What happens to the work done when a jar of orange juice is vigoroj4n qp9gos. c)doq*s5 usly shaken?

When a hot object warms a cooler object, does temperature flow between them? wym ,nhz0.u.oAre the temperature changes of the two objects equal?yo0 .,nu wzhm.

(a) If two objects of different temperatures are placed in cddh(hxi5xm 4/ dz,up3 ontact, will heat naturally flow from the object with higher internal energy to the object wid(xh5 d ,p iumzd/h34xth 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 drogr kvthghi+ 1-vsb0 q7;3kwt7p below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Evb7gr-s1;+hhktg7w t 0k vqi3 xplain.

The specific heat of water is quite large. Explain why this fact makes water parg78 vz9y5h) jxask1brticularly good for heating sy5a9k br 7hgx18jyv sz)stems (that is, hot-water radiators).

Why does water in a metal c6xz lg4.b )gy uoq gyb)k);6ttanteen stay cooler if the cloth jacket surrounding the canteen is kep6bz b) kg y4t6x.qgygu))to;lt moist?

Explain why burns caused by steam on the skin are ofih x cf ;fow96gd80(ly9ovj /zten more severe than burns caused by wojz9;xovw 9c8 d(yl6fgi f0h/ater at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using the j)h30t5ieb ;vkosg8b( coo1z concepts of latent heat anjviz3 0 ghooob e;c5s(k 81b)td internal energy.

Will potatoes cook faster if the water is boilio8aqo90dd ** c3bqybpng faster?

Does an ordinary electric fan cool the air? 3lxs3;e (qezg Why or why not? If not, why use it?

Very high in the Earth’s atmospherec o sbrfr lt)ueo7.+nj3mm7 +467br iv, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions h5)oud qj( l b0w(tz;-7hoxj oiave survived by covering themselves with snow. Why wt0o7 bj)(q-j(5 ;ozilxd houwould they do that?

Why is wet sand at the beach cooler to walk on than dry mq951 j0qtpw 5ax5zsmsand?

If you hear that an objectzxbcy8: 0yd ac rg3 .mh12jt kzpy5wk349cb/b has “high heat content,” does that mean that its temperatur3cw50 :y1bjtz3b28c49yymdkz.gr kaxbp/c h e is high? Explain.

When hot-air furnaces are used to heat a house, why is it imp 1 4jlamgj m2z:b3sn9rortant that there be1jgl9mm 42rjsbn :z3a a vent for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down lfcv:i0f)a0 uin one season and pull it up in another season. Which way shv)0 fu0afl :ciould you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches or ce zn0ldf8 -*e7gdxp):qm7 yiie ntimeters of loft, the actual thickness of the 7 8li* )n0f qpdgedi7y:zmx-egarment when it is fluffed up. Explain.

Microprocessor chips have a “heat sinka5 69p4)tz4rhc rm2l0eyzvpk” glued on top that looks like a series of fins. Why i6 k4)rzrpza9e42t5mvyc 0h lps it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large body y:h wl)ezown7 9)-zdw of water. Explain in light of the fact thatwzohw-le9zw) )nyd 7 : 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 coolbg bwhy(c9 f3x5( c:w,/bd; djex r-wzer than a floor that rests directly on the ground (such as a d;cc 3h/g re fzx bb dwj(y-b5x(ww,9: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 withn)r/ f e+azfl kj8kx;o7bwb77h( 7d2nxtker 1 the thermometer in th7fx1nhw(2o/ dn jbf zakl7er 87br)tek7x+;ke shade.

A premature baby in an incubator can be dangerously cooled eve9 n /,1,rdx3ij mxiitjn when the air tempem,,dn i9xji / itj3r1xrature in the incubator is warm. Explain.

Why is the liner of a thermos bottle silver;j if(tzd( v; jxy)jr)b9d o.yed (Fig. 14–15), and why does it have a vacuum br)d z j.vi (dyx jbf;t);ojy9(etween its two walls?

Imagine you have a wall that is very5 bg3zhf5o b 3usf2.op(hc 6ez well insulated — it has a very high thermal resz3ogh2buo bf 5p3h fc( z5.es6istance, $R_1$ 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 following processes:mk gyp.-zf ;1nm6k1xkkwe* + p (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 curkp6kekfg;z m.p1xmk* n-+w1ytains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs moru ns kh-y7h4v, :*kuzgwpd .2ve heat than a piece of shiny metal. Yet the wood feels less hot than tgu,hdkp w4vk2s-*:z 7u .yvnhhe metal when you pick it up. Explain.

The Earth cools off at night much moreppt 6zo0q -2r3gwg/kh quickly when the weather is clear than when 02-6k /r qpozpgw th3gcloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil;u -bag94yl ai. Explain how it can help to keep an immobile persaibu;-gy a49l on warm.

Explain why cities situated by thekq3 h gfr*v14ihl e/ m3 n29lxg8wmni. ocean tend to have less extreme temperatures than inland ci393/h. glnvm8i im4kfr2 qwn*e lgh1xties at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0 kgvp5wutg2 )s )b of water frovg wu25))pt sbm 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat rais5epdzwx4c y3ca9yy c9a 35) rne 3.0 kg of water that is initially at 1 9z5c pwy453)aard ey c9nc3yx0.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active persont:/c j nb pn-i:pc.yqw8(tgo ()p z-ny consumes about 2500 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of heat in the British system of dwhg i 9c,*ce6units. One Btu is defined as the heat needed to raise 1 lb of water by 1g hdw9* ,c6ice F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate7c08szm /aidljf 8; k3k-pvbl $32,000\,kJ/h$ 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 ltp u8xosh q91-ong it will take to hea8uot9hx sq-p1t a cup of 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 to br9 le* ulk (zj)v/w au.9efn2sfing a 1200-kg car to rest fro2u ) 9*9le/ fe. nlksvzjf(awum a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water+7;7cd veyfgl. How much heat does it absorb if its temp gef;l7ycv7+d erature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a ld3fw+*r0k b: aw -covmetal substance if 135 kJ of heat is needed to raw-vfk *: o30lrbc+wadise 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 tempepesgtq72ew*d1 00q.n dn *bjhrature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: See **.e2jd hdqt wng010qpne s7bTable 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomev69icdn ad b ::ohq *vj:c, 243givvlxter 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 when 8c* t)b0f*mhz 0 wglfia 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 my 5h5)sb rhy h2i d,sk.og0gga(e9o:= $0.4\,kg$) 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 heatedz cy5f3;u)ve,4nbkcjh7:an2 zffj- g 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 +ygkd v o1u6bsib3m;9L of water initial1udm + 3bk9gyiv;o sb6ly 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 from the followq0ja 9.tha9-vi k+jching measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperajvia .0c9t9h- jq+ ahkture of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron at(v)bt (h*k ,pm*:myfn .kqhnf 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 ham5v3ju/8uj7tnfkh . wx h/e7xemer 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 td33d -i:vqc zk0vql +amount of heat needed to raise itl03-ctdq k ivv3zqd:+ s 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 16.5++djkuc sieg;+n. :ek3aih 0q 0 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is droppedy( ptk g4uoz.8 from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the groundkyzu(t4 8.ogp 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 by evaporaly0 a/n;+0n aj.wd g.xx m1u+vz9qthmtion of water from the skin. How much wnmjn;+x v10zt .ad9qul.+xa hg0/ymwater 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 dropped into an insh5e4m*+s, hgilaa j z/ulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 h5je*ahi4 mgz as/ l,+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 gcf;9 yc8/o+pnyc t )y$^{\circ} C$ 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 co y*mv-e1ws.sontains 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 tnnwno6f3k gnzy23 5ib7-0 arvhe span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so onaw if6n5zv3 gb-03o kr2ny7n ur approximation is not far off.)    kcal

  What mass of steam at*1u-xa o9mqk x 100$^{\circ} C$ 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 me*+/ nhxek /dot ;uak5nrcury 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 a5;v3 2hpl d4t bdb6otet $250\,m/s$ 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 atc/d0wu,c+ o3z na lhu8 $6.4\,m/s$ 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 invesw1u0lvf nrh,m en;rtg7 e3j1)tigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparen g,13wmule ehj;nf t10)vr7rntly 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 diameter of 2.0 vllc,ai-wpl4:r0 vwcu1y2pb5* r i/ vcm 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 conduct;1ghql5bclp2c1u k5e ion in Example 14–10, assuming that there are strong gusty winds and the external peqc5k51 hclg;2l1ub temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a 6qp .4z5fsi b xb/gnf*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 Wc*t2r(xpqv5i y6w8 wi of heat flows by conduction from the blood capillaries beneath the skin toy8*(6i qv rxw2 wi5ctp 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 cub: d..htz9;po9 edl fvie 4.0 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the a.ht99o vf. dz ;eilp:dir 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 r7zd/*(dvlcd hm2r2 k melt a block of ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sectional ar-6 6+se;w)jjfhl zka9ilsu u4ea are attached end to end (Fig. 19+h ul 66jkas)ie; jfluz4-ws4–18). 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, estio2m / ;ql jdsaqo*j7gqv4p:8emate the rate at which the whole Earth receives energy from the gjpqm ao:728 odve/4 j;sql*qSun.    $ \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 dissipa6:xl lkg. r9+vo.bw trl9g 7lbted through a glass bulb that has a rlx69g. rl.lob +:7 9wgvtblkr adius 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 ovvrq4qoi :+) og6wk3. q1s ixdf the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation.g:i+ov1ok4q)w6vd sxqi3 qr , 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 hasb(:0wp )hk cnw two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rkw (pcn:h0 w)bate 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 sh6ycnr7) zzndipzf20 +ould 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 liz 2bvt4fn2 9fk71acq,8mqy qwquid 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 ocean-- aicsyqns 8b75yby/ s, estimate thy n--qi8/ 5ssybbyca7e 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 this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a2 lgc .n 2 v01ii9spb*rqcam3d 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 reached, the system has a teq0rlvb 2sc39di2p 1 man.c*i gmperature 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 thep.kvdzx /1o6sq 3. ulg(mmmp 4 Sun, assuming it to be a perfeu 4mvmzog p.3 xqsd.1/m6(lkpct emitter 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 activity, a 70-kg perylt: vp)01nl,g , cl ocl5wlb*son 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 r s; 1a4uqzc1exgk8bh 9olls off 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 gene8cq;91 bgahukez1 sx4 rated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water in;d s1 :uo cdis6g:+r1*lm r lrmrk-)uhitially at 20.0- +dc 6 o1di*rk:;su1rr gulhsm :l)rm$^{\circ} C$. 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-xog4xw11qh z a goose down jacket 3.5 cm thick with total surface areaxho-z q14 gxw1 $1.2\,m^2$ 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 metaboli/;-xy8ug(m ktyvz 4 gksm 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 condxu7 eejwu5/ 18omf0eiucted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is x/15e ju7wme8eiou 0fat 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 (a, qfrmbl t3:e8 w 35k+e9 gk.qu0dxvjyssume conductivity of air) and a3 +qqe w9jlte3um bk.0d 5k,gvrxf8y:rea $410\,m^2$ 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 travel 7q+f2c2 9ym,xo+y*ba*ayzha dye14yg )hpt bing 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 5cc,tv;lr*y s Problem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the lea*5;t rcycvl,sf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters t 3+yqgqql begi hga)n.)5y -k2he Earth’s atmosphere. If its initial temperature wa 2lyheiq+3bkyg) gg 5qq. )an-s -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 increa,j zed(xe +x(t2o5sg eses 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 ath7+ h j(aqyugir3rj+p-n*2e c a wall until they are abou hcrhp*g - 7ier+qjj32ny(a+ ut 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 resultx-7sfc;bhj2 i2fgu m4 88g rhb 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 radiation at a ; i7vfvul jyk;p( ,bt0rate of about y 0( tv,l;uvbkipjf ;7200 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 wxeik1 /olliprclvwhx+ 2w 5w :5k /g)8ater” left in the 50-gal (185-L) water heater. This suggests tl kxwxi5/+hi1e5)wlorlgwv 8 c2:kp/hat 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 auf+k6i8m6b wa 2bmqdxa ncv78d0/- qp 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.    $^{\circ} C$