What happens to the worktv 5h/ ywdv6e4 done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooleb,h6 rcz5 x,hqr object, does temperature flow between them? Are h,bzq,5hrcx6 the temperature changes of the two objects equal?

(a) If two objects of different temperatures are placed in coe i03/o3wh ahwntact, 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 h3 a eiw/3ow0hobjects are the same? Explain.

In warm regions where tropical plant fd9d y)+eaa/q,g1mdubi3dq 4+kg0zqs grow but the temperature may drop below freezing a0dkd iyfgqb ,e/dam+uq4+)zq1 ad 9g3 few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of abr+ w:j/i rzdgvg)a-9 f/( whwater is quite large. Explain why this fact makes water particularly good for ha f:j+v/dgz-/9awrw gir bh( )eating systems (that is, hot-water radiators).

Why does water in a metal rtide0km45s0 6(dsor6pu 8p ucanteen stay cooler if the cloth jacket surrounding the canteen is kept m68ikot 40esu rs5p0(d pru6m doist?

Explain why burns caused by steam on the skin a: osn3ek w;sq,-jr5ijre often more severe than burns caused by water ersnj 5wk -so,ji:;q3 at 100 $^{\circ} C$ .

Explain why water cools (its temperaturez)m6p 7fiv tf7 drops) when it evaporates, using the concepts of latent heat ap6mf f7vt7iz)nd internal energy.

Will potatoes cook faster if the water iomr-gx cf.f+m-6f v 8ys boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, wx2mdyt.al :sd vp6+ 4uhy use it?

Very high in the Earth’s atmosphere, fr m n5ww4 0a-5lz3ebjz/quk /the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic exph k4-q 7.q xltc.n7x4mkdn*un editions have survived by covering themselves with snow. Why would they do that? th.l47xdk*qqnc-n47 ux .nmk

Why is wet sand at the beach co 0k5xq9 dyy-q cz i0q7cvm3*3z kaf(mloler to walk on than dry sand?

If you hear that an obje4ght/(c+0 rrvxpq (i2 c.zzlnct has “high heat content,” does that mean that its temperature is high? E/( nrzitvlxg0pq r2cc( h4.z+ xplain.

When hot-air furnaces are used to heat a house, why is 4 y64n8x2b q44tbv t;4bk+rcp jgxz vnit important that there be a vent for air to return to the furnace? What happens if this vent is bt pgcr+xy vqbn bvnt4 24;z44j4x8k6 blocked by a bookcase?

Ceiling fans are sometimes reversible, so thatjg42sl, tpuejo 5+sk- they drive the air down in one season and pull it up in another season. Which way shouls+po 45u, jjsk tel2g-d you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so ep9t psew )mr09bdd. r7v8as1 many inches or centimeters of loft, the actual thickness of the garment when it is fluffedrr se)twpp18.sd9 aev0b7 md9 up. Explain.

Microprocessor chips have a “heat sink” glued on top thatu h*r+ nr s1*1ikps/uw looks like a series of fis1k+p1 *uhs nw r/*iurns. Why is it shaped like that?

Sea breezes are often egd/v;go wt5l8j85smvncountered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more8w vd t8;mg5vso/lg 5j rapidly than that of the nearby water.

The floor of a house on a foundation under w70rg ah .nmjg4/kavj0hich the air can flow is often cooler thamj./nahg0 g407krv j an a 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 readings are always taken with the thermometer inl8;i 0mvgaxj-l ;wg:o the shada lmijlg:;;0o8-vgx w e.

A premature baby in an incubator can be dangerously coolex/z:;k1ygfce d even when the air temperature in the incubator is kg :ezx1f;c/ywarm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and wh;s:qlwlor f4. ,q gl;ychy 0ir93d i3dy does it have a vacuum between its two walls? ;rry9s40i df.:lq3icolw,h; qg l 3dy

Imagine you have a wall that is very well insulated — icn, i44 2r7sa(jty uvct has a very high thermal resistij c c7s(,t2a4yvnu4rance, $R_1$ 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 thesbijd*+ nnjq6 (e3n e02y qk3x 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 curtdis3qbk+ene(3 yxn 6 qj*02njains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piece of shiny metad 12)om lpcl0*5y/r mfx(pvqwl. Yet the wood feels less hot thp mlxc y2v p/drq(0m 5w1f*lo)an the metal when you pick it up. Explain.

The Earth cools off at night much more quicklv feb*o o-w6q 3,vep)gy when the weather is clear than when cloudy. o)eebw,vq6* g p o-vf3Why?

An “emergency blanket” is a thin shiny (metal coated,yea)p jqt g2vw n3ax p3+8ul4) plastic foil. Explain how it,jl +pg2uqxa e np8 at3v4)y3w can help to keep an immobile person warm.

Explain why cities situated byfa ;y0+wih *it the ocean tend to have less extreme temperatures tha* ii ;0wf+tahyn inland cities at the same latitude.

  How much heat (in joules) is require+klkdz1uu*nrva s c,c5k.tl g 3vx0*,d to raise the temperature of 30.0 kg of water from 1,d., *rn1 utkx vs3 czulvglakc0k+5*5 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat l(lxzgr3. i4(+oe(7 xgs*g (ohstisb raise 3.0 kg of water that is initially at 10.0 o (7g4lob( (hsgz stle+xxir.s g3*i($^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal.cejh st/ll2.3kdlgs6 2gnv1 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 u 9nk) o9rg,xi -,knkkinit of heat in the British system of units. One Btu is defined as t o, k)9n9ii,rn-g kxkkhe heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can geners:nm0ry:/mnfl f. ,lp ate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated a3guzz5 pn.np e-;*ojj7bb w c-t 350 W. Estimate how long it will take to heat a cup of soup (assume this is 250 3jbz-ezobj5pnwp g.uc; -n*7 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated1ejx/8flpizq6 /: fhf when the brakes are used to bring a 1200-kg car to rest f/xf 6pehf1 lzj8/:i qfrom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water.)j us1e m7wv8nw 5n4po How much heat does it absorb if iv8j5uwnw mp17n )4eosts temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of :h 1:gv lzvi8z: g2gtta metal substance if 135 kJ of heat is needed to rais8vtgi2 g::: gz hvlzt1e 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature rise whp:q;9v)fas d ;ay rs8ven they absorb the same amount of heat. What is the ratio of their ms v;d)9 aapf8qs ry;v:asses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermome q8j(-p8dqnl3 xuy :pkter reads 21.6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibrium temperature whepuf wpc((p9z6q55l 4nibc0 k in 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 e 6g;7njt5ogl (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 d-n:79thjmg*i c7sfb substance 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 coffeepthz:x) s n,*tek9 qhn)c -fvu/ot to bring to a boil 0.75 L of water initially at 8.0*kuh nfv ) ,t)qcse-t9nzx h:/$^{\circ}C$? 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. 3x3vy7 zv.n; f.yiap d:5xacgq:rh+ rxs9 -ut 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 containxxf:p i5rsu 9 htyvq:da .3+x;n3v y-r.za 7cged 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 iron t*h c5d d:0kssat 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 hammejg yk)oh0p2ca+rtc,7j. k x5pr 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 th( ne65 :1,.;:fmjns x c oujlpuei)ioke amount of heat needed to raise its t(.5peck, noml j i)fxe1 6u:uno ji;:semperature 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 initi:jnm/2rh ja.wmryv6- ally at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high building. )fsgjfqy0z pbm)wuhw4 t/*v)zv 94 c0If 65% of the thfp) z/4*z) y0tv0q4hfwg )u 9wmscjvbermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min b)a :avw eeutp r1m3z..y evaporation of water from the: 1ar 3a vp.zeetum.)w 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 point is dropp)5/le tqqy uq0 5k xxtm6;epd,ed into an insulated container of liquid nitrogen. How much nitrogen evaporates ;e6qm/ t)5kp,xl eqdyuqx5t0 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 s7kvu 8 hn7,nm n 7873oth pph:jp1ljothe 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 cont ldp0/ba;3e5(mvm5ncs qgq)h4bvb8iains 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 consumes 8.0 L of water over the span of5/ht 6gocad5x zhkl 52 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 does go to heat, so our approximation is not far gok th5cl6255hdxz/ aoff.)    kcal

  What mass of steam at y.t -ntey(y7f100$^{\circ} C$ 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 mer-t c4k h)c5 (f,p-3 yoo2ogz ozmg1qdccury 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 at r d wlrm r-vt ki;14f+adb7 nz,*1j1md$250\,m/s$ 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 moving et9 4ok8i0qi8 n z)kpgat $6.4\,m/s$ 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 :)jcbnkxy ll7o )q-+x8.2-g lead bullet that was stopped in a doorframe apparently melted completely on imx) qx nk-ol+7j: )bcylpact. 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 aev g99t b- mld5r;.czut 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduction in Example 14–10, assuming that tqg dt53c6goaj9q*y p6 +i56 8evfaalr here are strong gusty winds and the external temperatureqea+dr5gapq oti gf63 j*69 a5vy6l8 c is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiatedl tq7/o.9g rkd4iyw *ejl5s2.brw 8om 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 qeq h1 5c acag(u; fpja8,6 qtfvbcn)08agh-:by conduction from the blood capillaries be a6,fcqn8g uc5bf8-c( gjq0a h1eh:qp)va; atneath the skin to the body’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per side, share a 12-co/, i z/u wne/vm :*sc9ezj wc4-n:emfm-thick brick wall. Because of a number of z v cj:eof/ wsew ,/nzm/-4m*u:i9cen 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 block12;patw w ;ij-hgyal ( 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 9u15 f uh84o mczyjf9g(bib4tkh.e .s of the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained 4s.u9bf5o u.ekt (z4cm8j1g hf9by ihat 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 the l di,hh1um, iab na47:z(adh-whole Earth receives energy from the Su m(,h-hdil,h4nauz1 i:d 7aabn.    $ \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 dissipa2f1 7fi b5 vl69l,yrjpctk3dcz dt7m*ted through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces df 37 zk 1yd62imlbf*l, tcj7tpv9rc5of the glass?   $^{\circ}C $

  Suppose the insulating qualities of jizj/*w)ltzr7klya n1* 8g r)the wall of a house come mainly from a 4.0-in. layer of brick and agajky8/ri t l)*zjlznw *)7r1n R-19 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 by 9yt4+z cvxky )gzh;7oan air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by xz;9yo7 zck)ytv 4+g hconduction 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 11utk ozbc m )0ie884l/m.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 f9l3f :)kys el-9f,sq +iwa rfabout 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 thermale9 jordr qe0010mn czo(ra-:l energy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each 9eeoc 0ro d( 0rnrlzqjm1:-a0 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 wmecwhx059q0n1wbx: / hpe) ucood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, thw ebcn91:epxmuh 0x/h5c )q0 we 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 intoovm9e h 5u-+y jv)hub),9xqdkq9hm / e space by the Sun, assuming it to be a perfect emitter ab+9,qv )dy)e /hom-uhvueqh9 9k5 m xjt $T\,=\,5500K$ 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 persa *yhsi1+ bkva4ype+,on 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 db4b )sshp 3:s.j c7s2lfeuk4a vertical height of 140 m before striking the ground. Estimat4pd.hjs7ssl: cb4 f)kbe3 s2ue 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 k 9lbt9(9ts vl2.5-L insulated pail of water initially at 209tstb9 l(k9vl.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 wearey3 2lv;g,jkh 4w mq4 k5qo)lzs a goose down jacket 3.5 cm thick with total surface are44qlml; jg)ewyk z 5q ok2vh3,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 rate of+1jmb.;s 2qqmj :zptugs *w t: 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 interiod9i8cam( iuf 7r of the body to the surface. Assume that the thicknes(7 iad9u8fmi cs 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 thick (assume condui 6jrk+jemn /c9 ijvd,9:eo0uctivity of air) and v m9jjrd 9j60:+unie ec,o ki/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 traveling at bev3d* cb 94jsjhayh( 6zxmj3(p7 py* $220\,m/s$ 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 radiation f/07b3i y plmweg4y;a j(hf-uzv sy mu-w j(n4*rom the leaf to calcula- yv-yibu0g ;jls73w4um e*zhfy4 /njwa m ((pte 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 tk, yrq*6 d : 0(z,rpqnsto8gfwhen it enters the Earth’s atmosphere. If its initial temperatu0 o6r, 8ksd:zp(q*n,rqgtft yre 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 increas 84q3rt34 tvep69 fv1r rlrimzes 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 peoplen 89vd5 wq5ztc hit a soft rubber ball at a wall until they are about to drop due to dehydration a 5wztc 5dnv8q9nd 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 fin3iw+ )p32ttxp zy)9 rhnlo 9pyal result 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 and radiation6(rlc fu9a g1c at a rate of about 2c6g9a 1c ur(lf00 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, there is “no hot water” leftvy 1*(n y/fpz a(obga9ve.sd2 3jbgc5 in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at rou2*yzg dj9bays (e1 3nvf.5ga opc/b(vghly 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 lightbulb rp8 ux4n4a-ibn 1q9 3moro(c vis 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.    $^{\circ} C$