What happens to the work done when a jar of orange juice is vigorously+ri dn/77 vibi shaken?

When a hot object warms a cooler object, does tempenj,2h7rtruf 4 rature flow between them? Are the temperatn ,r74ht2 frjuure changes of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will5sjy, fzmm(rfp4/ ac d 4.x.ux heat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possr y.5 ( jz cs/mmfx4,fxpdua.4ible for heat to flow even if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grov( y3q0 v8rzyme )y(mfw but the temperature may drop below freezing a few times in the winte8ymezm vq(fyv03 y()rr, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite )/- np0 y uzsq)v4f :q.rhgoqzojgt 2+large. Explain why this fact makes water particularly good for heatp-v4goq2fsq0jhz)zyr ) /:oq g+. n uting systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket fok-x71gotdv7.5e c s surrounding the canteen is kepo77s cf -. ktox15evgdt moist?

Explain why burns caused by steam on the skin are often more severe than burn :ok 6gjq30hcns causedqj6h0 :3kngo c by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature()qy kjvr tccy55r 1.e drops) when it evaporates, using the concepts of latent heat and inter.cyj (cv t515r kqre)ynal energy.

Will potatoes cook faster if the wckqp ; uf(7ud s0s3+pwsvi b +)mn35fwater is boiling faster?

Does an ordinary electric fant9)i( rq17o h,q3cyc j ldcjeyi cx6)n/f*3e k cool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere g6y4 lbb 7, b/ypox+jd5-dieo, the temperature 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 cove:lq1-j :)v ulg jwxf*yvt4z:t ring themselves with snow. Why would lf*jt wjvg)qyu: 4::xtv1-z lthey do that?

Why is wet sand at the beach cooler to wac j.; d5v+rn;o3dvfl5 ux)az v*b(vz xlk on than dry sand?

If you hear that an object has “high heat content,” does that mea j ouk)79oz 3w-1wsgdmn that its temperature i7 muo 1) dzjws-wokg39s high? Explain.

When hot-air furnaces are used to heat a house, why is it important that there3sss2fjxyf/ikm pht 1er; y9d9 x6d. 2 be a vent for air to return to the furnace? What s2 .ef9k1y/dp;3id6fm9jxh yrts s2 xhappens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in onbxu6zyd9m3 x i7 f62 p*sp*qkde season and pull it up in another season. Which waub q3 27yfm* xpx6z spk9id*6dy should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches or centimetey8r:jv* e u.wprs of loft, the actual thickness of the garment when it is fluffed up. .wyu:e*rvp8 jExplain.

Microprocessor chips have a “heat ncv-n5k7ge1t sink” glued on top that looks like a series of fins. Why is it s kce-7gt1v 5nnhaped like that?

Sea breezes are often encountered on sunny days at the shorlfzw,4 z+5:ulvd 7,5d g15karraodxde of a large body of water. Explain in light of the fact that the tempdzr4x,f dzlal5a5 wv7r+dud5og ,1:kerature 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 i+.* *9 7 ebg blszcmo3tpu+kzjs often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Explas m*ub.*kp7zjezbl o+ t+ 9gc3in.

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 ck,-.h /hcy6hr-twe, 2y y trmth2-yw-6hre,.tmych khyr tc/ ,e shade.

A premature baby in an incubator can 2miabnu jh75.p eqx-06tv /lpbe dangerously cooled even when the air temperature in the incubator is warm. Explaxhpj b2mqi50 -/ t p7.auvlen6in.

Why is the liner of a thermos bottle silvered (Fig. 14–15), anq;b ;db jtzj50d why does it have a vacuum between its twoq5d ;jjbzt 0;b walls?

Imagine you have a wall that is very well insulated dwi-ls*(9 ex t3( iggwu-9krh— it has a very high thermal rshgu wg-t3(ird9w (9*i k-exlesistance, $R_1$ 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 wind)95pe f7ou/cup6 21ciaeia6d. bj h eyows by the following processes: (1) ventilation around edges; (2) through the frap/cfp19ej5 i euyc)6d.aboe i uah762me, 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 reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs morubo i *r1*pe3jqf4 4zle heat than a piece of shiny metal. Yet the wood feels less hot than the metal when yofrz3qb *oi 41ue4*lpju pick it up. Explain.

The Earth cools off at night much more quickly when xccte 1ak er,;*p /j-fl1j-r hthe weather is clear than when cloudy. Why c,txh -lc1p;j er-/kar1j*ef ?

An “emergency blanket” is a thin shiny (metac3;wjljdzo a(x,p;5 wz oy2i,1mu1 b,ehv tt8l coated) plastic foil. Explain how it can help to keep an immobile peu hy3j,d5 i;;(zop1tj c1 2az8,mw,vxtl w beorson warm.

Explain why cities situated by the ocean tend to have less extrempt bja z1l:ka3lc:3 l.e temperatures than inland tk:l3apzc:l lj . 1ab3cities at the same latitude.

  How much heat (in joules) is required to raise the te7 k:6x4v6mstping nb ,mperature of 30.0 kg of water from 15 x7 kvmn6isn, 4p:6 gtb$^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of he*q)ha czkyd, 1at raise 3.0 kg of water that is initially at q, )zy*kcd1ha10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consum4w4i4/ d;ewg9s*o0dkvxn my yes 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 g9 qmil7sm (hd+/sw3 m;iwo* tthe British system of units. One Btu is defined as the heat needed to r; tdsh lwqisg/m*7i+wo(9m 3maise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gcz v: .a5eywpw fg0e 46;ohak8enerate $32,000\,kJ/h$ 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 i atb8dog,*y(v t will take to heat a cup of sou8g(va dy to*b,p (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-unrns-g/ nipjv 8g91 to bring a 1200-kg car tgs-9g/8rpv ujin1n n -o rest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L h jzt1:/7ylog of water. How much heat does it absorb if its temperature ris 7lyg:hzo/ j1tes from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat i2) skgde9s qwx75sw:b s needed to raise 5.1 kg o5swb2xdsqw:es g79)kf 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 xk35bbtn0 e.e xz.ol(pr.z)m fys: l8same temperature rise when they a k. .:lexn) .ml(30frbxs5y ope8zbt zbsorb the same amount of 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 21.6e ccz .729dv vdffviztp3j:(:$^{\circ} C$ 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 245-g block of coppe2v4ai sy eup,1x6vhtz48u 8 miyz6:ihr 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 (m*7 fxamzo ./xgass = $0.4\,kg$) 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 su6ysbzx0 ,n2hubstance 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 toj t1ei-+.tgtu8 cc l:b bring to a boil 0.75 L of water initial 1b.t8+- teijc ugt:clly 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 fpjuijr* z8)drev)a x1 13s ib7rom the following measurements. A 15-g sam81x7zra)d 13ibv*)j upire sjple 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 iron atxdun 9 nm;w d+x4e9zp; p3 /yc.gkde9i 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 hamml h2r. +x8,xcizcg di(er 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 depq;;lp*zjc bc15.dy t fined as the amount of heat needed to raise its tempc c.ptbqy;zp ;5 d1*ljerature 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 initiajq mf): g dqnyktpe2m9.:q/s 3lly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high buiirvjt99wcvy6:gf3) o lding. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its vg9 c3vy f:wtij 6or9)temperature increase?    $C^{\circ}$

  During exercise, a person may gi5 wzl)mt*rcxx yx+lc y a-91:bve off 180 kcal of heat in 30 min by evaporation of water fro*b-lz +ry:9yam5 lwct x)cx1xm 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 container 4)e4 8r) qa4x crvaalab.i5ylof liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of5 vr84ayb )xa r.ael4)aqil4c 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 f t8-:n0ohflmz dr+ b)9gnmr -00 hqkxrrom 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 c/-cm7s7i bhjtontains 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 ove:c2 k-9mset 0pw-i0vplzrj, cr the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water as sweat, how m m 0:rw t2eccv-ps0jzi -pl9k,uch 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 1uq668-yjm(t c 7 jixny00$^{\circ} C$ 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 mercurm h ec:;av80xey 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 traveling4ga8 wl i/wmi2mmpr+ql1jc7) at $250\,m/s$ 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 at 0,fnqgi5.l(rzluahn jot./+$6.4\,m/s$ 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 ih1 zmoihc 9*b+e,rht5nvestigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted complrthc mz bo5,+h1eih *9etely 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 cm is kept at bj)6hx1f5i wgwa2e:5og u, zy460$^{\circ} C$ , 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 con2f)snxon(auyhp 0i* +duction in Example 14–10, assuming that there are strong gusty winds and the +osuan2ypx() fn*0ihexternal temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere q2d)8d-c fwsaa/dt95s ewv5p (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 rvbe3jnzg 7idj 1+e9+ W of heat flows by conduction from the blood capillaries beneath the skidj ev+e3bjnr7g19+zin 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, shifqc /-2ek(/ctl spp/ are a 12-cm-thick brick wall. Because of a number of 100-W lif/ lec k-2p/qcps(it/ ghtbulbs 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 tmp3 wlyf7c l,9btne .3he Sun to 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 anmd8/ti(/ uca 7xlupo +e+iu6o d cross-sectional area are attached end to enuu7o d p(8+ui/ie tco+a6xlm/d (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 whi 30gp5l+f ik 28tc,rejcb4ema ch the whole Earth receives energy from milg4c e r3c 58p+ft2eajb,k0the 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 geiq+d te( u104teiz, fwnerates 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 the difference in temperz0iu (edf+ie1t,q4tw ature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house comwz b7pi;xaje7*/gvg5 zp3jd5 e mainly from a 4.0-in. layer of brick and an 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 arw 77pzbzjxgvpj5 3e ;/ad* i5gea 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 spi) )d wku-i1p jbu:m 8bc0nkj8ace, Fig. 14–20. (a) Show that the rate of heat flow through such a windo)) wk jnpbi -8ucku8:1mdi bj0w 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 itt k58fs l q41sbk:jofx(u+bd8 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 contains9bynx/ qnu. /g,8 fwc3 to35te k9mflo about 0.20 kg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

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

  To get an idea of how m ks ub4l.piv *:m7y;oeuch thermal energy is contained in the world’s oceans, esti:4 obkp7sue;m *l.iv ymate 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.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block o.,4opi49x mx m.acjxryufy 8,f 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 temperature rise measurec,.j94, mypxi a.uyxfo48mrx d as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total pow bukvo g)*3u*her radiated into space by the Sun, assuming it to be a perfect emit)3uukvog * h*bter 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 gen ;,dzlau.xa9fi p2y8nerate $200kcal/h$ 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 ju neriow;k7li r-2 *7my. m9gand falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat gery m9-*77j u. 2melngik wio;rnerated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail de2 ip5k8jth 3ht9w/j of water initially at ek/j dh59jh 83 ittwp220.0$^{\circ} C$. 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 we:diqhflb,cc krq 1-41ars a goose down jacket 3.5 cm thick with total surface areq-f1iqbdc4:h ,l kc1ra $1.2\,m^2$ 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 metabol-rae 0s*r ko 9 u(p t,v4z24crkzxfhp)ism 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 qy5pe6v zm*r, heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the skin is at 3zve*mryq 5, 6p4$^{\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 th; 5bivmf k*liuxr //w4ick (assume conductivity of air) and lvxf4/*i mw/k u;5ib rarea $410\,m^2$ 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 travf7ig6xw;noiy g3 0,ip 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 Problem 58, take into account radiajmjkip*+(gz1h* , :0 lwxk4 gywrh; g(jut8v gtion from the leaf to calculate how gwgp*1wh(rl jz +g8m:,g4ykxvj* 0 kutjhi; (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 the Earth’s atmosphere. If i1i8)mj(k7iid+ c oo gpts initial temp 8c1iioip(k mgo+) 7djerature 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 withirqp 3 fovo: cr +h1st6/*t; qpyz3eyz;n the Earth’s crust increases 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 ajfn4so ml6b a g(3;c4d soft rubber ball at a wall until they are about to drop due to dehyf l3sd bn4(mg ac;o46jdration 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 o:v, kc yqptc eaoq vpr863qe,f; 7(6xequal 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 conduct 4jb ov9g2vto )e66dojion and radiation at a rate of about 2d )ev9go6j 46tovjb2o 00 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 wp0g: so-t,0jx e2ovoiater” left in the 50-gal (185-L) water heater. This suggests t ixsgepot2-0 ov:0 ,ojhat 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 surfap31 h9:;/gfk d dp6u flbnuiq*ce of a 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.    $^{\circ} C$