 3wpr)w: 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 a pga*qo8ry5) r7ui(iz re attache75ior)*q yuz8piagr( d end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estim2j 4/bx;3c mrots6 eruml75ta ate the rate at which the whole Earth receives et3boe r acjm;6slrx/45tum 72nergy 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:jq ds:vibs 92 W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What isvqbj :9:is d2s the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mmcuvo /s ,4z.hainly 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 loss through suchh/zc, u v4ms.o 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 ha8yn 5m rfkeg 93yeos67s two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a windnesmegr386 f 7 5yo9ykow 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 shvz;q pfphkwxq.; 1i :hu2.p 4iould 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 liquid a4xb1zsy4 rml.w +7pk 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 worj9-ddzt 0 g-ytvb9fn *ld’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate ty9d9t-jdv nf*b0z g- the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by c smq,vuq2,:w firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has bee ucqv,msq,2 :wn 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,z;nn fg9zfle27n3vh: 1ka 3vr assuming it to be a perfect emitgf 1rhn;v az 2z7v9nfl3 nk:3eter 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 activitvl(uevo.z1 p+6y7tibcehr )3w )f7dey, a 70-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( 1bq0rgi (ul 4q-blof the top of a cliff and falls a vertical height of 140 m before striking 1g-0o(fq(lbb4i u rqlthe 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 pa,1ppxe5n rn xi)a 1x n seeo)z/*9gu9hil of water initially at 20.a1pxei, 9ueh )zgo) rnx19pne5n *xs/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 jackkj+:+mo d5uuq et 3.5 cm thick with total surface areq+ou:d 5kmu+j a $1.2\,m^2$ 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 metabolivvi,4of67q/ v bny 7wtzi(ke.sm 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 condu2kfdc3u+v(u qe j s1os-ud/, qcted from the interior of the body to theu,q23+1dkc veuu /ss(j do-qf surface. Assume that the thickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walo0pqrg(ww a 20ls 17.5 cm thick (assume conductivity of air) and ar0qa(0w 2gr wopea $410\,m^2$ 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 trav/0 bvjoxrx7 f8c nw.w6a4l52 vt j0idleling 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 arum mjlu)55 5account radiation from the leaf to cau5 mu5mjr5a) llculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts to4s-37a xbe1 bll(zg when it enters the Earth’s atmosphere. If its initial tempera lglb7 x( bst1e3oaz4-ture 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 c8o2qla qh+*t+haglb oag.s44 0s juv.rust 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 5a ncv-8l0(*5 z3rfbpfvl lwa(Fig. 14–22), two people hit a soft rubber ball at a wall until nv vlfc50(aw5f llp8 b-za*r3 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 final result when k3d 6d64ooyirxzv l2 8equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and radiation anvo(a u.-w e9ct a rate of about 200 W. Estimate how long it would take for the body temperature to drop fa-(vn. cwu o9erom 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 dishwas)mq;7 sps. w7k+nj5uvekz2dw hing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water .)uzjns+v 5mse7wk2 7 qkdp ;wat 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 surfb,d+z. tw yu-. pu6tcxace 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.    $^{\circ} C$