What happens to the work done when a jar of orange jeb9(/;jj:zx. fca74qqn0 2 ste njoa zuice is vigorously shaken?

When a hot object warms a cooler object, does temperaturedvf i 75h(s+zi flow between them? Are the temperature changes of the two objects equal?sf i( dhi5v7z+

(a) If two objects of different temperatures are placed in contacui:qc 3,t jijp /iw5:f fprh+8t, will heat naturally flow from 5i+uf :fqr3 :chi,8tw/jipp jthe object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperature may drop belov7dm;+5- 58q7 ga2uer:i 4w)t fvjcretr mobnw freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering8m7vw-qcn)ot5 57g teabmu4drj2iver+f; : r them in the evening. Explain.

The specific heat of water is quite le 0,ncg7tnf.q arge. Explain why this fact makes water particularly good for heating syste,n7ct.fn0g eqms (that is, hot-water radiators).

Why does water in a metal canteen stay cooj1 -pcu,ab3ptmw j6b; y6qs/zler if the cloth jacket surrounding the cantm 3;, zb6pjwc1 sut/- abqy6jpeen is kept moist?

Explain why burns caused by steam on the skin are often more severe etq+b+e q (rlvx i)+rpl1 ce+2than burns cause b )rvqq2ie(ree+x+ l+1c+ lptd by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporapdo6 ic*n u afx068+fmtes, using the concepts of lateff dumixo6+80*c6apnnt heat and internal energy.

Will potatoes cook fasterb/dm80+z qk5e5io w nso jz o9a/3ac1 sv.,pqj if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? Ifq/9.e: u )hh xl:ypurq not, why use it?

Very high in the Earth’s atmosphere, the t+ smbec8vft7(lnp60s emperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have surl g l*7imu9f03f5 ryacvived by covering themselves with snof5 l lgfc3m7*ar0y9 iuw. Why would they do that?

Why is wet sand at the beach cooler to walk on thano3pkl dyd:bn r(asxj1* ; i,z( dry sand?

If you hear that an object has “high heat content,” does that me7l2(t7v ,ztm)df :sip .oaobran that its temperaapo zv7)lor dm7tt.(s2,f i b:ture is high? Explain.

When hot-air furnaces are used to he (3fjajm2qx+ mat a house, why is it important that there be a vent for air to return to the furnace? What happens if this vent is blocked by a x+a qm jj3f(m2bookcase?

Ceiling fans are sometimes reversible,nykil bv7l c+wr39 *b7 so that they drive the air down in one season and pull it up in another season. Which way should you set i n97 vl3 r+7blybcwk*the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so.5 wqjs1y r75f 8pa26lmizjib many inches or centimeters of lofty57zq1f mpis852b.aljji w 6r, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat ymk(b4p*i ap 5 wj-wv 2pe5gp3sink” glued on top that looks like a series of fins. Why is bvyip34ew(j a2p 5kmgp*p5w-it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large bo.u 370dyii lrbdy of water. Explain in light of the fact that .3y 0ib7ri udlthe temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which0er .p y16eafg the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab p6 rey1f.ga0e 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 thefpwwagqcd1 kzs, a hk10e+i0+6ogv2zn r3z1+rmometer in the shad cv+f+w +gzq0, isga1dw2hp1zo0z r3 ea6kn1ke.

A premature baby in an incubator can be dangerously cooled even when the aoy/v )rxycm ha6h b y3f*0;5dsir temperatma) yrfb0yh*c v5xs 6/;yo3dhure in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14– +km(qz 2ki5mc15), and why does it have a vacuum between its2 +m5q(czk kim two walls?

Imagine you have a wall that is very well insulated — it has apscw lae9zg/lz ,o*0 ) very high thermal resisl)po*l9a, gscew/z0z tance, $R_1$ 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 windows1sg,y-pvv hp1 by 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 meg1p,vyhp v- 1schanism(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 motex-zj.aez 5i 4 by-j/re heat than a piece of shiny metal. Yet the.-e ajtze4iz-y5/bj x wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at ni wro/:( s dv bm3qwwu1o;-w; 8bewosu5ght much more quickly when the weather is clear than when mue:rbw-wo;(wb d15w3 /qsvwso8uo; cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil.ft y9 6py4h9ed Explain how it can help toe99 46dhyypt f keep an immobile person warm.

Explain why cities situated by the ocean tend to hgl*ypp 7zyf j6o.n vl8*e1+xhave less extreme temperatures than inland cities a nvj.** h+g 8zxl6eyfpo 7pyl1t the same latitude.

  How much heat (in joules) is require eaz35fr(jw 8jpz6)+3 s axlh h0kj/ind to raise the temperature of 30.0 kg of water from 1re8hj)ps6(3 j/z klx + a0finhjw5za3 5 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7ew k :vzc+i7t h+wvdrl4*f*-p700 J of heat raise 3.0 kg of water that is initially atcipel + 4ktwr7:vv*d* hwf -+z 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a day9f h0lsre k7q4.
(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 the British 3wy l/w/n+ ppche5yh hng4oji-f:f+et 6;a+e system of units. One Btu is defined as the heat n /f;6 5 eeyjgy+l+hc4f3/+:hwiape pnw-h not eeded to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gene)dfud;nxhv 8dfi5yxr/oz41 ee156 e prate $32,000\,kJ/h$ 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. Estima6a,ey p 8r/()9awvfn( h xoipbte how long it will take to heat a cup of soup (a6h b) ifx9pvwe n,(py/(ora8 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 to bring a xnw m0xmo/ f r:3t5xe-1200-kg car to rest from a spem/x xr3tmx:n-e5o0 f wed of $95\,km/h$ ?    kcal

  An automobile cooling sys :(5y.oppxgq sy5kedtr ;z7 l;k42enutem holds 16 L of water. How much heat does it absorb if its temperature;yqlp7.2ygkxz;e s5o 45k p r:du(e nt rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance pd4mp ,3jv- brif 135 kJ of heat is needed to raise 5.1 kg of tm3p- jrb 4vd,phe metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience tu29u(kdy7 do:rm wnn +he same temperature rise when they absorb the same amount of7:m k +rn9u (ndyduo2w 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 21.6hch6a h+c)l6i $^{\circ} C$ 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 temperatu6y;n08h x-6sw im fispd)(wqore 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 (mass ze27t,/3k wmnkf.7pprx o.lfe h c( z6= $0.4\,kg$) 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 sc .)sxzi9vjhy3e, n( 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 coffeepot to bring to a boil 0.75 L ontovf(i 9 yq-2w91hmtxm5 k;hf water initialwvi ky q2hn-1(h fxomm t;995tly at 8.0$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy fromkr s l1)60 rsp4g2taqp 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 ip4p10a lg) ktq6r ssr2n 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 zja.yq3. q/lp/ m,igaysvr5 7 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 a speed;8ntso bkpu+b+ q*4yevk c7 j) 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 objectpk41tivv4av*c8/ cbl is defined as the amount of heat needed to raise its temperaturep8ta/clv*kv vc4 b41i 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 sicqnv* dzcxw56/nl 3c7lver that 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 7q94asn9glb )r.wbuc 9l u(ljbuilding. If 65% of the thermal energy proa)nl(l.7rcb9 qbu lu9 j9 g4wsduced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 1 ;vq8l68bwtobad fr8i2zl b( ;80 kcal of heat in 30 min by evaporation2;bv8 t brzql8 w86iabo ;df(l of water 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 point is drj5cn/l3eqba 3s 8h rw73tvq6wopped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has ae qwb5 jl/qn38va sc3h6 7w3rt 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 z8i4gbltoc f7cnguj8)x+ m86 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 contai z d0s/o)ns0yxns 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 waterohn 3tknra(bl9.*gf; 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*k .n lgbr (f9ohnt;a3 energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 100, h)s9lmpwnrtd3zk27$^{\circ} C$ 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+ 0vbf+rajz0 a-z j )otvb-0 rs(9ww,evs6zpd mercury 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 ap8wfe+y0 hse: )oo4ckfx x0g2t $250\,m/s$ 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 mofvbb;3o./9 bh2jcs ovlmi1 k.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-g lead bulle( p8vusz:cz;ma5k; smt that was stopped in a d: u8 p;5kvm;sa (zsczmoorframe 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 aluw 6wc (4ff9id+l 8kpmwminum rod with a diameter 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 Example 14–10, amg/ dl.uon w3e:-q0se ssuming that there ar nml-eguqd o 03e./ws:e strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphee5 5tomjeckkx2u 3q/1re (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 byfp(ra/6h b2 iv8m; nd 5ye+c,.tfnyl s conduction from the blood capi ;dbi+h mffv8 a/cpsntyl6. n y(5r,e2llaries beneath 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-cm-thick qm:a+dvsy/ 3v84fhb i brick wall. Because of a number of 100-W lightbulbs in one room, the aiybfh 348avqiv:+ds / mr is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to melt a block of icev8l4/y+rp flltju ;8h 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 are* gpu1s 9 p.q(dsw+cw)knrus5a are attached end to endwdn(9 1supk+sws) prg*c. q5 u (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate at whs+u8dv3b: 4lrk ry, mvyp4p*xich the whole Earth receives energy from the Surl4u4:ds8 pby*v y,vmx+p 3krn.    $ \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 vd6/g dc1 exw00t6neudissipated through a glass bulb th w00dgvd x6nc1/eu6 etat 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 of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of +w*mum7g 5 2t/wxrmbca house come mainly from a 4.0-in. layer of brick and anmmrb/*m wu72+twg5cx 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 an air space, x-l+ajm0q(bpFig. 14–20. (a) Show that the rate of heat flow through such a window by conduction is g j 0a(l+pm-xqbiven 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 lonbg2 qk0 :1kwr fi9)rv/mc99)xxsrq qmg 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 yu+q t k3- h n1xbs+zkuf-a;ao:bgp4. liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much thermal energy is contained in the world’s i k jk4,3nykh82ci6wno 6fo2soceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approo 42i6k wshn in28o cf3k,kyj6ximate 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 ofb f):zr 8(z8cyliey:f bj6x s/ wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generatedl)z/:xj cb:( e8fr68 zyfysib. 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, assum .gpcus55y.9n ,:widi kevr-l+l/snuing it to be a perfect emitter asi:lw5/+re9ds .. kn,n y5cluvg i-upt $T\,=\,5500K$ 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 genek3pvq:,g j5 6r) 0rst pyfq,pygt/2ty rate $200kcal/h$ 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 of cdtr8 bnq-7k6mhm:5 nvn7u,w f the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rndc8mn 56wrqt7: bv, un h-7kmock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insuw02frtm/0d h glated pail of water initially at 2gh0 2td/ rfwm00.0$^{\circ} C$. 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.yu:g* kx5gp i.5 cm thick with total surface area p:. gxkgy5u*i $1.2\,m^2$ 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 metabedl :fnq(vnfrxuf75+ w1k q3f0vu.3dolism 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 inhwyrz6u34g-rnb,5p ijq d+( w 0ldo* kterior of the body to the surface. Assume that the thickness of tisu i+6ndogb-*405 rwrwpk (3lqdj ,hyzsue 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 conductivity of ge1i r9( h 6yy)4s7 zr,/w fgdqc-tuefair) and ar7(hcgyg sr,w/iufz1f et6d)re 9 q-y4ea $410\,m^2$ 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 travqiahap 8o99q;eling 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 Probley(sbqo es6 0b9r1qn.5u+ etaxm 58, take into account radiation from the leaf absb6yeq.5( xe+osn9qu0 1rtto calculate 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 enters )d4l+wa6z mbhthe Earth’s atmosphere. If its initial temperature was -1w) lh+ d6bmaz425$^{\circ} C$ 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 increasoad (ym.of(6fes 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 hitk wfr ow;r.xm :1vn:7kzy)q o/2rz.tp a soft rubber ball at a wall until they are about to drop due to dehydration an/fm:o 1rzw2 n;k.q)7z.o t:vpxryr kwd 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 gy*d u,nwg-z mp r59(d3rugu7n9:z pkof 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 radiation b8;b tk(p4kycss .* vlat a rate of about 200 W. Estimate how loslbby ;8tvkkp.cs*( 4ng 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”5)u l-scd)3tq:ejvonyj te5 5-nix .3scz g4k left in the 50-gal (185-L) water he) j c jv:lk- 5d.u -3tyit5es4 53gszn)qxcoenater. This suggests 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 9uak;f9oi6dqw5 .mb 3 alfj1o 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.    $^{\circ} C$