What happens to the work(t8v 4s5gu hz9c1vegdb ou.8 y done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperatqrs:rwkgrh 9m -a/ya86u:x2c ure flow between them? Are the temperature changes of the two objects ec: x:2sm qka8w96ryr-aur/ gh qual?

(a) If two objects of08h zpcupw f6vsmv 0y :d:e0,k different temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the pmw8 0sefu0dv y,:kh:cv6z0 psame? Explain.

In warm regions where tropical plants gzf , bj *v)sma*j-/4zaq,uia frow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can bajb/im -*as4ja fzu ),f ,zqv*e reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes wate(a4,w avjrii1;sf gw9 r particularly good,4 agrf;v1 i( ww9isja for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroundfpno+)v c-e8 f;o 94t vvm3vwjing the cvjv f8v-t f3e4 wm9;o )+nvpocanteen is kept moist?

Explain why burns caused by steam on the skx) 0s(lw5dab rin are often more severe than burns caused by water as) rd0b(5wx lat 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporate5j *f1eq-cj,cxy)r fss, using the concs jcq-efy* 51,r xfcj)epts of latent heat and internal energy.

Will potatoes cook fakb0bqpkzsp-bvo18u ;9w* ma - vd8jt-ster if the water is boiling faster?

Does an ordinary electric fan cool the air? Why 9 l(tle46( wjom bovn:or why not? If not, why use it?

Very high in the Earth’s atmosphere,a 6acby6pex1 pr4v 9(cvgo 9h+ 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 survive;,ngf6 h b8 fz.4u zbzen7;alhkc3wj4d by covering themselves with snow. Why would they c4 u6kzb 7zb;nha.4fgh3 j,z ef;8lnwdo that?

Why is wet sand at the beazjrrx 6om1b 3s)do:4qg+j,1 rb2phnt ch cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does thatmrb -8/gaw 0yh mean that its temperature is high?ay/8 grbhm-w 0 Explain.

When hot-air furnaces are used tkhh e86kz:jq (ur*j8 po heat a house, why is it important that there be a ven*ej6k hk(u :pzrj8h8q t 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 air down in one se cd+ zyymtd /;i1i4gj/0io sx8ason and pull i/i 8i+d1;gjc4 imzs/yyx o0tdt up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inchesb5z 1f 24qe ku;9ojp*f40n0ww ocpmgu or centimeters of loft, the actual thickness of the garmeoz1kuj;*0uq4 epn o 5w9wpf0 mc 4bg2fnt when it is fluffed up. Explain.

Microprocessor chips have a “hedogwgv1orlf me *fl , x3/57e+at sink” glued on top that looks like a series of fins. Why is it sha,* o+de3xlv g7oe1g5wflfmr/ ped like that?

Sea breezes are often encountered lp*e 5cslnd: 2on sunny 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 np*ldc: s2le5nearby water.

The floor of a house on a foundation under which the air c1 ,6z16cnun dtmqm *gwan flow is often cooler than a ,qm6nt* 1cdz nmg16uw floor that rests directly on the ground (such as a concrete slab foundation). Explain.

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

Explain why air temperature gf3 bl usa-go o3py;64readings are always taken with the thermometer in the u3o 43g6 yoafsg;blp-shade.

A premature baby in an incubator can be dangerously cooled even when the aq wd 4sq6in vmqn);8gm15 :gklir temperature in the incuqk)1l g;4nv5mm8w q 6:gqsidnbator is warm. Explain.

Why is the liner of a thermos bo3mwga;dv) r1i9 uv czauqu3 x9 ea/u87ttle silvered (Fig. 14–15), and why does it have a vacuum between its two wa9azeiuxuvr ucm1vu3) w9dag;3 q 8/7alls?

Imagine you have a wall that is very well insulated — it has a ;b /uwa0oxvc)21g3 1iar ::vlzx ulmnvery high thermal resistanbv13a an0rclov 2:):xg wx luzium1 /;ce, $R_1$ 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:m rhb4 o27oynx zgn;4) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass pan 4:orzobn;7hgy 4m2xn es; 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 than a piece of shintb :fo njr1m4 3-8afpzy metal. Yet the wood feels less hot than the metal when you pick it up. Exfapz :r-o m43f18t nbjplain.

The Earth cools off at nipdae lm yy/ 4(k8.0nauq+aq :wght much more quickly when the weather is clear than when c/0a+e.p(:lq 4qw auky mayn d8loudy. Why?

An “emergency blanket” is a thvtso.a/ 2iy0;z6 qb1y7 wd suhin shiny (metal coated) plastic foil. Explain how isi1.atq0/y6bwuhsv d y; 7z2ot can help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme tempu;xmm*v)aiq3 j q-6uk eratures than inland cities at the same latitude.vq m u)qm a;*x6ij-u3k

  How much heat (in joules) is required to raise the temperature of 30.0 kg of wy)/ bido +0unhater f/bd)o h uy+i0nrom 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 nlgcf:t 7xe .o:)wo*iinitially if ):wegx7t.oocnl *:at 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person 9r jflpvhmapozv3)8/ 9z xa +7consumes about 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 unit (Btu) is a uniqc y2y,.qsy.1)b uux ft of heat in the British system of units. One Btu is defined as the f.y us,qcu1 b.2qyx)y heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate -m mc-o/- /wjzd kizw+$32,000\,kJ/h$ 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. E 4(w913z;y erae fq6h9rjfs 30twderpstimate how long it will take to heat a ce;a4hf wf09eep (j39 163qstrrdwy zrup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when 4dx7 j8grc)5,5 dfbjjxzcf:f s7z c3wthe brakes are used to bring a 1200-kg car to fj:8cz4 sjzxbwjd cf)7 cd5fx7g, r5 3rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling syste.j )n35do :zqegz) qcx5u(uz bm holds 16 L of water. How much heat does it absorb if its3xqzd)og:z)5qu u5( b jnc ze. temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ9uzg ss bkl6c:h26i -y of heat is needed to raise 5.1 kg of the metal f6hsg2 ylczbs9- u:ki6rom 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same l5g- yv3 4.mtp-mfx/bi1 z n9 dt;i mximhy*o7temperature rise when th* xpb7mlmnmof.m ;/3gi5vi - 4t9t-hxdz 1iyyey absorb 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 readz5 6;uggk 6l )fp exj( (cd,jo4uf/jlss 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 equilibrium temperature 8trn sw bjuge6+ 3blj((2;upu 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 oa-1wmnvw kuusw+g*d;9*be1 (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 st xbv)ck :1r y-/fgefxe.d1d/ubstance 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 bon x:yy3 t0q;z8ujg o9dil 0.75 L of water initiallydujnztg0q839; x : yoy 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 measurements.7*udwp( 7pf zt 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 temperatu(pfz d7*u7wt pre 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 m 7:d0+vk( gifrom -srdsc5aixx.84airon 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 hamme5fkgt )+vfc2owt 7/srr 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 defbb:l/4(5zqe: vdwf *ak zw z4dined as the amount of heat needed to raise its tempwdlz: kvb/(:wq 4*4ze 5z adbferature 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 m8xel u 3n5:hddelt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the -d.4uqf mfw8 3 y4tceu4: xiv1o7e xbzroof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorb 3zd4f u.uxb1emy4fco wxi qevt84:- 7ed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give offqzqea4+; cs(g 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has beeqq(4z;a +c sgen 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 d-s oop7d;hsmi+f2z 8mropped 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 vaporization do;oi8+hm7zs2fps-m 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 fo85lb yg,n jsghy.(-fqt(:y xrom 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 cj3q 2qljp ;*zpontains 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 cm8*d 7n-e4 br wamy 7hsx6yef.oc( /hvonsumes 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 ridecse7av4mro e-d*( mhfhx .yw/bny67 8r 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)m oca.; nhn*x 100$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of mercursl+2zn*47htn:*mo r 5p nykd my 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 g6u4 cnr(d/wg 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 movinhs9; 6yxc1s+eavumz 3cu0+g kg 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 forensi 6xagb 1g3yg:gs +w6kbc investigator notes that the 8.2-g lead bullet that was stopped in : g6g63xygsa 1w+bgkba doorframe 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 with a diameter of 2.0 cm is kept at 46iu 7g1gk0f p:u0$^{\circ} C$ , 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 Ev)jsz-u: o;vsn(m vb:xample 14–10, assuming that there are strong gusty winds amsj z(vv-no;s v:)b: und the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiat6 2 er6tbohx6tq b:2vped by a 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 bo6.hq0k apbl 1c,hx 4,j lxbv5lood capillaries beneath the skin cljh5x. axh ,v41p6q,lbb0ok 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 per side, share a 12-cm-thick brick wall. Becaugn/hjik; 32)p9 axv y1(dzi iese of a number of 100-W lightbulbs in one room, thephjixvy e3;i2zi na9dk(g 1 /) air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a block of ice 7gb aok4lo2 d;g uay5by3n+ h/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 an/l/gx;+ejvfav0am1m l0zmlx3 .lo a 5d cross-sectional area are attached end to end (Fig. 14–18).0/mo gmlae0a l./l;mva 1z35j+v xxlf 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 whicha, oj u,qi*z(b the whole Earth receives energy fro,b*iz, aq( ojum 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 dissipatov. *( fd)+ rsl aqqv5rapa7:bed through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is thef 57 .a:bavldvqo) saq+(rp*r difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the +pc yp6d*b e:f :k/avgwall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown yp k:v ecfb+d:6g*p/ain 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 s oye/e)pb*m7jo+2x 0l9e , v.f tvokvdpace, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conductione.9,v/+em0x ojp d kevt) f7 2byov*ol 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 .lj1 6l4p bkr/ likp ne81pe)5iob-s j0$^{\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 ab/gts25n*gru4yx3j wzout 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 oceand2m- r:k7hu55eh gfz js, estimate the heat liberated when a cube of ocean water, 1 km o je 5mu r:h27-z5hgdfkn 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 it into a fixed block of wood with.uoyan;v o+ 8pwxy: q/;zrsi 5 a mass of 1.05 kg. The block and imbedded bullet together absorb all owz/.r ;ay+v:q5p 8uyni;oxsthe 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 b6sgsewtzsrjg ypkxu:7(/ *7 1y the Sun, assuming it to be a perfect emitte tu:s7zg /s7k1erp*gjsyx( 6wr 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-kgjj36y) pq g2zh 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 falls a vertical heigh/iuopw *2ynz 2t of 140 m before striking the grzno/wi22p uy*ound. 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-Lw-1;hz( sbulb e3ri au881cmkczr4dxot61u . insulated pail of water initially at 20d1b1iaxt34cu o lr6w- sh.kc m (r8b;eu8z1 zu.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 3.5 cm thick wi jog/z/ a:gx fw.2p(dith total surface arexp:( oj/w .g2/zgadfi a $1.2\,m^2$ The temperature at the surface of the clothing is -20$^{\circ}C $ and at the skin is 34$^{\circ} C$. Determine the rate of heat flow by conduction through the jacket
(a) assuming it is dry and the thermal conductivity k is that of down,    W
(b) assuming the jacket is wet, so k is that of water and the jacket has matted to 0.50 cm thickness.    W

  A marathon runner has an average metabolism r q,d3-1 wevqn.m3vtsod )sg y(yb y98sate 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 ovv3.no3k5eh s n 9z/ cmq0op+lf the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is at 3 .pz nemo39lckv3vn0+o5 q/hs 4$^{\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 (assume conductivity o5;cdtlu+f -zi-3qy0 puu 6k pu. s-sckf air) and a.c; d 5pctuklpq-uu 6i-zsk03 s-y +ufrea $410\,m^2$ 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 traveling2 ud p9y;c8rafyypq vb,t(*a) 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 account radrg+v 6rmvk fnh,v,1 p(iation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature h (mp1r6fg+vv knvr,, of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’sk k+9(a7 w1sb0sfppq*e-wh gy atmosphere. If its initial temperah*+ass9p-f17pywe kkbw(0g q ture was -125$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s8h++gg1a7qvu(fc 3i i:xt2ks alqvp 0 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), ts ) blcp;(vl+pwo people hit a soft rubber ball at a wall until they are about to drop due to dehy)sbl;cp (v+pl dration 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 massese-n7wx35 z i)kp-izt e of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can l0czik6ni;1x(ewuz q2,9 d3 mrgfu-tyose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body tempe,-(zzx t9w0 uncuq 3;2di6r mi f1gykerature 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 -yh44kzwp wzn ,b 7y2g50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at g, zpznh7k-w42wbyy4roughly 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-/7as;)fat t fd(d)oqc0chqm 6W 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.    $^{\circ} C$