What happens to the work donen+eay- bq,*mm when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow betweeny nc4nkz:.0y78ni .ln jq,ice them? Are the temperatuj .nlni8q c4zienyy. :c,0kn7 re changes of the two objects equal?

(a) If two objects of different temperatures are placed in co +i::pu(lxrg dntact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for hr:: pxl(idug +eat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the tempet( 4;eemw2n. w(q ytkirature may drop below freezing a few times in the winter2qe(( ew tn.wi yt4;mk, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is z/ k+if*jx1g9pxvg2 rquite large. Explain why this fact makes water particularly good for heating systems (that is, hot-wategz91 xjx2rpfgik /v*+ r radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surrounding t)4ehx 2 q*a4e27t qpn6g yh-sgmxty3uhe cqg t*4xex2es-p4q7 y36mhhu2tay)g nanteen is kept moist?

Explain why burns caused by steam on the skin are often more severeuy/o;3b9nh) 4 wdi(wkdhg:pj than burns caused by water at 1:dkw9huw ph 4;yn(/ob )d3ijg 00 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the(j rs7osj9vf tm/ h: ( fkzcvo+fc*,t+ concepts o+o h 9otsrj(skv , (f*/+z7cjt:ffmvcf latent heat and internal energy.

Will potatoes cook faster if the :2u +s okuz7/qv,kom cwater is boiling faster?

Does an ordinary electricgwi0atj 6zsky5s05c + +fq-u x fan cool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, thq71+3ova nsb le temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arcti ;./ikz-oluw; gntx3z c;h7 avc expeditions have survived by covering themselves with snow. Why would they do t ;g.han3;lto- 7zu ; kziv/xcwhat?

Why is wet sand at the beach cooler to walk on t q hrlx8v9:u15 hkizk2han dry sand?

If you hear that an object has “high heat contentl 3dzml m+4cosatmp no-of69-a*g -3k ,” does that mean that its temperature is high? Explaioo a pc-l-knm-9g d3m34fm6+ szot*la n.

When hot-air furnaces are used to heat a house, why is it important that ther oghr3qr (eq*sty g5/j63f:k -s tq)xpe be a vent for air to return to the furnace? What happens if txy : s)qep*tq5(3/gh6j3 qtfsrrkg- ohis vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive tho+1p4, wug um 3z;6cm hqlemv:e air down in one season and pull it up in another season. Which way should you set the fan for summer? For wintegc zoeq1, w6u+p3; :mmmu4vhlr?

Down sleeping bags and,v1a lstm4ysrmz r;/, parkas are often specified as so many inches or centimeters of loftr,rzlms4;, symtva / 1, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top blka4a91g /fm:xl8b nthat looks like a series of fins. Why is ita/n8xfb9lal1 : km4bg shaped like that?

Sea breezes are often encountered on sunjk):lp888 ghz.5ki ;tw om/xwe.fzng ny days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the nean.5;hzizkmpf/gw8 t lx8wejg. o8k:)rby water.

The floor of a house on a foundation tu 5jytxx0b8x. ,et2a9l kv: gunder which the air can flow is often cooler than a floor that rests directly on the ground (stvklt2x u y, ajtx98x50e:gb.uch 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 temperatur49o3b)jjh pqdv:a1 ote readings are always taken with the thermometer in the shad jb)vdj9qh:4oa3 1ot pe.

A premature baby in an incubat )fgqj/q4 6px*qmtiwo f9 2jp4or can be dangerously cooled even when the air temperature in the incubator is warm. Expl4 wg f29jmj*6px4qq/ofqpt i )ain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), an ynv1,tk , jsd8f9 ayzc)msq38g f-ja0d why does it have a vacuum1kgcvaq yfzfsd8n,jmsy 0j ,9 3at-8) between its two walls?

Imagine you have a wall that is very well insulated — it has a very higbifi;nr8b v yi.6p-u dirt74/h thermal resii.b 6 /bvrni-r4y 8;tif i7pudstance, $R_1$ 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) v 91amvy 0-t7idkul,xm entilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass i-a9x ,7ymukdlt v0m 1panes; 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 detail.

A piece of wood lying in the Sun absorbs more heat taixf+yaee*.u*7: eim 8 1zsn bhan a piece of shiny metal. Yet the wood feels less hotane1x8u *i.7aez m+:i ys*fbe than the metal when you pick it up. Explain.

The Earth cools off at night munvel / d xidpwg0uy:.a-8n86;zm8 kffch more quickly when the weather is clear than when cloud /:gfdf8;lu mnydi6- x8nw0p.zk 8aevy. Why?

An “emergency blanket” is a thin shiny (metal coated) pl;v4(wm zbs* kgastic foil. Explain how it can help to keep an immobzb*(ms w 4k;vgile person warm.

Explain why cities situated by the ocean tend to have less 6l/ qj f,jsmjxb)41mqextreme temperatures than inland cities at the same latit/j)qq m m61,fxl4 bsjjude.

  How much heat (in joules) is required to raise the temperature of 30*l*;o 2fgn,z dxt/jz/zwo rq..0 kg of water froto/zw*zglnq xdf zo;*r /,j2.m 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J ofg*x bhbhau3k;d mp, rx8w8rfyr)09d( heat raise 3.0 kg of water that is initially af , b wkm9( g3; a0r)*u88hdbyxrhpdxrt 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 ati6qe :x tc3vzd1p;2Cal 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 ts )z+eu2qb kht.jq 0 r8lbv+f*akh8y:he British system of units. One Btu is defined as the heat needed to raise hq)r8 ysk*q2zbutehva8j+ bl0:f + k.1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can ge 2bheqrau3* 5ce(no- snerate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated at 350 W. Estimate how long it will 2sbfor ;vh)x78i7l1jg wa0 oh take to heat a cup of soup (assume this vgobhsx rl7awj)07h i28 ; 1ofis 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories areoze: r.8a j7nz generated when the brakes are used to bring a 1200-kg cz j:eraonz 8.7ar to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L o.sk b7pl)/aqp.a h+quf water. How much heat does it absorb if its temperature rises from 2 +q)lp7/b ua.aqps.hk0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substasgnkxb. 0ecyf 75qna2c:7u6 x v: ol+ance if 135 kJ of heat is needed to raise 5.1 kg of the mecxesa+gk 0 v5xbfa 7y2qo:c7l .:u nn6tal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature risegza1sfr ub7no;2s-hjc8v 8 2u when they absorb the same amount of heat.jncza2; bu 7 u281-osvgs fhr8 What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21. dmc (m/c;ap4e6$^{\circ} C$ 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,8tawze8a (cij5g*: x*dhw ic block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (mass =7lkk ebt2 y5evuxvld3g:-w 4v,t)e1r $0.4\,kg$) 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 toju, ja7wk42yg1uos (t 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 ol+gy xtyk zjpw-h18 ,/jjk::lf water initial-k l z,:tly gj8jwyhx/j1+p:kly 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 bi g,bly71 gasxcsx-;:pej.;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 of mass,. l ig ;x-;:bsc1axpgbje y7s 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 a.u9 zy/syod k,t 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 h b73 cyru8mh8 zh5nm:xammer 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 (rv31wxam d m2ra( /rxamount of heat needed to raise its t / r rm2x(rw1(avmdx3aemperature 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 initiad2cxsy yj -5-hlly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped frc -kfqf+:qooz 88hg5jom the roof of a 45-m-high building. If 65% of the thermal enerfhk o8q: qzjgcf 5-+8ogy 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 evaporrq.t t17sy3ki ation of water from the skin. How much water has been lot7ry sqt i1.k3st?    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 contrjio wi9u t ;f :.pqh(83li1itainer of liquid nitrogen. How much nitrogen evaporates il8.3h;p qti9iftiuor w: j(1if it is at its boiling point of 77 K and has a latent heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the freezer sz /fvekvlve 3 8yr5,w49kg 4t,j k)osat -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 830 kg of water at 18mz+ qv6:gp*e l u9fc8b$^{\circ} C$. 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,sid4g1 6j0yb6qtmh /o a bicyclist consumes 8.0 L of water over the span of four hours. Making the approximation that all of the6hos0d ymg1t4ji/ bq6 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 at 100rw)-qu2g*r5l0n veq d$^{\circ} C$ 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 memyp2csx-u74mb05 t5swc;rec v p 7te ;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 at .h4ndpf bi h c7g1d6c,$250\,m/s$ 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 movilvfevy 9sb *;lhb81m 0ng 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 investigattjf/tr::r/*q c4hpq for notes that the 8.2-g lead bullet that was stopped in a doorframe apparqrr qj/ /:c4t p*ft:fhently 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-lyqc:yd 8e3.y xb w,-ucpgg.5jt z6d 6gong 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, assum zo 055pw0qexnhdz 08xww h -(oi5ek9wing that there are strong gwzd5x xne9q0-( powi8 wk e0w55o0h zhusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungstenetwuw- g e.ev b+l4y*tdb .i2, sphere (emissivity $e\,=\,0.35$) 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 hgsq (ua p.6*ju)hb nh 62tb(:g/lb 4efk9yfpaeat flows by conduction from the blood capillaries beneath the skin to the body’s surface area of ptb4fl(fg9:ka6)sg/ h* ( e u6. bjbu yqapn2h$1.5\,m^2$ 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 sbhv (8:2izz4r 7k3cxbnz fl)hide, share a 12-cm-thick brick wall. Because of a number o(3l2 ic8k4f)hvz b:nb zhxz7rf 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 sdvn*(* nihcbmy y0.(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 a4s2x0u uhm+8zce rqa .luminum rod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant tem02ur+8s.uecqmz 4 axh perature 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 ob*kd+ ,q* cokthe whole Earth receives ook*q+k ,bc d*energy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of hef ,xhf z9:hjhui jxergb0,19 (at, which is dissipated 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 anr, j:i(jf,xx f10h9b uh9gzhed outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualo7k: jpuocn+2 ities of the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, a7j2okun +po: cs 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 an air/. 3x9cyq;chshuh gs/m l j/qnm n5+p. space, Fig. 14–20. (a) Show that the rate of heat fl cm3/x; qhc+/.y/sjlhhnnmq 5pu.9gs ow 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 kg of ice at tk2rqf2 8hrp ypp(i, -b1u: k8j rf;bw0$^{\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 at mr k:3pn 6czs0ymj /ore8z - 8)0xshqf5$^{\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 energ, 0ibe* wni8bt tqi0,b6i:z ycy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water iwi0,i btnbie:c*08 yz qbt,6for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wood witc0r to rxxn2*2h a mass of 1.05 kg. The block and imbedded bullet together absorb all thx2* rro2tc0nx e heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assumingjx.q7d7c8w reo,v )jc ,asud5 it to be a perfect emitt)uq cr s7 7.cw,ae8ddxj,o5jver 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;8hg 9fn)jn2cvwt0lt5xl( 6t9 w5hsi vvn p,k 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 .x5wm ook arv: ;bhy35rolls off the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temp w3obxoyrhma : k5;v5.erature 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 r /8gtiv,zc8 pa 2.5-L insulated pail of water initially at ,pvgi/z 8 t8rc20.0$^{\circ} C$. 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 ard7apw4) ww )k)zd ve oe6ym(ai7)w; 3.5 cm thick with total surface are ;e7)idw4y)oa)7 az(d6)wamkprewv w 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 haspwqtwo6 2 3yo 5jkm/5i an average 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 yp8wixb;v z:4a69on ija0e-r conducted from the interior of the body top e aj4o :ia9- 8rx0vi6z;bynw the 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 walls 17.5 cm thick (aeupon +z4vdi s-p7t -3s59sesssume conductivity of air) and areaeuz e+ ptv3 ds-ps s4oin795s- $410\,m^2$ 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 traveling a/tta v h0ql:5vt $220\,m/s$ 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 radiation from t 6z0axju(iwiri8utc3ig 3) * yhe leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35rc(6j3i3ti8iu z0i )xyaw *gu$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its initial teo:t -0fbu 40alk)4ecvyg5bf kmperature was -12uf t ay4cb:040 gkle)obf5 vk-5$^{\circ} C$ 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 increasess.+(hq*q eabc 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 soft rubber babn,nl hcmgonh)8cqw ;2h i(n .30e 4vgll at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall a3mhe bn4oqn(2vhgh)c ,.; nlg w8nic 0t 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 equ)zihzcpt*y y2;rkx z4olz9(n ni 3 3;aal 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/uqma 3v+u)02ebuvh x radiation at a rate of about 200 W. Estimate how ux20uq )mveb uv a/3h+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 la8-8uy8tdqg, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with wate qlgu-a8td8y8 r 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 s sszr7:kt2h g (bw p*spm78y5lpbo4 d1urface 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.    $^{\circ} C$