What happens to the work done when a ja y,dyz5s1ak)ljopne*t(8u1j ap6 q y ,r of orange juice is vigorously shaken?

When a hot object warms a c0c6+4l yj 9a;ry ld6 ppmaak9looler object, does temperature flow between them? Are the tema04pm69 9 +ly;aldacy6j k lrpperature changes of the two objects equal?

(a) If two objects of djn49nlubv2e 7 :(yu0y - fco ale9/rktifferent temperatures are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal enertb yr o y2:7ln9uljv9ae e0k cnu-4/(fgy? (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 belozb2eo xp.q:e xwe w-e5l /9fyl-8exp,w freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced e:w p5 ,b8lyxpz- -w/f2oe .l9qxexeeby watering them in the evening. Explain.

The specific heat of water is quite large. Explain why thg)(x m9lo2h9x k b*lrb*o(dcdis fact makes water particularly good for heating systems (that is, hot-water radiators).l 9g(mbl)h*cbdo 2xor9*x (dk

Why does water in a metal canteen stay cooler if the cloth jacket surro-bire.;nwkq )bdjk0;dg dzx- yp /2+munding the-/yp;d km)z-0xw;e dr 2kbq n.id gjb+ canteen is kept moist?

Explain why burns caused by s2yd6j j/oz)tq team on the skin are often more severe than burns caused by water at 100 62jty /d) jqzo$^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, usvd:l ir(tj/n4ing the concepts of latent heat and in( t vrn/jldi:4ternal energy.

Will potatoes cook faster if the water is ) nks t,p++,nyjm ckf:oh :j7zboiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why c6-il.7 oc5jfeopwj9c4tw; q use it?

Very high in the Earth’s atmosphere, the tempe/qul+px 9 x9ak0 ,ommgrature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering themselvesl.all w d:u+2f with snow. Why would t2w.ld + la:ulfhey do that?

Why is wet sand at the beach cooler to walk on than d8hn9z4 jv3k7( s d cnmuvu2ke6ry sand?

If you hear that an object has “high heanpimbn0.s k os ( cn9p444qpu3t content,” does that mean that its temperature isqok93(pc0pi .4s4 sunnpn 4 mb high? Explain.

When hot-air furnaces are used to heat a house, why is it importantekavnihj+5 h f ;db6x:4h(5zc that there be a vent for air to return to the furnace? What happens if this vent is blocked bye h5jk+fi (4 6h;bnhzxa:dvc5 a bookcase?

Ceiling fans are sometimes reversible, so that ;qdgsn 7/hnwez evz2bn:)6 h9they drive the air down in one season and pull it up in another season. Which way 6nd sv9)bh2q/n;negzh:w z7e should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inc 53qk8 el5:tr)wjb cadhes or centimeters of loft, the actual thickness of the garment when 55):b c3dwt qlarkej 8it is fluffed up. Explain.

Microprocessor chips have a “he4 ubgb7tku)+ain3 3k zat sink” glued on top that looks like a series of fins.uu g7 t4zikk+ 3b)3nba Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a lara/q1xa87hw 1 kfl4 cobge body of water. Explain in light of the fact that the temperature of thec/xfaoh8k b141w7l q a 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 oftudw:e+k.i5r 5j /6rnurlr6y z en cooler than a floor that rests directly on the ground (such a+65 ze5 6r/ikrrrw yu jnd.:uls 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 in tha 14u.bpgzp *vut wc*c3g+rs::cnpe6e :b4 z.gvp1p3cc+ rc uwt sgan*6:uep*shade.

A premature baby in an incubator can be dangerously cooled edn abg09t 2b2a- oukg0zc1z3jven when the air temperature inb2 1g03k9jz2 aabugn0-o cdtz the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14 .vns7koway(, –15), and why does it have.v7,s n o(wkya a vacuum between its two walls?

Imagine you have a wall that is very well l.tijet snl.o+ :8gd*insulated — it has a very high thermal resista*e . sgdjtoi.nt8 l:l+nce, $R_1$ 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) vennu kql;8: jhv.tilation 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, convectionnq;:uhjkl 8v., or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs moream kqy/od*qe4-nrb 5+q6t5ro heat than a piece of shiny metal. Yet the wood feels less hot than the metal when y5+qqn6- b4r oya t 5dqo/mek*rou pick it up. Explain.

The Earth cools off at night much more quickly when t3 hj- p7+xx3 cw0keigshe weather is clear than when3p e 0kj-hs +i3w7xxcg cloudy. Why?

An “emergency blanket” is a thin shiny (metal coa)u2mb41m9ms 9 b7x 131of qqzlsojzdnted) plastic foil. Explain how m 9mz1zdo4s1l1bj 79ub)oqxmf2 sq3 nit can help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme temperatures r h:a3 30+1imc kv+lu+me iflfthan inland cities at th+3mk0 i :f1ulmil3 chvf er++ae same latitude.

  How much heat (in joules) is required to raise thejpuy:gx (ji )( temperature of 30.0 kg of water fromy:j) j(x pgiu( 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water thaah6s./ onv xak:5,c ol0l5bura qpeo5 mg6 24ot is initially at 10./,no 6r cv 6o5l ob: 4ko. amauxqs52a0glphe50 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal aq(egkr+h; xql6m w e-, 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 jlf;n e:j/ pj.:4yxseunits. One Btu is defined as t j:e/ l.efxny;jj ps4:he heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genee o i3+b ndd()pbw+*f+ptk/kvrate $32,000\,kJ/h$ 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 t2n 91ltk -qzfkn y, h+rlz8wx.ake to heat a cup of soup (assume this.zwyr1 -q 9 l8tzf2knlxn+hk , is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakestnlx71s/ cuy6px rr3wo5t+9 h are used to bring a 1200-kg car to rest from a sp1xpsnurht6 5w+o7 yrl3 xc t/9eed of $95\,km/h$ ?    kcal

  An automobile cooling systemelwn zyk(.2 ys6bn)1gck )ff. holds 16 L of water. How much heat does it absorb if its temperature fszwyk2e ))f.g1nn (l bkc.y6 rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat o (rxibtje lu h9c+*(;iirv avrf 0s k95bq7d56f a metal substance if 135 kJ of heat is needed to rai5rv i67ctbk bq r+x5d(r; 9(l0hf va9isij eu*se 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 etyxpco 1kg645v;d e4 axperience the same temperature rise when they absorb the same amount of heat. What is the r; 5 d1y6k4xcapvg4eotatio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rejxa jrl6q( 2oo* fhnw.5b4v;m ads 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 a 2 /zt)q,czso3w 45-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 (massed26nxgq2da. h6gypk)g 1)ty = $0.4\,kg$) 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 heateh,y -*qj tqk4oo.o8 figf 2(mld 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 boydc/2py xb/ :ril 0.75 L of water initiallyyrdb /xycp: /2 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 fir:mi9xnlh x v(1j50m 2pmm6following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminumm:r vljp5m0 inx m6(9m1 hf2xi 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 irsn-a vv3f; 2. ztsw t(ru3jvm.on 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 acja9z cc/tod0z6q sidr, hvl )c8q/:* 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 amount of heat 1 r)ydcc v80 3-fp)*uv -jysyx2olaky needed to raise its kyy1)lp3x8d2rau)-0y* c v o fvc- syjtemperature 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 initian2d6 0w 7kolkjlly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from tonz7 s*i /vyo2he roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sp yono/v72z*is here, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evaporation u9izqj:m6dr7:s 6oe i ofiomris qdj9z7u :6e:6 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 dropped into an insulated counumi1 u:;ms jjr ax)e5 3s79sntainer of liquid nitrogen. How much nitrogen evaporates if it is at i5u3) si1me9u7;mujra nxs j:sts 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 the freezeu ., ,5xtfwkzvvp3m (zr 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 containsncsk s2 -tiu2x c9d1hne**js 7 830 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 bicqu6 +p 4evp gq f*q-jyq(nyh/0yclist consumes 8.0 L of water over the span of four hours. Making the approxi/ +qh jyne-u qyq60qgp(v *fp4mation 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 off.)    kcal

  What mass of steam at 1qvx/7zygp;p v *izi7ow*qy2 600$^{\circ} C$ 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 mercuryv4y* bmhy(lnut, y8t 5 wi8v2r 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 atclh cry.0okjk gsf57bt5a,g-*k5 y8l $250\,m/s$ 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 mo)jbj hg.l2sq5r9 l a;dving 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 no; 59;xt 8v,dt*sibvli t6x s8efrkwt*tes that the 8.2-g lead bullet that ;*tx9xrkf v5wvb s *s;d6,li tiet88twas stopped in a doorframe 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 aluminum rod with a diw: ub0745g uubsz cp8rameter 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 c.uw :afx3kpn/ onduction in Example 14–10, assuming that there are strong gusty winds and the external temperature uawn/k. f3p:xis -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a t*q;9n ounso 0mungsten 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 by conduction from the n :8u(duug)tdblood capillaries beneath the skin to the body’s surfacegd n:u()dt u8u 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- zui*mo +a 8j9qq1wpk.cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air ii+mzqu p*a jok. w198qs 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 blo voqaph,( hh7 rui1(u5ck 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 samv03(6j7ecpjqopcjuzqb 72j (e length and cross-sectional area are attached end to end (Fiec jp7o6( q3v2qp(zujb0 jj7cg. 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 which the whole Earth rh .43vdtkknvzk 1qy1 s4 :t5dbeceives d15v qhs kyvdkz4:13n.kttb4 energy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates2clp*5vw6r hup7:mc2p ok 7bh 95 W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is theph2 pmprlb5v6c* 7c 7k ho:2uw difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a hou*ia)a+ rwozxp- +w 3wkse come mainly from a 4.0-in. layer of brick and o)*3x+p r ai +w-azwwkan 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 se /foi*:haucd: lwh8d ,parated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through sua:*hlwd,:o fu8i/cdh ch a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long should it take 11.0 kg of i7q af/rwz 7qs*ce 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 liquiylt pvxnxx y79il7.+ak/k .h8d 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 containesp*,t p8y9 khmd in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.y8 ,p *hptmsk9)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of wo55lsvj5hpkp4 0 l tl5.fc sx0mod with a mass of 1.05 kg. The block and imbedded bulle5p5k4v 0h.0 fj lp 5mc5xtssllt together absorb all the heat generated. 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,s9 9;8s qnhxoz pw:se into space by the Sun, assuming it to be a perfect em ;nxq:zosehs9s,p9 8w itter 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 person may gene:6zw 6vv g4nd/umblbuo-d)z )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 off the top of a cliff and falls a vertical19he b,.qdlkp height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated 1 eph ,qd.lkb9remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-Lb zzwa/b h7,2bd40a m qv:uw/m insulated pail of water initially at 20b7m2muwbzb/4/,v:h za aq0d w.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 surq jk4i0rtx0k1face arertk0jxi4 1kq0a $1.2\,m^2$ 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 bs(3yw5ph gi jc-1 4b /m*pbwsan average metabolism rate of about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which ./)rfa(ybq-;u yieqaw/ zp)g heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissu.w /r ai)yq ;zaqy-b/peu )f(ge 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 thic8) 2swy21gyo(v6ftlpw :v3bqh da6 bm k (assume conductivity of air) and area ba(vm bw3qf)8:hvw ptyg126d6lo2 ys$410\,m^2$ 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 travelilbz4g:px 3p(t.7 etf dng 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 radiation from thiq6oy3aee6nq8 5372tcq ag a ie leaf to calculate how much water must be transpirye 5eqia7qq36oan6 t8i ga2c3ed (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its init- bly s7 jdbrg7z48 cp91a-uewial temperd-7e9 gs ru71w4b 8ljcb-zyap ature was -125$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s crust increaa7i cmr-tx85ba b*p4j ses 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 of8lb3kn yos;sb2 l t)*o5kv)uw squash (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hbo v t)k2luy wn;k ssobl*)385its 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 wheq*i424i 7nr6 7 dbzkyp;rz1o ytmvw3yn equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a 13 v ktr qnet(.c du1opw408uzperson can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature to drop from 36.6o3ck .z wtq1 4vep(01 dru8unt$^{\circ} C$ 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 h,(yk3-syn e udot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptiedd(ey-uk 3sn,y 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 light 7w3tji91tk )id;xmkvf9u o/a4)fqsl bulb 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.    $^{\circ} C$