What happens to the work done when a jar of orange *9bzaa)y/eog w/h lpvr by9-:y 4t*j vjuice is vigorously shaken?

When a hot object warms a coolew0ntdr)efv9 ;3 epqw8r object, does temperature flow between them? Are the temperature changes of the two obpq80w w);3nved9 f terjects equal?

(a) If two objects of different temperatures are placewm9bu: 3skt)m d in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal m:t9m)3su bkwenergy? (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 t iw-*/+ jt spo5pupo m5nmxpjle7l2d z-61n2u emperature may drop below freezing a few times in the winter, the destrut-+ po1-xu 25ewj5 n /zmsl2n l*ui 6oppdpjm7ction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat ofjpor6f9exyc3 d4 le*j 3h4j7czgi b )/ water is quite large. Explain why this fact makes water particularly good for heating systems (that is, hot-water r 4op 93cl*63zb gejjj 7r4hficd)/exyadiators).

Why does water in a metal canteen stay coolerel0 ;5*rcm2kj le yn0m if the cloth jacket surrounding thec0 ;e20j yle5mkmlnr* canteen is kept moist?

Explain why burns caused by steam on t2vqg(9op 57aed0d hlrw4a 6b the skin are often more severe than burns caused by water at 100dabp04 9dgt o5wlev h r7(62aq $^{\circ} C$ .

Explain why water cools (its temp sb0qv82tf z3kerature drops) when it evaporates, using the concepts of latent heat and internal ener tbq0k vsz3f28gy.

Will potatoes cook fasypag1xtw pzv*)-6 z- a 7m23tt4xinyiter if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or wi- i:1kxocb),1ypdr l hy not? If not, why use it?

Very high in the Earth’s atmospher+z +ifp7vq vu;e, 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 survived by covl kc9x*r 5hs 33cald5bering themselves with snow.*5b3d kcll 3s5hc9ax r Why would they do that?

Why is wet sand at the beach cooler to walk on than dryl -g*5 cb*fgxz sjd0qvjm.:2o sand?

If you hear that an object has “high heat lxn9k2h7.jc k(mcnmb (s 3p o4content,” does that mean that its temperak. px cbjn9c7s4( n3(ok 2mmlhture is high? Explain.

When hot-air furnaces are used to heat a house0.q6 bzz6u-d e)wzhch0fbxv5i we+5 k, why is it important that there be a vent for air to return to the furnace? What happens if this vent isw6-ih .c05z+e uk v b)eqw5zz0d6xfbh blocked by a bookcase?

Ceiling fans are sometimes reversible, so ts d*z .zm9,oaoi;ic( :k6u wvltdl00 hhat they drive the air down in one season and pull i0*k al,l6 vzu c.9dhio0ds:io; mt( wzt 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 inches or c-u+h1ig0z fpf: 4.l,llw0 e gviyp:jqentimeters of lo iyw,f4f: g.p0j0l l:z pg1v-+i qhuelft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips haveq yn 8o nr6-mmgpea-(6 a “heat sink” glued on top that looks like a series of fins. Why is it shaped r8y-nn-mpe6 ao6 gm q(like that?

Sea breezes are often encountered on sunny days at the shore of a 1w; qwr x yvw.+osm7y3large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the nearby water.7o yxmwvyw.rq ;+w1s3

The floor of a house on a foundation under which the air chns 4q:ptgl 9 7 qanr, dg4ux+1cqzpg5y50 x5man flow is often cooler than a floor that rests directly on the groun ,c dqg:xgam4x5rz7ql90ysg54n1p 5 t +pq hnud (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 temperatuvq u8noq+d r9(re readings are always taken with the thermometer in the d8r+(vuqqo9n shade.

A premature baby in an incubator can be dangerously cooled y-6lsbffyt u, am *nzo: kn3)6even when the air temperature in the incuba6-a:u*n yf, 3kz)ntol6y mb fstor is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), anm e zrq:7pn(/ycqz*2jd why does it have a vacuum between its twnq72: qzzcj/* p yr(emo walls?

Imagine you have a wall that is very we+q iv)t ax/mwp:/8hu rrcqz/u3k(j2ull insulated — it has a very high thermal resistq 8iq/j rrm(zwu kuac/u /+px:h v2)t3ance, $R_1$ 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 follzyqh1;3ix;vwriz9h 9n0- jbrowing processes: (1) ventilation aroundn;i j9z9wyrhrvzhqb- ;ix130 edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than vi(s ;xl0y)0c- 2t:s vekyebs a piece of shiny metal. Yet the wood feels less hot than ssyec-)y0x0l( e ib; t2:svvkthe metal when you pick it up. Explain.

The Earth cools off at nigh4 khk*vf8+w +on 0nsapt much more quickly when the weather is clear than whenvpn 4 n+*+hkfa0o8ksw cloudy. Why?

An “emergency blanket” is a thin shiny (metj6wuilb or bc8/57g,h al coated) plastic foil. Explain how it can help to keewr hi/ 6g u,jl8o7cbb5p an immobile person warm.

Explain why cities situated by the ocean tend 95f/ yh;eu hbzto have less extreme temperatures than inh5eby;zuhf/ 9land cities at the same latitude.

  How much heat (in joules) is required to raise the temperat e 5/-8sd+ye,suyqpeh ure of 30.0 kg of wate,8q h sep/yy+ s5-ueder from 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 ini o*1,d0+txs otkqd 9vsz07dgitially a7 tq*+vx90sdi 0 kg,zodstd1ot 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a day. faa t+6g5s qr6
(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 tqtiu( k ii9wr)o2wqjf-w4 5q6he British system of units. One Biwquqj i(9i4fow w 2k)r6 -5tqtu 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 gedfq4 +9nrzw e.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 take60f4g0ogxyfw)zm 8qw+a e9kx to heat a cup of soup (assume this is 250 mL of w+6 mf 4xgzqk0g)efo0 w8awy x9ater) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes ar :oc+ek l72qr 4kd3un)wxss k.e used to bring a 1200-kg car to rest frol +nwk d3 os)qckrs. xu:2k74em a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How m.4akavku2 a/zqao7n 0-n( oq u69yij much heat does it absorb if its temqqi.ok47a9 au j(6v0u zk oyn2/na-amperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific healf7f)v : uqy1k0p)n96jcjstst of a metal substance if 135 kJ of heat is needed to rais y7q9v)0jfc supl j:skn1tf) 6e 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aqm5 j;0auzt s -jfb+e)x-u0usluminum, and water experience the same temperature rise when they absorb the same amount sajus)buzq -j50- +ux t fe;m0of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21.6 (* wqna)vvk)s$^{\circ} C$ 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 245z cvbn 8:el2bg64ckf (-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 (mass = kxzvx r w1(yey./ :0 bzc /talxwf0*do:v6 6rk$0.4\,kg$) 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 hr;fs3*7sg-.m6z iyf-rv ad) yhg ifa;eated 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 ofsior(t *e/ d :3qtu iw/3s*ofb water initi **/o/u(toi eq:3tw s bid3rsfally 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 conten e(sv4w(k9ofek*u/r pt of 75 g 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 wa kre*efk4(s u/o pw(v9ter 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(sz o50x dbkh andj-dy/q,tv.l -p*n ) iron 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 has ) ie gtiz8f9keb g9v2;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 amobvq.mdph, ,im 7-ffx,n 69xg iunt of heat needed to ra,bi,9h7g6mpfx,m vi. q-dnx f ise its 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 that is initially akhp5ih 2hznqxz4( 8 h7t 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminiump fm +awoqa/w4r8qg 4+ sphere is dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits pqwm+o4f/ 4+ 8 qagwrathe 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+ v-+ix4ymau g qhgk,fbo 9;w5 by evaporation of w huy+ kb;4+wiofg9ga x,-qv5 mater from the skin. 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 po 0mo ;:c:3 -uxfb19xryppcvucint 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 late 1ubxvc9xc:com;upp 3-:r0f ynt 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 f7ttd z lweywc4 t,8bt -,4e7eorom 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 mas8uu,cd7 (ixcys 230 kg contains 830 kg of water at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consume +w+.ibn xr)hqv8z7dr:km; vbs 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%, most of the enev 7:b+)n.m;rwq+hrb xz i8vkdrgy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at tg9-e x-/tasl x7 sr*u100$^{\circ} C$ 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 mercuryx0:n ef*diu z/ 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 atf 31e):o(w dm.qdxo(kso)h eu ez.ca7 $250\,m/s$ 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 movi ojl7,;)j3 q xfaeg2x*a )sntwng 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 note df(0ob j*nl5cs that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact dnj( 5ob*cl0f. 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 a 0x c4ysf2y(ti 2vrwe/do,x 1bt 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 conducti 8hun:/v4 nzppon in Example 14–10, assuming that there are strong gusty winds and the external temperature is: nuhpvp84/ zn -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (is:9n 0- ltlzlw)wk3 oczcc,;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 heio +gwc),d7 mqat flows by conduction from the blood capillaries beneath thecwgo,7d m )+qi 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 per side, share a 1tz-+g ae() o6 pkptk* ncs:4nd2-cm-thick brick wall. Because of a nu n p:a z6-kcdtp(tso+* ekng4)mber of 100-W lightbulbs 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 to melt a arf8 h+ nx jv;)8sfz6fblock 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-sevx +isdiq4b; 6ctional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant6xqb+v4 di i;s temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate at which the wh;x cnlqwbe-,/z 6 :zbfole Earth receives energy froz b:,6ex- lzqc;nf/wb m 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 d yfoa9:it6abt4y+ wsuha y;7x:l li*-rws.j)issipated through a glass bulb that has a radius of 3.0 cmy -s j;ui.iw)+aa96 tlfy a*b7owh 4sxl :tyr: and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wx:/jh p8s-x emall of a house come mainly from a 4.0-in. layer of brick and an R-19 :jm8exhps x/-layer of insulation, as shown in 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 bwbbt*hg 46 6szl1a2l mcbl.o7u6 g4 zty an air space, Fig. 14–20. (a) Show that .hz7 bz64u 6tolc*b4 lwtam6 1sglb2g 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 long should iy0// uym jpyq s -t94gqk(.mwtt 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 abf 3sp6-fo k6a9slzz.xout 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 cijxork) 3; theq7b ;u(rtu 1*oontained 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 ocean water as pure water for *;1 r)7ote; tjrb hkquuxi(3othis estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is mg wj;nlz5ajey77.iqxl/h4 mo* ao76tested 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 reach la6 xqjn;7mhoei4 m.57a7*j lwoz/gyed, 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, assue06j: v;cgr1sk mayy4 ming it to be a perfect emitter agr1s;jca0v ye k64 m:yt $T\,=\,5500K$ 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 genera pm mlw)6(/: )u hfulbg+klc5qte $200kcal/h$ 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 verticaldy- xmdon5xw) t)h * v(t(znb7 height of 140 m before striking the ground. Estimate the temperature r-*x)d(wo7zv(xtny mdbn5t h ) ise 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 lcyc6yymo+. d(bp c:6of water initially at 20.c +y( 6.dclybyo 6:pmc0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick with total surfcx*qq - o2av-e d-c,tface area ac 2t,fqd-*q -ecv-xo $1.2\,m^2$ 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 ha -i0e6o:nymjps 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 from the interior of t6dsww04+g(uli xvu *the body to the surface. Assume that thlui6 wgvd+4x0us ( w*te 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 17.5 cm ubops5 rb615fthick (assume conductivity of air) and abuf 5osr65b 1prea $410\,m^2$ 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 tk 0 dim2q81-jll0 q5bfpgbk.vvdrv1 (raveling 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, tqc6 73rxe/lwh ake into account radiation from the leaf to calculatexe w/h3rql c67 how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it ente+aq(ttad1 s7c5mit+z kgjs0 )rs the Earth’s atmosphere. If its initial temper+ d5k07)aasci(g s+ttztqj1 m ature 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 about 1.o32 eyrxxd82j-xowa/ 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 (Figg7 xvup5k ;/jke)s *cpf11jkb. 14–22), two people hit a soft rubber ball at a wall ubjvek 5;sjpuc1k) 1 p*gk /fx7ntil they 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 result when equal masses o.ow81 c6 mtd.cdz9tkif ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a per)tl0c95iqee haq9b7s: yc4dh5:y7nbdt k/cnson can lose heat by conduction and radiation at a rated/e59ie c9 sa)4n ltcbh5bt:dcyn0h qqk:y77 of about 200 W. Estimate how long it would take for the body temperature 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*ob l l;k;a,jh, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at rj*;b,ohk ll a;oughly 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 gla0ffy)ey 8l4wlp*x0 pdss surface of a 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.    $^{\circ} C$