What happens to the work done when a jar of orange juicr(vvma;bl88aard g w3*g2 a4qe is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? A ecsx 1xdn bya,.3t(:qre the temperature chanaeyxt ,dxqs.cn3 b(1:ges of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will hea 7g4*ms w)y.xh* lqi3qto/dznt naturally flow from the object with higher internal energy to the obj*4*gdi) qnsx qowh3/7zty.lm ect with lower internal energy? (b) Is 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 tempe zt-ag1q kxq- )8bq37oj0l gnlrature may drop below freezing a few times in the winter, the d-8jglo3 t -q)lqaqgnbz 710xkestruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this farobzcgws5yd6jjzap50 qg, mg5w92ht(u9c 6 6ct makes water particularly good for h5zwwj( z9,cm u2g6r6ahqcy9opt6g50 gd 5sbjeating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler i6:li3:9se( rafo;gu damn(rf f the cloth jacket surrounding the ri;(ondmus:l6ea fga r9f( :3 canteen is kept moist?

Explain why burns caused by steam on the skin are often more sip p.e:kq hoik uva *;o55/z*qevere than burns caused by ouk:**pah;v/k.pziq 5 o5qei water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) whw)s6;z*- tntyhs;0 vp wyi u lg9gq ow*deg3+)en it evaporates, using the co 0g3+;;lw ozg*9*nhsg )ueyqst p-vy)dww6tincepts of latent heat and internal energy.

Will potatoes cook faster kr *iq)n8ogj5g s7lf)if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why t()aow9. h:qq .5ulnifw qt8gnot? If not, why use it?

Very high in the Earth’s atmosphere, the temperaq l68lnivwj 09ture can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survic ,lx y8brn0gv .mh(f7ved by covering themselves with snow. Why wouldyg(.mh8 b0f,x 7cn rlv they do that?

Why is wet sand at the beach co ztcw bltm/h:0o p(t(9oler to walk on than dry sand?

If you hear that an object has “high uf :qt3 6w: 934dlu4orq- knrj4atsriheat content,” does that mean that its temperature is high? Expla9tnjtq r k:oi63r r-d44lfwsa:34uuqin.

When hot-air furnaces are used to heat a hous gcl ,e p0mb8o;3icwc4e, why is it important that there be a vent for air to return to the furnace? What happens if this vent is blo83ie; oc,4cpw0gl cmb cked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down iup i (v9*mm eqmv04p4on one season and pull it up in another season. Whicu 4i(v0pqmmopm* 4v9eh way should you set the fan for summer? For winter?

Down sleeping bags and pary v1mo 5uych qw2sorp00)2k.e kas are often specified as so many inches or centimeters oh.wv0py210 52 me orsqy)kucof loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on uea0xpv e; f);:r zx)utop that looks like a series of fins. Wu:0fevx reu ;a));zpx hy is it shaped like that?

Sea breezes are often encountered on sunnppm4yw e c(v39y 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 thatcew m49v3yp p( of the nearby water.

The floor of a house on a foundation under which the air can flow is often m(3(sh.jpo- y rh(yn icooler than a floor that res3(m-no hy p. yh(sirj(ts 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 readings are always taken with the thermometer in t *yx.i6dnlwx+6n t6 b2(c jpbthe t2 xwnb(yxjd +*n. ipc66lb6t shade.

A premature baby in an incubato5ra e* fls2l1pr can be dangerously cooled even when the air temperature in the incubator is warm. Explairl afp 5s*2e1ln.

Why is the liner of a thermos botem++(ld k 2dhltle silvered (Fig. 14–15), and why does it have a vacuum between its two walem2+ dhl d+kl(ls?

Imagine you have a wall that is very well insulated — it has a very high therm: *3wrpj-j5fuhw md;woq4r;eal reso-ufj: 5rw 4q3ej w*prh;d;mwistance, $R_1$ 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 fohd4ly wa 75bfpk)1f7pp6dy5q llowing processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass p6ql7pf51 yd f)hbw4 y5pa7pkdanes; 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 heeu i )xr,jj+r*buf :h6t;ah)n(fmk v9at than a piece of shiny metal. Yet t;ef6n) +,b(rh ui a*kxjfm:9tuhv)jrhe wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is clewyh )5ut ,iqnd( d6+7wv4ovp har than when cloudy. Whw7 vdnwu5po+qt h,d 6(v) 4yhiy?

An “emergency blanket” is a thin shiny (metal co zwhof*(*quuy*(s9mb ated) plastic foil. Explain how it can help to keep an imuz*w (*u9m byhsf(oq* mobile person warm.

Explain why cities situated by the ocean tend to have less ext4f/hrp.+tjma reme temperatures than inland cities at the same latitudth+p /j 4.rafme.

  How much heat (in joules) is required /c y s,pomugx+/9g uog1 +3n 2mjjio/dto raise the temperature of 30.0 kg of water from 15m+/ j9cs3xm/gooujg/ny +ogp, 1d i2u $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raisek:u a1f6h,b /bvj bl48wawk5h 3.0 kg of water that is initially at 1l bw4, b/bhjfh: kuk1a 86awv50.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about mc;u x -kv/8pga bvy5qtc;15d 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 unit of et6 s8/3 bf skv ujmed+46qx2p)y,bou heat in the British system of units. One Btu is defined as y48 ep6sk ,d6vuf o)xuj3tb/+bsmeq 2the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gener (5gp rbv,9r,cnpgv/zate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heat6(n wrg/ jztmasap.z,5 63 erler is rated at 350 W. Estimate how long it will take to heat a cup of soup (p j3r6 ma.zzn/e watsr 5(lg6,assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the y h 5k;0m.u jsoum*k6cvfpgha7/29 frbrakes are used to bring a 1200-kg car tog; / 5mv yhuh2s omk*kr7f.p6j 0a9ufc rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling s)zy,d- j wwbqcl0.h p1ystem holds 16 L of water. How much heat does it absorb if its temperature riz1bw 0p -).ycjwhldq,ses from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is neede-vufv hfsv1 72d to raise 527vsf1 u- fhvv.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum,r 59*c zvum,fe and water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: See Tabc59mzrf *v,ue le 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rep au,vncao(tnv+p: o/xp -d06utcg8 4ads 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 when a 245-g bloczu-v z)0bukw ;k 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 horseshoe5brs3 um 7 xb*ll3bjqz2f i)3r (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 substanceicxi,;,w (yr ngbz 9l( 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 qm 7*6uq j/e )oo9yr7ibjls c5bring to a boil 0.75 L of water initially at qjmb*s uoyr5o7lej)i/ q769c 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 o+03 kq7a(djdz (reasxq,v w.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 osa0dqvxw(e (k3,7j+.dzqra calorimeter cup 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 at 180x82u hac; iaq7;d,rqbo j;:ha $^{\circ} C$ 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 a -se.-h w7fp *)ox u mz-aqls*1yj9so4xko0ci 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, Cja74- g k:yrsw, of an object is defined as the amount of heat needed to raise its temperature by 1 s 7jrkyw:g 4-a$C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melt 16.50 kg of silver thats eap;h63kxed0fg(. z 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 buildinus1kw)-.xydrrzj r8* / la sm(g. If 65% of the thermal energy produced ry-k8dl/)u mjr w1z.(xars*swhen it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off/ dzepmg/q5*b2b* qqb 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has/b qd2mb5qq/*gb zpe* 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 into an insulated containnjg :uq(:qub82 vp1 lcer of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent j8 cupgqv 1 :(qu:2blnheat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from thep*;p, fb; ):eak ctjlx 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 contains 830 kg of wat8xpby o9h3wt 3er 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 8.0 Lwje-lkl (1 2n(*+y cjyj9xygr 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%, most of the energy consumed (2e-y+r( 9w*xly1jgj yjc n kldoes go to heat, so our approximation is not far off.)    kcal

  What mass of steam at j m wb5gx +qfg/*ol1 ws2:jc-p100$^{\circ} C$ 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 m qs* .z5qxw ncgfr3u24ercury 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 4bwpz2i,w /e+x ct1jg 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 movj+dh-h.fy*1i s2eecx hn12iging 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 investigatorfnz03bdz e9b8 notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bfeb n90 z83dzbullet 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 diameterox;w)*yqz;8cqf ku.p of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduction in Examm85o7knb vz; zple 14–10, assuming that there are strong gusty windok 5v8mbnz7; zs and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivit66z 2)3vgzxzy1 miwpey $e\,=\,0.35$) 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 fr,y/ hapd*7jspg)y g:j om the blood capillaries beneath the skin to t */ 7ayshy dpj:gjp,)ghe 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 yj9e4ff7:+ lksyg) x/v)x uas4.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbxu xf9)av4y/kl+es 7:fsy)j g ulbs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun+d q. eib0;-n,weqdum to 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-sectgdpp*8 m,x5 zw nap4u8ional area are attached end to end (Fig. 14–18). The copper end is placed ipw58zn agd 4 *x,pmup8n 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, estioaea,3en.k3 sp i3 s4xmate the rate at which the whole Earth receives energy from thks4 a3o 3. ix3pe,senae 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 dissipated through a glass .ov/bvkltrk r 5we48)p; 4vdwx+d/ fwbulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature bervb dftx85) +ek lwd4.v /4r/wkpwv;otween the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly fr+r 9ydf8ba+qafn c2 i5om 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 sun9fidyb8qa5 f + +arc2ch 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 space, Fmmbn/2 7xy p/jig. 14–20.2bj7/m /mnyp x (a) 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 lony.iwem/ +tc+ x (1j/h snrltz5g should 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 kg of lah ;ciz7720.0dqoe x 1pqxqcf iquid 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 c8 m 3w+j*2io/oswtlr contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the o r/l328swt*ooj mciw+cean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed bla-ev mf+mv2j.ock of wood with a mass of 1.05 kg. The block and ivv.-m2+emjfa mbedded bullet together absorb all 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 radiated into space by the Sun, assuming it z(cjapv4,zo24dl3e c /bf1d fto be a perfect emitter atj ec34pv (z/z2bfdfcld ,14ao $T\,=\,5500K$ The Sun’s radius is $7.0 \times10^{ 8}\,m$    $ \times10^{ 26}\,W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5 \times10^{ 11}\,m$ away (Fig. 14–21).    $ \times10^{ 3}\,W/m^2$

  During light activity, a 70-kg person may g99ya9 fx y5fsefp6glnl:2 vd8enerate $200kcal/h$ 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 o86ua kcqk+za2fe8;p vf a cliff and falls a vertical height of 140 m before striking the ground.2 zpe6ukvfaq8; ak+8c 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 pail of watnlbby qr wc az6f0d: :5)c:a/y:vs4fler initially at 20.0:dbl q:ay 0c:bf 45vs/n:wclzraf) y 6$^{\circ} C$. 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 with8: wvm0foyjp 6 total surface area 6jpfym vo8:0w $1.2\,m^2$ 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 zhh+*7 ;qkmq h9n4bsz average metabolism rate of about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which hecnrd: .-gt:q3 velh2 zr dpm9+at can be conducted from the interior of the body to the surfacer+gm3e.2 znd:pq -cr9v hd: lt. 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 1pzwh:h f/d. 9g7.5 cm thick (assume conductivity of air) and fh9pg:hwz/ d.area $410\,m^2$ 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 trave,v.w /or:s4 nn4e x2sceu ql3lling 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 rf -aqf * ,+ue-+imt:seuski;w/ vjl9zadiation from the leaf to calculate how much water must be transpired (evaporated) z i-msvffw,; jue e/+s+:tl quk*9ai-by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts wl2 w+xzz8jm.4 xs e5xxg2rdm0 hen it enters the Earth’s atmosphere. If its initial tex8x+ rlzmx. z0x dmjwsge2254mperature 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’s crust increases ab f2ek-9mh ; nmlamm 676rk5ap3tqix. gout 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. 1 lz 078ie 9m ga66altly;ww0hq4–22), two people hit a soft rubber ball at a wall until they llqt6;aw0 iwa l9m 68y0h7zeg are about to drop due to dehydration 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 rqzbsfdpbkw8, ia3i s+v)5j* ,bjd-p9 esult 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 conduction a/5zymflx dd bjx,msl1h ;06m8 rjp,7m nd radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drhym0,8djr1sxp5fdxj,m /7mz l ;lmb6 op 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 gv*r lr/g,d: bvx2wq2 (185-L) water heater. This suggb gq,2/xgr wlv:2 r*vdests 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 6ni;v6tt: he 0:+rhrhk 0-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.    $^{\circ} C$