What happens to the work done when a jar of orange wi b9;vyd cp36juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow b v(shak.m8wp ,6k37hps4nfd(magm ; 12ou kcyetween them? Are the temperature changes of the two 1p2skky 8nmp;wvam,fmh76k.u(sago ch 4(d 3 objects equal?

(a) If two objects of different temperatures are placed in contacdn+0p2fhrz90 da 8csjlzm +m*t, 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 e20p rfs m jdh+zznlc09mad+*8nergies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the tempd cbg;hc+ m*) :up8utwerature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering thc*u :8g+ tb;p)cmud hwem in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water pa57 cre+c3egb d,2gvfny*wz w. rticularly good for heating systems (that is, hot-water r+ v g*y5fc32zne.g7dwrc,we badiators).

Why does water in a metal can9:2.6m)gop59 izusexbb j)huknr+ti teen stay cooler if the cloth jacket surrounding the canteenhi b95n ug )kre6mb)pz.tj 2oxi9u+:s is kept moist?

Explain why burns caused bfvj u 15;vecs)y steam on the skin are often more severe than burns caused by water at;fve51s c) uvj 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, iw/k88qbrccp4w u( u+0so*x+enn2 rmusing the concepts of latent heat o8 kn0w 2xmq4/s w8bu+ irncr(*c+pueand internal energy.

Will potatoes cook faster if the waterw/dl b d+s1y/g is boiling faster?

Does an ordinary electric fan cool the air?vfd-z (x- 4ci(yx7fkv Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the tdc+m7 tz- jz/qemperature 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 them1mwoq 8zx vr73selves with snow. Why would they do that?wo8x7z3qmrv 1

Why is wet sand at the bem2ll,gfco4 .1.ky 1gdo+wys each cooler to walk on than dry sand?

If you hear that an object has “high he lxzhn)c,n55v at content,” does that mean that its temperature is high? E5znv, x)hc n5lxplain.

When hot-air furnaces are used to heat a house,:m1d xfj/ rt9t why is it important that there be a vent for air to return to the furnace? What happens if this m:rjtd f/t x91vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in 2 jk,5/+;rzuyd zlai hg3dy t.one season and pull it up in another season. Which way shouz .rdz/y+kd5 a2, iu3jy ;ltghld you set the fan for summer? For winter?

Down sleeping bags and parkas are often spa p4srac p+bqajx3 7dm:5(2m pecified as so many inches or centimeters of loft, the actual thickness of p4c+ a( rm53xap s2b7jqpadm:the garment when it is fluffed up. Explain.

Microprocessor chips rawy-,gxs6ao llz) : v1p42vgclma83have a “heat sink” glued on top that looks like a series of fivl)yas6wg 243 gmxp8,1 :cal z vrlo-ans. Why is it shaped like that?

Sea breezes are often encountered on sunny days at the sm1;. qkdmf+sghore of a large body of water. Explain in light of the fact that the temperature of thg 1+skmm.; dfqe land rises more rapidly than that of the nearby water.

The floor of a house on a foundaiy;v :egon2- btion under which the air can flow is often cooler than a floor that rests directly on the ground (such ov;e2 gny b:i-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 rea/ohq):f ub0 2*:kpmx4hj7t dd: yfekadings are always taken with the thermometer in the shade.y:4 h 2:70ajx:t/e)dk d* qfu ohbkfmp

A premature baby in an incubdsynd1t ,aw** ator can be dangerously cooled even when the air temperature in the incubator is w 1 a,ndyswd*t*arm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it j2r(o j(snm) lhave a vacuum between ilo n(mj)2( srjts two walls?

Imagine you have a wall that is very well insulated — it has a vhq*- ybg-zh*zery high thermal resistance, hqz - gz*hy-b*$R_1$ 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 prol(uc,madku21 cq,y8 vcesses: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first t ,8(q dukmuc1vac,2lyhree, 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 lyingo n*yp3j8uhx 2 in the Sun absorbs more heat than a piece of shiny metal. Yet the wh2yp njx o*u38ood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at nev-y3 r6:fusdk(s2dwight much more quickly when the weather is clear than when cloudy. Why?62 -sd3fu krywsde:v(

An “emergency blanket” is a thin x1crxwtd wu.22x,4k( y2wc ppshiny (metal coated) plastic foil. Explain how it can help to keep an immobile person warmw d. k2wt4, rx2cpc(xxwp1yu2.

Explain why cities situatedib migco+ wm;5h+i+n0 by the ocean tend to have less extreme temperatures than inland cities ati0c 5o+mbigw+n ; him+ the same latitude.

  How much heat (in joykdl0of f y8.5ules) is required to raise the temperature of 30.0 kg of waterd.lofyy k50f8 from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kgy-/ pd9l 0qsqde9;ql y.gp/hr of water that is initially at 10pd/ shy.e9q/g9rl qd plyq-0 ;.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a day.v3th;-jvy t u),, qmhm
(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 the British system of units. Oygx6 :9h6jk6a/ cungkwb(h3 vne Bt a3juvhkk6x(9ngw :/yh g6 6bcu is defined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gener/+ av: wt0-elh i9hx wol.-nnoate $32,000\,kJ/h$ 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 35 fwi ie.0q3y1f2 7h b ,94gxkyvoh-tbh0 W. Estimate how long it will take to heat a cup of soup (assume this y32fk7bbi iw4 fg eh,thy- oh.9x0v1qis 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories*7:*racvj v4v7mr bjs are generated when the brakes are used to bring a 1200-kg carc4rj77*m sj:a rvb* vv to rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of w q(ar/av1le6 5(wheowater. How much heat does it absorb if its temperature rises from 2 5o q/ler6vwaw(h(a1 e0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is needed tk 6vp-td;. ppho raise 5.1 kg o.pd6v k- ht;ppf the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experin,-ami+ ydoow*mxwx+v6 29w d ence the same temperature rise when they absorb the same a2,o dvw +dwxy-in9x+m 6m *awomount 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 thermomfn)8f. c5 wmh,tlxv:eeter reads 21.6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibwc;h5qvmruv(7u vr;8 rium temperature when a 245-g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe 4vh3 m xnv)dn7(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 substanc kzk za99mk1ahbhmx1 ql *mzzy/n: +)7e is heated 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 of water ini ev)fwz; ps*lb,g( :rctiall, pc:bl) fv(swgzer*;y 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 gw ju 3+2trj c3lbcj,/r of candy from 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 /3+jj2,t j rlwbccr3ucup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron *r(;ssd2 60rw ppdu5 cd5opida qu9q3at 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has)iy4m95 msy sp 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 dob+dza: r0:p vefined as the amount of heat needed to raise its :boprza:+v 0d 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 .b0g)a7 jmkzyq. hg:o:yc bw*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 buia2t)/ i3wua eflding. If 65% of tia) ut/ wa32efhe thermal energy 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 evaporatix/1+p b0q(bh*jbkm pson of water from the skinsp0m1bjpq(/xbk+b h*. 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 px;18 kfz v zz:cb*dso-a crj gz*8b/b5oint 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 v8rf* o 5czzvbb:jz 8c;as* /dzg-1 bxkaporization 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 at9u.jk0ty) e pj3(.5yidy sm qu -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 c wps;q;zw 6o,bontains 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 bicy; z* h 6jmfjf,tx,jw:wclist consumes 8.0 L of water over the span of four hours. Making the approximation 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%,,:w 6z;jfmwx* h,t jjf most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 100l+x,y vvju 71q5cic9 )i3jy om$^{\circ} C$ 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 ,bmn3o5 yuog1fg*3h his $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 travelin a -p4per6afji )1nuez/l /(org at $250\,m/s$ penetrates a block of ice at 0$^{\circ} C$ and comes to rest within the ice. Assuming that the temperature of the bullet doesn’t change appreciably, how much ice is melted as a result of the collision?   g

  A 54.0-kg ice-skater mo-.wqr y i.h*pfving 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 noty rqwp3q; 2(t7atqyc7 ho t7t7es that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming rwa27; ytct3tq7 tyq(pqoh77 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 2.0 cg sar/ jmawi3y9io -k tob)(;0m 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–wwxt5mpep14g 82huh3 10, assuming that there are strong gusty winds and 8w5g2hp mpu1w3ehxt 4 the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten 7dzz16 tjky l+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 tpo0nrjw 11:hthe blood capillarie:on1r t1h0pjw s beneath the skin to the body’s 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 p*s( rlqeoj4q8er side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one roomq l*(es48jqor , 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 ic*b1- hfjkvb )y.lbafe9jqy z t::n4k+e 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 leweiztgfo (g+9q-./ y ingth and cross-sectional area are attached end to end ((gi 9f qotzwy.g-ei/+ 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 to 6vi7n6o hod;he rate at which the whole Earth receive do 7h6n6oo;ivs 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 5nn u/d.u.tb vof heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the differennu t.5bvnu.d/ ce in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly qrz3 ro6 r4j 2 ab4wp5o8pzv6lfrom 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 pr46 rb348ovjop5 2aq wrl6z zof 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 separatepw 7c8d,fbtc-3o* adz 7q;b f1+teocad by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by con dfcbp,+c w;f8 *3baecq7oot-td71z aduction 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 qmejrue.vi +* qfcm/0d7g2uhg/wdw/d . :r- l11.0 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 abou-no(g, wugfc)t 0.20 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 contained in the world’s vtv bp; l- sok )zawhd6nwkq.;m+:8a-oceans, estimate the heat liberat8ta avwdzp6n-k hvw sm-k.):+;bq ;loed 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 s 5:g( dhbqvp*by 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 been reached, the system hasg5q: v *bh(dps a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated intqs-z2j+9bq vgo space by the Sun, assuming it to be a perf 9 jz2g+vqsb-qect 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 activityo xpf2qpg+:h5lu 0t: n, 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 boulde5zf- toukm4 3feddga-te3c;, r rolls off the top of a cliff and falls a vertical height of 140 m before striking the gro-4tz ;k-dtecaf ge35muf3d o,und. 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 5q gm (ir/i+hypail of water initially at 20.05g( + rhmyiiq/$^{\circ} C$. 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 dw,b pl5 gu+1vthick with total surface are,gv5u+ 1wlb pda $1.2\,m^2$ 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 metabolism rate of aq51jd6kopf3 dw p+d z*bout $950\,kcal/h$ 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 whmjm.9gvz1 *:xixey s;ich heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 19x:*yv ;jz msx .gmie4.0 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 17.5ki :o)(s9bx r,kj2og i cm thick (assume conductivity of air) and area (bjk9)gsr ii,2 :xook$410\,m^2$ 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 att /z.e:m8fg ny9inb5i $220\,m/s$ 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 part2zwq wdjwu5e0)s v .q2 (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 temv5wsq2ww0dzue j2q ).perature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphernber/5:hu i-j e. If its initial temperature was -1 / r-niujeh:5b25$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s crust increases my wgpd+fmsk:j .0. w9about 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 ball at h,gxbpg6 a-c *a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity o*6x,pa g-bgchf $22\,m/s$ 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 equa0,on1ppt1f ip0r*z n.6s yj7uc*mx i zl 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 at (nx 9-3rd* hrwdqig.gy(jfax h78r; q a rate of about 200 W. Estimate how long it would take for the body teqd h.wxgrfrhd*(qr3y8 a79-;i gx(n jmperature 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 ae:/pi)q ,kz+ll uhsr:7g k3kh-j i6oind dishwashing, there is “no hot water” left in the 50-gal (3 s:/zie: p- i+jkk klhg,r6 i7)hquol185-L) water heater. 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 a3d xnuc fay,23 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.    $^{\circ} C$