What happens to the work done when a jar of orange juice is vigorously sh1hcs+gf v/k9kgi pyjs)y673 h aken?

When a hot object warms a cooler objectx ovz/x5-v q;u, does temperature flow between them? Are the temperature changes of the twv 5/;o-uzqxxv o objects equal?

(a) If two objects of different temperr9g5;hzm.f+ njow) npo.hlr5 atures are placed in contact, will heat naturally flow from the object with higher internal energy to the.+pwm;hhr 9.ozgf o5nrnl)5 j 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 tb8h60tmllg 3 hemperature may drop below freezing a few times in the winter, the destruction omb0l 3hgtl6h8 f sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large;t(sbx2 ro+jnra)m- r. Explain why this fact makes water particul mr2rrosa +(tnx;bj-)arly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the clothh,0 ikvn,t/myf+a395o 4pd bdvogm ,m jacket surrounding the canteen i m+vf 4 d,/gnk9y,bto, o5m 0ivpamdh3s kept moist?

Explain why burns cau p 2qk,mnpp6,/icpf(06xlsq esed by steam on the skin are often more severe than burns causedlpfqi e,/psnx 0cp2mk6p,(6 q by water at 100 $^{\circ} C$ .

Explain why water cools (its tempezvg+bybn 0w5x)sx8mvx1.p jq5 9*+u7 ojamewrature drops) when it evaporates, using the concepts of latent heat and internal e 5z wuw0bx. 1v++b8os)j7gny 9jv xq5mmapxe *nergy.

Will potatoes cook faste;tg8xc61 ixzvbrr / 8cr if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why us)pi65l p9ef (hx3kjege it?

Very high in the Earth’s atmospmb u4-v t5y/muix *v)ihere, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic exp3 sjkifxl,5yif- a 7e3editions have survived by covering themselves withs 5-a3exf,jfi3iyl k7 snow. Why would they do that?

Why is wet sand at the beach cooler to walk on vxci/qnv935s than dry sand?

If you hear that an object has “high heat content,”b7v;4.c mipsvi +t gh+ does that mean that its temperature is high? Explaics+hi4t vvb;. 7ip mg+n.

When hot-air furnaces are used to heat a house, why is it important that )tg 6y:el4n sbrj6bj vxoa(ah7 (3u9lthere be a vent for air to return to the furnace? What happens if this vent is blocnho lbur vy gja(64t7693j:()bsexa lked by a bookcase?

Ceiling fans are sometimes reversible,pq*gk-2fu-mr zg0;s s so that they drive the air down in one season and pull it up z-2k0su pq* g fgrs;-min another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many incc 7pk262:yra dre)vtw hes or centimeters of loft, the actual thickness of the garment when it ctr26ad y2wp7rv ke):is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top tlk(lz -rm:: brhat looks like a series of finsl lkr (:mr:b-z. Why is it shaped like that?

Sea breezes are often enco4 .4 wt3ppbzyuuntered 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 more rapidly than tbzp4 wy4. up3that of the nearby water.

The floor of a house on a foundation under whw r.i g66mt1 cg1nmz:uich the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab found:g6 1i m6mzutrcw g1n.ation). Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperature reading icraw ;j078pds are always taken with the thermometer in the sha8wpc rai d0j;7de.

A premature baby in an incubator can be dangerously cooled even when thlsuz8 wge 51,1uqw eu-ar:+r be air temperature ue qw sw+egbu1 ,ar1-8: lzr5uin the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig.pdgwgnni5 .75z4 t*qk 14–15), and why does it have a vacuum between its 5nz54kqwp 7. gdgitn*two walls?

Imagine you have a wall that is very well insulated — dzc x b6 n86nnp39mf)qit has a very high thermal resistance,f6dncp86 xnb n) m93zq $R_1$ 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: (1) venti dgt-oa7 q*kvswytu/7f w2v8e7 pf20yll 90shlation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reductf/80svls7t9yg w 0*oaheq u7f- lvdy w72p2ke which of these heat losses? Explain in detail.

A piece of wood lying )i*p; md pkme.in the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot thkpd.; )i* emmpan the metal when you pick it up. Explain.

The Earth cools off at night much w1ashchqg3d .72 ,x) /llyw g6f ujj;fmore quickly when the weather is clear than when cloudy. Why)hq/d y.f1w j,; fwa2gjxl gslh 6c73u?

An “emergency blanket” is a thin6pl px o813z- hwcl7 qwp3pz4vsc*e0a shiny (metal coated) plastic foil. Explain how it can help to keep an immobile person wa8z4l3h6x cop wa 7ezc svp*w1qpl03-prm.

Explain why cities situated by the ocean tend to have less extreme teolec. * 4*iamg ej84 n84cqrtemperatures than inland cities at the same latitude*8 4*qeacno4 .jrm8e 4glitce.

  How much heat (in joules) is required to rai*juj:qg .g7aiq6y.9okxj6 e lse the temperature of 30.0 kg of water frogqj. o:giyul7a9 e6j*x6j qk .m 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raissc w1xr8 so. q3x3nfh-e 3.0 kg of water that is initially at h 13qx8oswcs3 .-nxfr10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 j 2om.;6qz pgzjjdk +9bpxw) *bl)ow; 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 c/gc 3sj0uw0t9zy ,.clno9qf vxctcozt,:0, a unit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lb t,0o 9/vf jyosct cz0gl ,z.:qc9x twn0,ucc3of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generat6l v ebc1g+7f4 m ln)ojk7e3(rsmfyl 9e $32,000\,kJ/h$ 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 take to3gw9ma5 1xd,adptc mj+bl4 n3 heat a cup of soup (assume this is 2 n3m4d3wtxdpj1 ga+5lm ba,c950 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 120.m acxe9c yp9xr4o/ 8j0-kg car to rest a m eoxc4y.9r/8 xpj9cfrom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. +hy 3dfniz,v8g3s 5 imHow much heat does it absorb if its temperature rises from 2 +iy3h5 f ingv38zm,ds0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is needed to rtkm)cjxks37- d 8dpgoou+: -qaise 5.1 kg of the metal from 18.jok7p o3-)kddt+ cu -sm q:gx80$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experi; (nr5m -ac24 fgrjkevence the same temperature rise when they absorb the same amount of heat. What is the ratio of their mas24gfjrv- an k (m5c;reses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer r:d p ;9-/mzoklzjrfe0eads 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 equre/4i.-j1-i ei-hzkeo1un f filibrium temperature when a 245-g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe hjs;etae hzd)7/ww.3 (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 substance is heated to t/0:wbnb t:j8 v)hy x1.hckgb330$^{\circ} C$ 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 coffeepo dtyp(p,jw4 z;t to bring to a boil 0.75 L of water initially pd( j;t,zy p4wat 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 tp /uxk 90urwfm;x 6rv.he following measurements. A 15-gv0 x/9ru;uf .wpm kr6x 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 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 ir 8x4 ftv/zifn:l(ha m6on 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 nkk0+ hn7i0,7qqmz8dumx ysep f* **espeed 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 theqsthe) -jay28 amount of heat needed to raj-at8s e) 2yqhise 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 o0z(t cbmu f2(kg of silver 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 building. If1u ,kwu -doj8j9axn9o 65% of the thermal energy produced when it hits the grono-1d , 8w jaoxuu99jkund is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 1a2vy a-hz6xtx 39 )hcl80 kcal of heat in 30 min by evaporation of wa 9hl3 acyt2 -h)6axxzvter 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 dropped into an insulated,c4/ g 3bjtnxl container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporizatio3j/nctblg, 4x n 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 takenxv8jr(ie 56vl from 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 mass 230 kg contains 830 kg of water at 18 fyf u.9mb6tp:$^{\circ} C$. 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 ovmj ho0bibr 2+,er 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 energy consumed does go to heat, so our jrobm0b,hi + 2approximation is not far off.)    kcal

  What mass of steam at 10zn)kx yly:k5q: 7tfu03 tm d;e0$^{\circ} C$ 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 mercury iifg vubp7sov6wv+ 12+uw :lc,vi2vm 7s $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 aj)1a (l-tb4 e j,euczz2nwx5 qt $250\,m/s$ 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 a 2o 6hvsstf8l1qpge* ; zov;;yt $6.4\,m/s$ 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 vi5mx4e l4f ek,fmhm 4d56w q)investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fired at room temperatu)vmf hw5q, imml46k5edx4e f4re (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 u7eb (ud-uiz7 a;yw6k 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(,1dohf10 t ,vrj), 67rj e bwnyiufhj flow by conduction in Example 14–10, assuming that there are strong gusty winds a ejyr170n bvru(),, jf6, w 1ofihdhtjnd the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiatex)hy 9 9vq4cted 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. Supqb1i7h ,rzz7ol 5ke3epose 200 W of heat flows by conduction from the blood capillaries beneath the skin to the body’s surface area of 5 7o 7zqei 3ezhbrkl1,$1.5\,m^2$ 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 sidb(xgbskh8 5p +4yw2y c1mls) ce, share a 12-cm-thick brick wall. Because of a numbyscwbgc+ l5s ph bk4x82(my1)er 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+ h;ih1movt)ipnk: uq2lf ,/q4zd 6ng 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 l9-lp06 cn3dveu3 vuslhka 9r0dd s, *zength and cross-sectional area arev0- 6k3zd h9edl csd*rul,pa0 n39suv attached end to end (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 ra58f ueeqicu.w .rnh/ 90 eh(mcte at which the whole Earth receives energy from the er5.h(unwhf8u 0ci /m9qee c.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 generat: r7hweg9ajwnl: 1lwxdu w/, 2es 95 W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cwe1rwjda w/,:l un9 2:7xghlwm 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 a house come mainly from a 4.0-i71j.elsj( ak -xxa31 u3bthkwn. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat lowa.j( u 1ja1 -kht33esbkl 7xxss 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 gla2v6mybp 8o. .tw sbfr(ss separated by an air space, Fig. 14–20. (a) Show that the rate of op8m.. b vb(6fw2rtysheat 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 lof6*lzq n2e4e7ba(hxn0.o wuxx;.h lj7c zv w 7ng 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 liquidf*ah bj,d:1i m 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 oceq i *a5ct(-wdob(+ *hglzeg r/ans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (ga*hc5(z- dgwrbe/ ti +ql* o(Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by fie. md22wsn0pt ring 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 reached, the system has a temperatepmtwns.2 2d 0ure rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into m v,bkj56 0nrm):vorj space by the Sun, assuming it to be a perfect emittv6 : )vkj0njrbm, o5mrer 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 pe5-/j/ n9lru eenw )tk. s:seherson 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 j)zg v*p,,6 tgh+si iqof a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature ,h 6tqg+*zjipgs)v i,rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-/.vcw) ri bdzx+d4.e c:d kwp03bjps+ L insulated pail of water initially at 2pw. ++r.edvj 3d/cpzbb isd0wx: 4k)c0.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick with total surfac snyodg3)(p+ ,*zhp hxe area+ps3dznh) , (ogyphx* $1.2\,m^2$ 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 meta8i;wj.2m pplx :zz9 ffbolism 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 conduchh- y.bxpeg1.3cpoy( , c+b ewted from the interior of the body to the surface. Assume that the thickness of y+ep gx1-ceybpbc,.h. h 3wo(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 conductivity of air) and 1d; pjek4,mmu p 1jmudm; 4,ekarea $410\,m^2$ 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 travelinlfpm6 tm2*v f.g 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, take into account radiati+g.ifq3 zf1yx1 q. 1piz9wqxg on from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain.. 31fiqgxqzi g1p9fz w1yq+x a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmos*in, anb ,cm3hphere. If its initial temperamnc, i3n *a,bhture 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 1.0 x7pvvfn f8 c)2C$^{\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 softq ,u k- osd*)piuta-4t rubber ball at a wall until they are about to drop duea-s utki)tdup -*qo, 4 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 e*h *rnwa49a,/hpu lf2tb+ byi p+y9fmasses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose hep (x.kohr gqkrgr+h,c3/t. *z at by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop frorhhxkq,+tr g(*.kpcgrz / .3 om 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, thyd)g 5im8(izc ere is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the t z(m)8ydi5cgi ank 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 60-W lightbulb is 65l-ahb t6qb ad5(h.u 0d$^{\circ} C$ 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.    $^{\circ} C$