What happens to the work done when a jar of orange juice is vigorously shakesiepa35 /9xevcpy(j c u i q)q/1m9kp7n?

When a hot object warms a cooler object, doe 6: 4ekts 6eu (eaauvc73puwt6s temperature flow between them? Are the temperature changes of the two objek: 36uaw7ct 4e eteup 6a(usv6cts equal?

(a) If two objects of diffeu2smg *o3z l)8rn8s28 fv-dg*itcc xqrent temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internlm*8 8c vn udz*3xgiqso rg8f2)2tc-sal 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 tro+y9qakh+i g8eg9z8a p-)njyxpical plants grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering tqaa)n egy8i9yh kg 8zp++9- xjhem in the evening. Explain.

The specific heat of water is quite largm *ug7adkctejv;0dx 9-t i4k -e. Explain why this fact makes water particue; 4jg-iku 9dv0-dak c7mx*t tlarly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay c bjdl5)n6 rph s8mkgs77gi(g+ooler if the cloth jacket surrounding the c+s)(7h5lgbpijn m78sk g rg d6anteen is kept moist?

Explain why burns caused by steam on the skbyxx t ge01epakq8. kl2 n i2z-o1r66kin are often more severe than burns ce yq.8o -kknz pxk6l1xbtre 260a gi21aused by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the rbb2am h4mw0d 7 oru19concepts of latent h0rd9 a2r417wbb oummheat and internal energy.

Will potatoes cook faster if the water is boiling fastete7t6jk k+dj: ,*x htz(r hye-r?

Does an ordinary electric fan cool the air? Why or why not? If not, why use ito5ud; 3qz)dso/:kv sau1 g (vq?

Very high in the Earth’s atmosphere, t/;u9d zi he8j hw8oz*-tha+h ehe temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering th36u + s2srnyulemselves with snow. Why wouldrns +y6u2 sul3 they do that?

Why is wet sand at t3x*m 0plfljm- he beach cooler to walk on than dry sand?

If you hear that an objectht0a6g:(uq zo has “high heat content,” does that mean that its temperature is high t:z6ouahqg 0(? Explain.

When hot-air furnaces are us netza/w3ee1k (s(lx7ed to heat a house, why is it important that there be a vent k (zee(xtl7as n31e/w for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are somo e(o:4 q/hza04 )hcbux8isuzetimes reversible, so that they drive the air down in one season and pull it up in another season. Which way should you set the fo(u8uox): /04izh h 4sazq ecban for summer? For winter?

Down sleeping bags and parkas are often specified as so many9)53-ypmw(y xnsypa3rtj,ncrx6c (or.p. kq inches or centimeters of loft, the actual thj5 3k rp xy(.(.yt9oq w mrc)pay,pr3x6n n-csickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that dy)8*ftz rb+ryl x( 9flooks like a series of f8rx+zffytb* r9l) dy( ins. Why is it shaped like that?

Sea breezes are often encountered on sunny daysheibw i.q gy0:xnx2deid v1.i8 zvi4z +x)3w9 at the shore of a large body of 8wi)xvz v0yih.1 d92z: i4ig+ ind.q3exwbexwater. Explain in light of the fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow is often .) qt7tn4ddwjk) t*m kcooler than a floor that rests directly on the ground (such as a concrete )kktjwq .4nt 7dd)* tmslab 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 th.2ep (tnww9 8z:/3 ghvwemlkue shade. nugw:3v8wel(k2z9 w p.h/ met

A premature baby in an incubator can be dangerously cooled even when the wb6 :;cmdhp: pair temperature in the incubator isb::hwp 6p;dc m warm. Explain.

Why is the liner of a thermos bottlde2zoos*uk wij 7 * g0h+f63noe silvered (Fig. 14–15), and why does it have a vacuum *2s uihf+6wz*oonjg3 7 kd0oe between its two walls?

Imagine you have a wall that i7qw4tq oij6v* s very well insulated — it has a very high thermal resjqwi* q 76vt4oistance, $R_1$ 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:ka /vxeau(4x*ex( vhklzu3 )seq 60l the following processes: (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 three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heaa q6(zx kveev (0 l/ ulas4x)3xke*h:ut losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece ofw 6 9 pv7 j3z,lpym5ykhmt1nwo) x+6npx5 ggd+ shiny metal. Yet the wood feels less hot than the metal when you pn+,t 6 mp 3kym+wwypz1v5 jp9d 7hn)gxgl 6x5oick it up. Explain.

The Earth cools off at*hy y i48e4ahllf:. hz night much more quickly when the weather is clear than when clouhfa4l yy h.l:8*i4eh zdy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Exjm ko+ko;, txen*. a1nj-ymh0 plain how it can help ton;,e0m. -n*oxjmjh+ya okk t1 keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme3h6ge 3 w5noz0mmhhf 0 temperatures than inland citieh033hem5 ozhmfng 0w 6s at the same latitude.

  How much heat (in joules) is required to raise the temperature ofc.v6jf7dqz 7f 30.0 kg of water from fq67j.cd f7zv15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is i md ()vbs0o-rbufr :z.nitially at 10.0.0szbm-r fudb):vo r ( $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes aboutz kw7 d1b1(q;wcl2jvh 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 (Btf uznxxq uhp/d9t*ss v m0 c0)y15:-xtu) is a unit of heat in the British system of units. One Btu is defined as the heat :xtm1sx 0yz0s )-9tpcd/ fh *vxuqun5needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gez0 -siq +qvwq*nerate $32,000\,kJ/h$ 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 long it will takehdp+f5og-r0ejjrw4q yllr8u8c2 *b ) to heat a cup +cyrgo 0whp4-l5f2r u8dl 8rbj) qe*jof soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used gd7zk 4v21- 0fdbyfmzto bring a 1200-kg car to rest from a sped7z2 f0 4mvy1d b-fgkzed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heafp5wb.+7e qhpxnv/yjg s)hvv )23 fm2t does it absorb if its temperpw+pv/ 3eqhhv myfx.ngj5 27)sbf v )2ature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific ,+wkanwd b:0c3e4svn 5shyv/ heat of a metal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal fr hvcy4nss kv:/ba0n3+wd 5 we,om 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water mqm *a9w9y1jhexperience the same temperature rise when they absorb the same amount of heat. What i9yq 1 jwmmh9*as the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21x)z ry:k2o ; b3.vvedw.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 equilibre 9sp, q35whvn(1v(jnr id dv7ium 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 (massl7t xq 3qrc;9 j:f-xtv = $0.4\,kg$) 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 heat4dm,wqov 7 h(xdb 65g(gsa yk2ed 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 av3yd8p(wx0h a boil 0.75 L of water initially at 8.0 yvph0 (w38dax$^{\circ}C$? 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 obimu;d- d72r(08ki x;sewomf s +h3yz f 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 imssi;m(r0fudbyd e8xo z2 -h wik+3;7 n 2.00 kg of water contained in an aluminum 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 iro 2i*7*ar pfsz8v ptc2an 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 hammer 7 6cw;s .vef-t9pwdwe has a speed of $6.5\,m/s$ just before it strikes a nail (Fig. 14–17) and is brought to rest. Estimate the temperature rise of a 14-g iron nail generated by 10 such hammer blows done in quick succession. Assume the nail absorbs all the energy.    $C^{\circ} $

  The heat capacity, C, of an object is defined as the amount of hefgl45z m7.mjzfi c, q;at needed to raise its j gz54lfmmziq .c,;7f 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 of silver th:e- y)q6sq htw uuiim. v6g,1qat 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 building. ie7nul h9p8b0 vynabd d3*:h-: ivd)rIf 65% of the thermal energy produced when it hits the ground is absorbed by the sphere,ib3hb nldr*nd98-y:)d07 pv i:ae huv what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by 2l0zua:lz v.bevaporation of water from the skin. How much water has beenal. zu 2vz:lb0 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 insular jreoyt 57+ wsy:)8blted container of liquid nitrogen. How much nitrogen:r7s 5)ty8bwlej ry +o evaporates 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 from the freezer at -8.5 *7 5cf7m1,m1vtcuh *bcyhhuz $^{\circ} C$ 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 kb2s(0 npk*h) a3c8 br 9dctjvbg of water at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consumes 8.0 L of water over the xz4wv8vtz2w 7w 6b(clspan 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? (wzvw b8lc 26zvt (4w7xSince 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 10 b+yf,cnnh(4 c0$^{\circ} C$ 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 merz o-itffsz76ur7w,,17 p2jo 4 ds pexscury 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 p ky)m2lqa7l4 -cy3ej+h yf1gff2 za 3at $250\,m/s$ 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 mom5ve)egz(8 ;7v cabvb ving 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( ss o:ttzi05gv n*p* .cjne*x19 rmvy-g lead bullet that was stopped in a doorf9. c g*:jeo *mss zy0 vn1p5vxnt*ti(rrame 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 diametegz,u qu(2bqzp+i kg3. r 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 Exampy s g3q-cz-;gsvtrt+: r7m*ca9.q jtwle 14–10, assuming that there aqsc ;+3s 9twytjcv -7g :qt. rramzg*-re strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated;t0ame e06zcjeh8e /t 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. Suppo)qj9stxw0vq8rj c ) +ose 200 W of heat flows by conduction from the blood capillaries beneath the skin to the body’ssq j+cq)0 )8rwtv 9oxj 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 4v8t)y.m3cvs s/yfry5 nvl0f,.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is at 3.y,/cts3fvvyn mlyv0frs8 5 )0$^{\circ} C$, 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 bloc 3;pj)hvtvhw c*a25nv k 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 are5t+s6n;uel px attached end to end (Fig. 14–18). The copper end is placed in a furnaxs6en+plu ;5t ce 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 th nss2 pzkz8dr nx.+nkv(2g ,5ue whole Earth receives energy from tgn5zpu(n8,zsk d 2x2.+skvr nhe 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, b) 0ut*5r6lxhj* z syewhich is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperaturehxr)zy5 tjl bu0s6e** between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house comhoj: +0na;josy(/zqs e 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 such a wal /sjyo+s an0:o; hqzj(l, 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 separate bpw+-k/ry)mcutu:(: t uk1 yq;y9t wod by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction icyy)uwbk p y/1 :roqu-+mt:ut wk;t(9s 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 ke mda pt 4tzwr wc9o89kg;5i v.xz9k*3e+,qt rg 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 vaw0ydpq +080 l; vwwh:)dbshkg 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 contab vf0gfc84lv4pz jln5 0e nx+0ined in the world’s oceans, estimate the heat liberatvx0p 4fbl8fz0 4enn50 c +jvgled when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed bloct ea k)k(j* 0dc:kvzj1k of wood with a mass of 1.05 kg. The block and imbeddeddejktk czvjk): a10*( 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 in:93hu4s5d9 x gmv js .*x04m srtvylqcto space by the Sun, assuming it to be a perfect emy 49:xs 94rjglvvms35 ucx*qhds.mt 0itter 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 activityw)m baz9h 8n0y, 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 rolls off the top of a cli.+ a jq:q8i ddtxnaji+:y 26uoff and falls a vertical height of 140 m before a2ody6j+i n tx .j+:uadqiq8:striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water initially at ordsqs. ac20m5he,+l a::6qiw lk(k b2.s0q5d k 2(s,:k6q obcrei ha+m:alwl0.0$^{\circ} C$. 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 withgp6- qj;)y9n-ahfnvbebh 9a t;fz2.n total surface are q6hp tan ;;n)an.- -ebhy9jz9gv ff2ba $1.2\,m^2$ 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 hag3)*p dczp92huk k+. w4yi 7h/ixxwxqs an 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 heat can be conducted frommes znet.8a66 the interior of the body to the surface. Assume that the thickness of tissuea s6t 6e8nm.ze is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thick (assume conductxrh;m-ox/c .ad + u)skivity of air) and area /-uxks.adm ;oxh) +r c$410\,m^2$ 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 at 2:hjqk v4vgn+f 3v 7. trpeey6b.wvcv/jt(k*$220\,m/s$ 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 7sp oen- 8usq0t x/lockg :(:e(a) in Problem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the e(o8qp/t cg xoesk:ul:sn70 -leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when*hpqn/p 6in 2jdy2. dw it enters the Earth’s atmosphere. If its initial tempyd62njn dihp/q.* p 2werature 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 t4 t5 x6,jigsgg9; mqnewyj8 2Earth’s 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 soft rubber ball at a;,g:va(fa-oye l*n sc xl* ;ks wall until they are about to drop due to dehydration *na;,*xevf a ;ss:ygo lklc-(and exhaustion. Assume that the ball hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masses of i5x / rv rotnynon6-+-fce at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conducx6 ikdtmyxi29) ++d8g -qxypwtion and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop fromw)8yti 29qyd6d+kxx- xg+imp 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 tsa1:ytv9d yuaim1e8n o2 t80 nhe 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with wn9d8ato e0 :y1smiy 2utvna 18ater at roughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a 60-W ligha6rakecmmq*j 6 );h +ktbulb 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.    $^{\circ} C$