What happens to the work done he 0z ul0 sgoat:;*qi;when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? Are im+ c 78oq+uuw*nhf bz(ren65 the temperature changes of the two objects equaz5ou6+7*+ i8 m ecfuwnr b(nqhl?

(a) If two objects of different temperatures are placed in contact, will heat n m gb8j6h/frjk20;ognaturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow gg8b0/kr jh2;o6jnf meven if the internal energies of the two objects are the same? Explain.

In warm regions where tropicaswf*2 lm1;szel plants grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plant* ;1s2sm zewfls due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain x(0 8 xuvk g,l;cvy.bsr6 aujp2s)u-b why this fact makes water particularly good for heating systems (that is8uvx.6csbsb,xg;py uv aj20)(rk -ul , hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jace(djcai.9 gu(z9 lt/h y3ua5kket surrounding the canteen is kept moistaut.39(kuay (jce5g9lid /zh ?

Explain why burns caused by steam on the skin are often more severe thamm/cao w)met+z-6 gwo+ p4pzv-yz6+t n burns caused by wa4w oepp+-o/mc-g6wmt+z)y v6ztam z+ ter at 100 $^{\circ} C$ .

Explain why water cools (its temperature ywk nf: e ztw;afw am( )r69kfk(p71q:x6w8p edrops) when it evaporates, using the concepts of la96 wqf7pnk fee ktfw6 :p xma:;w kw)1a8ry((ztent heat and internal energy.

Will potatoes cook faster if the 7poe0*te ,z lsj.juu oyo93 d2water is boiling faster?

Does an ordinary electric fan cool the air? Why or w611dhq gu-tff 0twrn.5pms. khy not? If not, why use it?

Very high in the Earth’s 09 zi(x;s rp4xsrg9vj atmosphere, 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 covering xa-i wj+.+ zgithemselves with snow. W-.wxij+ga i+z hy would they do that?

Why is wet sand at the beach cooler to walk on tha;, 3eo,:rfj)wdlo hlfn dry sand?

If you hear that an object has “high heat content,” does bakjl3t9y6mxe, yexh5 h 45f0that mean that its temperature is high? Explaxf x j,btk53h y0ehy65lm94e ain.

When hot-air furnaces are used to heat a house, why is it importanbayq/w*grj x 174r0ojt that there be a04byr axo/q wg j17r*j vent for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the vh7 zcu8u1sr e66d0; d2xums(qp0yqnair down in one season and pull it up in another season. Which way shon0z(hd2 red0ysmp7quvuq ;u xc 86s61uld you set the fan for summer? For winter?

Down sleeping bags and parkas are often specifr-umcq ja+8n m1ij, e7ied as so many inches or centimeters of loft, c,mq+ji 8 17m auenrj-the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “he77 ryj8w* hqd,vagv9dat sink” glued on top that looks like a series of fins. Why is it shaped like that*vvr,gjh 97da7qyd8w?

Sea breezes are often encountered m :faiqtefyy:0 z hk5d:ou ,top25h0(on sunny days at the shore of a large body of water. Explain in lightf20u: : pmhdoh:5zqteotf, i(0a5 yky of the fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a f q1.m p ..d team45aqzadlis1*oundation under which the air can flow is often cooler than a floor that rests directly on the groundld q 5sdtaqmi1* ap.1.a4.ezm (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 s yu/4i*6aq vpalways taken with the thermometer in the shade./p64yiqva * us

A premature baby in an incubator can be d,(bp,ov,gu9 xcx:nd dangerously cooled even when the air temperature in u,x db,(g9n :pdvocx,the incubator is warm. Explain.

Why is the liner of a thermos brg ucb/29h+d3go xvhy5rmwu xi4+ 2 o2ottle silvered (Fig. 14–15), and why does it have a vacuxc4xo+r u/52hr gbig2dm wo 2uvy9 +3hum between its two walls?

Imagine you have a wall that is very wel 0b; ujmngr3j4/1ln3c:vv mz al insulated — it has a very high thermal resistance,/l 3;jn3 1vj:bzuac4vgmr m n0 $R_1$ 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) ventilayu*h5d(9n d8 9 )vcsr6xo eqaltion 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 medh( dxs596 o)nc 8aqruv9yl* echanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying+mrq/u hp52co in the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot th+ 25ocu rqp/mhan the metal when you pick it up. Explain.

The Earth cools off at night much morei :4e2d3.j g d h:r,u5fouyadl quickly when the weather is clear than when5y i :je3f:d,4 .lh2ugau rddo cloudy. Why?

An “emergency blanket” is a thin shiny (metal +u;ngy5 t5u7q wvvy 4f )zke6mcoated) plastic foil. Explain how itw756y5tzyu+; em vf nu4k)qvg can help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extrhady39a/ibh zi4 mz,( eme temperatures than inland cities at9z ma(ayiiz4dh,bh3 / the same latitude.

  How much heat (in joules) is required to rai5drbqueh9c nm3 )b3 0wse the temperature of 30.0 kg of water from 15 m d9 uc nq)5b0w3br3eh$^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is initially y)i lxbr.v3c5 at 10.0lciy5x. )3r bv $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes abmw2 9e;jzzlx 15a9j-hyc7cv tout 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 uniqjyweo 3p( .s/t (Btu) is a unit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lb of watp y.(eojsw/3qer by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genedriys+so7, w0 rate $32,000\,kJ/h$ 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. Estimatet*kjk8 y,nvgo9; )tcq how long it will take to heat a cup of soup (assume this*o g 9tv8tc)nk ;q,kjy is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generax5l+1x22 xtzq +qjos sted when the brakes are used to bring a 1200-kg car to re52z xsq+ +jqx2xls1to st from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 q 9rbfy1j idli a)823con1vd :L of water. How much heat does it absorb if its temperature rises from 2f83dq il )c: 9vdi1 aobyn2j1r0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat nc*nldt,h9o 0 of a metal substance if 135 kJ of heat is needed to raise 5.1 kgn0 lnh9d,c *to of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and wate2 jcqq zgcs.87r experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hin qg.qscc8zj27t: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 2+y4vcgy cf n1:jogi9: 1.6$^{\circ} C$ 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 24+nqu a7xj kg..e fig((5-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 (masws5h+8tsp vb1 i)xmy7 s = $0.4\,kg$) 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 heatwsq1p6fo3 .hv4jw j y 0hi2v+ped 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 jrjkos 6, ydxs:;r9.r7ptnj /bring to a boil 0.75 L of water initially n;97.ojdr,/prr x6 st:sjkyj 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 fau4vfm+ + 8q nfub.vw1el3 zyne6+ bd8rom the following 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 0.624 kg. The initial temperature of the mix +ae.wy +mb4+nev6 3 8uf8qf1blzdun vture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of ironlzt)lon9-u o ) at 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 hammerhwka )5 1zfv3n 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 needed to ze vwqc4su79:/uz6wcraise its temperatu q6wzs: wzv9u/u4cec7re 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 kgoc1bql9sl: x5 of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high buil9gr;9qha 4fasding. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase? 9 9grq4sa;ahf    $C^{\circ}$

  During exercise, a perso 0yc2 b9 fnzjgxkave ,ue/n1;c,fnc6:n may give off 180 kcal of heat in 30 min by evaporation of water from the skib n9 ngufn,vc;e: 0e21,z/kj 6f cayxcn. 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 mernar 745 6l45(fu(ovshkurtek vy3- hlting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaptn3 v7r(ou 4akeh 5- lr6kh5fysrvu4(orization 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 fr8g oc+;mu+cz.-cvcd bmo -p s7eezer 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 cont-d a/2l,pjol 9ac) h si3.k djj7bl10qaz2jqkains 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 0 .d lo6 kfat5z:wg3 mtr/1bsy8.0 L of water over the span of four hours. Making the approximation that all of the cyclist’s energy wyg/3sfm 1:. zkbtad5rl t60 ogoes 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 a79.r ky j1wcqpt 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 ofh*:rplqml4 dv 3 jnov37e9s i1 mercury 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 atml) ybr23dkc 5((+.xvlj:gs99en azcf umaz9 $250\,m/s$ 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 movingu6m/x9heacb z5d8u .i 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 the 8.2-g lead buu) ssv*9y:2nk (pw ((bkzkskx llet that was stopped in a doo(xzn2s:(svy* kk)(ukb9 s pwkrframe apparently melted completely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod withzd0dm k.cmo(-l p w(j+ 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 injak -c0vj)eyx 9p+ r8l Example 14–10, assuming that there are strong gusty winds and the0- 8cy v+jp) rxeajl9k external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tufj7zs(o v09 xamuf klo 4f5s;5ngsten 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 20 2d2nm/kqp w8tnq(syv 3 mx9)r0 W of heat flows by conduction from the blood capillaries beneath the skin to the body’23qt q()ynrv k2 xsmm8 n/w9pds 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-thick brick wall. Becaus tym /;e tzerf75j/io,e of a number of 100-W lightbulbs in one room, the air is /tt;7eoe5 rf,i j/mzyat 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 a02yqw4xn2 k+r heg 9u+dcn9sb 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- ;+of8tiu+8mrt k sxz-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperm8;t+uifzx-+or tk s8 ature 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 comih u,vd ucm y;s9l.u:) sk0v:nstant, estimate the rate at which the whole Earth receives energy from the Sun.u dv: 0vklmh)cu;,:s.m9yiu s    $ \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, yx94bxsmoj)1s1a1 vepfw4 c0 which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is x1xojcpw)41fm1vbsa s 0ye94 the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a 1 ablubaz)m7q*2 n0czhouse come mainly from a 4.0-in. layer of brick and an Rc)bm2al*ba zqn u7 1z0-19 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 two panes of glass separated by an gma41b4u,o vn r)c j/dair space, Fig. 14–20. (augcna jd/ 1b4vr,4m o)) Show 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 long should it tq5tv j9;u8vl hj5t2mdake 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.,.gwk1a j .ftuz.dj z.20 kg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much thermal energy is lo;hedg yc8l- *tb m;,contained in the world’s oceans, estimate the heat liberat,o; hymc-l d8e*lb;tged 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 i4pt4o; v tsxi.lr4ct(t into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. Afte;4r tl.p4sit c(vt x4or 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 spal- nm, d.6pdspce by the Sun, assuming it to be a perfect emitter plms -pdn,6.d 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( )qw ewep29ao-kg person may generate $200kcal/h$ Assuming that 20% of this goes into useful work and the other 80% is converted to heat, calculate the temperature rise of the body after 1.00 h if none of this heat were transferred to the environment.    $C^{\circ} $

  A 340-kg marble boulder rolls off the top of a cliff and fa ea n5d,wmau10dgcatlo /a g1g 0a+0s)lls a vertical height of 140 m before striking thu,11/w ag0 cg s5gle+om aa0ddna)at0e 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 inlvw1yg/ * v+g.otodd +mg4qh+eb9 .3z poslp,to a 2.5-L insulated pail of water initially at 20.0gqp gzoe +twh31,lb4doodmpl g+ vs/9.* y.+v$^{\circ} C$. 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 mavaqi3o/ u, kcyjts 5:1y xwy)p4.-c3.5 cm thick with total surface areaj :xct.3y-5mu/k, y1)y4pcov qa wais $1.2\,m^2$ 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 avkfpwu+ /wg/q(erage 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 interior of the bodyrf6xp ta7l9a8 lr .g(y to the surfacpyflta r.a9xrl(6 g78e. 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 c+:hvc ce r xo-cg)k8.hm thick (assume conductivity of air) and arhh8eo)vgk+ c : .rc-cxea $410\,m^2$ 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 he48:f fyr1ogqfg ,/d e+hn3dat $220\,m/s$ 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 y *kh/sx(myk k.z+j3v(n mao2part (a) in Problem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a tempevk+(h3(y/m *m2sk .xyznoaj k rature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If itql2z lr; i4vn2s initial temperature was q;l inv2r4zl2-125$^{\circ} C$ 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 c9qml m*s-kt+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 hitksx;4m8;)ufz ;vc qmzuwel z 7zf9. s8 a soft rubber ball at a wall until they are about to drop due to dehysk;9 e vmzw;m87q. x uz4fsz8z)luf;cdration 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 equal masses of ice at o*1jt a0 mfn-tunq*7y 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a personzj5 m4d*l9 /43jb+mm(q9wc9a x jaujyyj nry1 can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperaturj/a 1j 9(dawy xmym jjqlz*4mr j94n+35bu9y ce 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-gal tu4hw1 ua7)cs(185-L) water heaucst1 7au)hw4 ter. This suggests that the tank has emptied and refilled with water at roughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a 60-Wt 9zf4azj2f6ce+wsfy gg7; p, 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.    $^{\circ} C$