What happens to the wo6 yrnaozsl (/6rk done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does lo/a *a bvjca:v/c/u;0abxv8 temperature flow between them? Are the temperature 8*lc0aob:avbv v j a/;cu//xa changes of the two objects equal?

(a) If two objects of different tempqm9 nl h;-v.u yn9jpp8-rwyq 6eratures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Isnw8 v9jypu; -pq-l9h rmn6yq. 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 mals46 1o8xzt gty drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the even tt4s og6xz8l1ing. Explain.

The specific heat of walbn od4ph52qryxwq*7. 2 vq) bter is quite large. Explain why this fact makes water particularly good for heating systems (that is, hot-wat)n l2ovbw q5br7qx2 p.qh* 4yder radiators).

Why does water in a metal canteen stay cooler if the cloth f bh43 kvqs0azv n:h.ng13o j7jacket surrounding the cj0an o4h1 7bgk sqhn 33:.vfvzanteen is kept moist?

Explain why burns caused by steam on:.g8: phzv uqv,n lg9noagzyr76+9x d0t 6swy the skin are often more severe than burns caused by water at 100 h+p7 0v,8ztd. ygz:s6xuo a6gn 9r:y lngq9wv$^{\circ} C$ .

Explain why water cools (its tempera 2gc2gc )0v mvj)ek5qvture drops) when it evaporates, using the concepts of latent heat and internal e0 g )2ccemv2vg j5)kvqnergy.

Will potatoes cook faster if the water .nvt0 p1yct *r cm23ema pzsf,5in26 mis boiling faster?

Does an ordinary electric fan cool the airu y 4y8-*miztqt zq z7r6jew4(? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the t5mqgyd1xt+ vv 4u qa4x(ol x2:emperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have7lbm 6z8ux6jxx lke/7 survived by covering themselves with snow. Why would they do that?6zem7xx lxul6k7 8b/j

Why is wet sand at the beaj*ny s) 8uy;kwiwse1+ch cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that *jwq8j )m tl(w wlqu f6y)r6 rw186jpsmean that its temperature isf686tlrj(w))qsl j yq 1 muw*wjwr68p high? Explain.

When hot-air furnaces are used to heat a house, why is it important that tsv/j)m +n ,iv 1btgr-rhere be a vent for air to return to th /+r nmg v1jtvbi-sr,)e furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes r1 5*qbk kfcfg,eversible, so that they drive the air down in one season and pull it up in another season. Which way sfk1k,5 *fg qcbhould you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inchejv,kura8:-hm (a 5 2.morkvmds or centimeters of loft, the actual thicknr,h5djomrv8 (va .k:-2 ukammess of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sin cal r-lh1z0k) dmvc0k: pe,y.k” glued on top that looks like a series of fins. Why is it shaped like lldm.za,eckpv 0 0-1k: rcy )hthat?

Sea breezes are often encountered on sunny days at the sho-ek2jw0d . 8dropm m/zre of a large body of water. Explain in light of the fact that the tempodm-/rjzd82 wk .mep0 erature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the;,py3 ckg o8x.jr7xua air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Expl.o8x r,g u3c a;7kxypjain.

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

Explain why air temperature readings are always taken with the theijrwi,o/* trd4 lq5 y;rmometer in the *y i,l5ji4t;qwo/rr d shade.

A premature baby in an incubator can be dangerously cooled even when the airvcd+xi1u0/yoil,;n v temp n +odl1,ixvyv/ic0u;erature in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it bv v bk mf24.j)unt 8k1) e.ymd*t:veihave a vacuum between its tv : fb)nj yv*v.kk em.imudb81 )t42etwo walls?

Imagine you have a wall tha s(yrw15 hy7px :mvyy/t is very well insulated — it has a very high thermal resi7 (hy:syp1/ vyrymwx 5stance, $R_1$ 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) venti*y:lu (nrfgsc*lty( j6m ,ve 6lation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explalcyu mjrtly(6g *(fn,ves*: 6 in in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny med op2s,8)s .xlsackw 2tal. Yet the wood feelws p2c s.l,ka 2xod8s)s less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly whe- bs/n1nn/fqf n the weather is clear than when cloudy. W/n/qff snb1n -hy?

An “emergency blanket” inq7 h hn r/r5vk19ymp;s a thin shiny (metal coated) plastic foil. Explain how it can help to keep an 7rnm /5pnhhq k9vr;1y immobile person warm.

Explain why cities situat+wbuu5m*g9nw,yd 2. hewc3b ped by the ocean tend to have less extreme temperatures than inland cub25 +wg3b w*,dnh9cyep um .wities at the same latitude.

  How much heat (in joules) is required to raise 8n3gy4,e5u*y c) : efxs6adisw4ql bgthe temperature of 30.0 kg of water from,scdy e84b*:sal3 6qx)y5gfeug n i4w 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is init spacf1ky0n us)/8fx 5ially a 5x1)k8 nufpsfy /cs0at 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cafi bsbi:0epub w*8;-r 3e,qv wl 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 :3spivm *47vbbz x o)bin the British system of units. One Btu is defined as the heatbzo: b73ix) vvp*m4bs needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genegqf78bz nir 5 1b3a/as0xpj9x 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. Estimate how l9iflxg )k0wr8ong it will take to heat a cup of soup (assume this is 250 mL of water) r8f9wgx0) ikl from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes zoywyq- 2f6l 5are used to bring a 1200-kg car to rest from a speed o y6-y2o f5wqlzf $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How rtz /c4b.yi9ahgnq *g,w-z 0 fmuch heat does it absorb if iti4 a,t9fq 0.rhwygb n/gc zz-*s temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of ac6wortj sidc/q )z)w3/9;2xmguj lr - metal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 18 icrwsml9-u/z6/; g2jorc) wx)qd jt3.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and wxt rk/ba ybr+g3a2z6*g *fp+l ater experience the same temperature rise when they absorbb*3 a+zfx 2by g6+agtklr*/r p the same amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21.vko1d 9mub l*j964bdm fmj9u1 6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibrium temperature when a 245-g blozq-kir n3jq87ck 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 =-no4nc3 o, (uga2fwu y $0.4\,kg$) 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-q(kvi7-hm hmd 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 19:dawyyq, haqe m-9m bring to a boil 0.75 L of water initially atymqm w,:9-9yqdaah1 e 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 s-nif /zp12qameasurements. 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.fqs/nap1iz -2624 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 ironi m7;ns,0:wuawr7 m lb 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 3cbeoyk;j+zx /h4or+ a hammer 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 amoxjl* io:3l 2jxunt of heat needed to raise its temperature bli* jxxlj 23:oy 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 1r-n:w( o3ozk-ir u+ qrbn,z;f 6.50 kg 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-hi;hehzc s-z,l9tfxa* n )3s+dpgh building. If 65% of the thermal energy prodz;l ax,spd3hntz9e )-c+* hsfuced 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 evaporat)z0pb on;t+qy ion of water from the skin. How much w+tz 0b ;)qnoypater 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 inw0n,kf34q6 igb r8hxk d o-zd.to an insulated container of liquid nitrogen. How much nitrogen evaporatkdoz4r6 3.hbgnw ,fq-kixd80es 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+r)vc8m y9s )9oz2bahnqpx( g from the 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 230 kg msh w4qmp6)) /pqyha6 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,.hd+f5+m1b-kq dm0bi c vs fu0 a bicyclist consumes 8.0 L of water over the span of four hours. Making the approximacdmkm+.fb00 u h+iq vb1d-f s5tion 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 at 1l*.ppb/l1 :urbtotc 9 00$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of mercury i0 /av-a tq qa (f((ejoxb02wexs $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 .vvt;13vvp2mis ukiw -nz3r, $250\,m/s$ 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 movi30hh f4v,olw snvy(/nng 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 b;roomaxltn;2oag40 ;c .2k i hullet that was stopped in a doorframe apparently melted coml 04ciogtom naarko2.2; ;xh;pletely on impact. Assuming the bullet was fired at room temperature (20$^{\circ} C$ ), what does the investigator calculate as the minimum muzzle velocity of the gun?    m/s

  One end of a 33-cm-long aluminum rod with a diameter of 2we;5w 0v ujivszy05 .v.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 conqno cl1m5 a8)q5bxc2em803 ycqyznl4 duction in Example 14–10, assuming that there are strong gusty winds and the external temperatu 85col103)m ybc cq852an4 x ynqqlezmre is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by sy as/ vfg*x6wr 7o2tv:+wsi 8y p3kd3a tungsten 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 heat flows by conduction from the bl.0tb , nr0mlhvood capillaries beneath the skin to the body’s shmbv rt00l,. nurface 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)n l(y4wreq z82*dwtr per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air(tn82)rqdy*lre z4 ww 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 t 4rzt5spy 45y6wryii0qr,dt )o 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 aret v 71: wfeoc(vlrhatx 9 ).nuxqn-8kr/- baa5 attac(9lxratxtfvnb a1.n qw ca8r-) eo/vu:k 7h5 -hed 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, estimate the rate at which the whole Earsm 65ex;dyp)f th receives epe 5 6d;xyf)smnergy 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 heat, which is dissipjz;:z.wzd w k olb2e9xo*/vm* bpp,ic ta (2;bated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the different :2(z. *;x/*vb9az jzcb,owkpeom d ip;wb2lce in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a hzu* uo-dfix: 7ouse 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 loss through sfo:iux d*z -u7uch 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 pnjbu dd)9n 5/k, f)qlair space, Fig. 14–20. (a) Show that the rate of heat flow throuk)n/9 5dfu)dp,jlbn q gh 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 a5 0ew2 sdv- kb)et:ffshould 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 mlh i:m:6+kils(gj:bkg 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 isvvm+hl 1,tk;g contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, g 1 tkvl;,mv+his cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is te dan*d.mh9 o,wsted by firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb al.*a n9d,hw doml the 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 radfyt9 0/ethcg*iated into space by the Sun, assuming it to be a per0/gc* heyttf9 fect 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 activityk* cusr,cg.x* qw 8ic-, 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 rocn(8wvim e+; hlls off the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature r 8iw+;hmcve( nise 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 initiatu (u :37kuibx8yd+,t t/bsls lly at 20.0st iy+x:7udl/8t t ub,ks( u3b$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick with total sur/60qvan0 n,prcf :hjuh 5r;x kface arekuxp,nq05h6a f;hvn :r0cj r/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 averzt.h v wcxw:y1 s3ecb9eq zx: qm9(k(*age 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 e4ow:j-ua9*h5byv oo conducted from the interior of the body t4o-v: o e*aj95wuho ybo 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 wallsvu z u0c,8ys1esnk+,g 17.5 cm thick (assume conductivity of air) and au0+, szecn1k,us8 vygrea $410\,m^2$ 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 traveliopa g-31 6/i1wtscy1,bmfqv vng 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 accou9,okp gmumq k7+.as5r nt radiation from the leaf to calculate how much water must be transpired (evaporated) by thrau sm, p9km7g+kq.o5 e leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s gng1 rl 6asx18atmosphere. If its initial temperature was -1s18 6lxgn1gar25$^{\circ} C$ 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 r 2 do+zesi.z*crust increases about 1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit a softny7u8hp2) b 0 rs*0vcytanwq8w91t dx rubber ball at a wall until they are about to drop due to dehydration and exhaustion. w * vacpy908d7yrsqn0t8b1wnu2 x)t hAssume 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 resur:2jo*p m k* ixx-.hvf ac9jbej+ -gtcri3.. flt when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conductb k4/e *uj1)-yeb*)fhs tyou nion and radiation at a rate of about 200 W. Estimate how long it would take for the body tem *u nbkt )ye/y* u-s)h1bof4ejperature 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 b9n.lkpgvgx3jr 9w8( cu 7d5 hwater” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at roug. 5gn (dkgrl puv97jb9w ch83xhly 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 i7sh yttq.g*x) s 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.    $^{\circ} C$