What happens to the work done when a jar of orange juice is vigorously sh ak1feqx) rw -5k3/wd3okba+kaken?

When a hot object warms a coo ryax (53e uil7+tbn eh-m1l3vler object, does temperature flow between them? Are the temperature changes ofva+31(5y x bltm7i-urnh eel3 the two objects equal?

(a) If two objects of different temperatures are placed in contact, will hz/ ) ml0hlj, dcr6g f*20wyliheat naturally flow from the object with higher internal energy to the object with lower internal energy? (b) Is it possible for heat to flow even wy r0/m *h6 lifd l2,zglh)cj0if the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperature may drop below fhau1+7po txnk rw+qdgn3l*;)l8 5lwbreezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Expla l8 )1 +htpwrq;nuak 7lg3nx+dl ob5*win.

The specific heat of water is quite large. Explain why this fact makga+y6hk c)8kjn9.out )n0 py aes water particularly goo6uk8jo)+ah0c ngyp. 9a n yt)kd for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sus4xqfy1zvl zym;4 n g)j/e4 b;rrounding the canteen is kept fvny41 z m/qes;bj4)4z xylg;moist?

Explain why burns caused(-q sh;6jpcckw2d z4o by steam on the skin are often more severe than burns causedzswco pj2;kq(dc4 6h- by water at 100 $^{\circ} C$ .

Explain why water cools (itr9tjg32uc b 9w ie,8gts temperature drops) when it evaporates, using the concepts of latent heat andi, b2r ecj9 3t9gu8tgw internal energy.

Will potatoes cook faster if the water ihrli;3 ,qsd3y.extc:1v8h lp s boiling faster?

Does an ordinary electric fan cool the vv2ubfu dw1h 98)7 ofaair? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, ;fjn- c 7l+ncgthe temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Ac ;lqfc0a7wuod. ;f7grctic expeditions have survived by covering themselves with f7wu.g;aqfoc c7l d0;snow. Why would they do that?

Why is wet sand at the beach cooler to walk on than kuwt:,vb+zn 9 dry sand?

If you hear that an object has “high heat content,” ku,2ek :pkjim2n; ;)v boal(g does that mean that its temperature is high? Explain.p;k:e;nl)k, i2bgaoujmv( k2

When hot-air furnaces are used to heat a house, why is it imjk g p t5pmkb ryq(2.9d.t6-wbportant that there be a vent for air to retur.pt (m-gtrbb2.kwy9 5j6q kdp n to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that th p e:7yn bxxohqli- il1*f*10cey drive the air down in one season and pull it up in another season. Which p* i- c7*hof1bl:q eiynx1l0 xway should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inchebsm2r9se5t( as or centimeters of loft, the actual thickness of the gare sm592a (bstrment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks like a sericsy; pz3q :8cjgs d/s-+3xhkwes of dqs3gph:k y +zs8/s-x3 c;w jcfins. Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large bl),0z xe6ep,mm5r .to smkq,yody of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of the,xs eo) q, 6 me0r.pzym5mt,lk nearby water.

The floor of a house on a foundation under which the am fahf2tr.s/, o13fvrir can flow is often cooler than a floor thatff13ts/hr mvf2r.ao , rests directly on the ground (such as 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 ;-;k6cwm/rk9 gc(vebs d u)mjare always taken with the thermometer in the shkm6j;mvw)/(u9c ;esbg- kr cdade.

A premature baby in an incubator can bewd t *dbt*e71e2, qhev dangerously cooled even when the air temperature in the incubator isd*2w7*hdee vt,tqb1 e warm. Explain.

Why is the liner of a thermos bottle sx 1 dtqcd-s;0nilvered (Fig. 14–15), and why does it have xc; 01qstnd-d a vacuum between its two walls?

Imagine you have a wall that is very well insulated — it has a very high therirp ( n.mnlm+d2yv46 emal rn4mn+(l dve r i.y2p6mesistance, $R_1$ 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 followin c*c 4asq3,8l4d9qblspfpx 6yg processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; p6c3 cf yls*,bpq als4dx984qand (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 more heat th/b1w tr xf4t-)g/n iy yhtl.y5an a piece of shiny metal. Yet the wood feels less hot than thlrf 4y5/iwy1 tgnx/ h)tb .y-te metal when you pick it up. Explain.

The Earth cools off at91zu:fxj hr y: night much more quickly when the weather is clear than when cloudy. Whyh:r1fj9z:x uy ?

An “emergency blanket” is a thin shiny (metal coated) plastic f 1 lw9s3glo waq-*hv(hoil. Explain how it can help to keep an immobile person wago3-v(wwlq h al* s9h1rm.

Explain why cities situated by the oc+m6 zh1khrv6, f yvt, ju6e e e2w,vttm0dgd97ean tend to have less extreme temperatures than inland cities ae61vmuev +,7jd9yehr6k 6dg,ttfv2h m t0w, zt the same latitude.

  How much heat (in joules) is rehqh(4;)cdaa*p afk3we sh -0hquired to raise the temperature of 30.0 kg of wate*c a we hqh4)khsad(0p;-hf a3r from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is initia 2k(u:oniy3zw ;m +nuslly at 10.0 +mw:ny(uui;n2k s3zo$^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal *qn g t0 vw6f;ciomjt.u 1xx1b,9)8ho8jg tjoa 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) 8: 2tr7psbnk- 3adtez is a unit of heat in the British system of units. One Btu is defined as the heak8 7n dze3t tpsra:b2-t needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can g yog 1i7j -wxxfc2e41zenerate $32,000\,kJ/h$ 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 tpte m +jn n3lp89m3l3cake to heat a cup 3 n98 mj3t+lpnpeml 3cof soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated tmdj7q0,a ei)when the brakes are used to bring a 1200-kg car to rest )m d 0tiae7,qjfrom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much m.loer,muk /x 9 n.tc.heat does it absorb if its tempetm/.rcno x..u9ek,l mrature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJt 6nhv4kj 23kf of heat is needed to raise 5.1 kg of the metal fromv6k2fnkj t3h 4 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and y/v o4q8u+ c8 v*irfx gcz58tcwater experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their m/ +v* ct48cic8gxqr uoy5vz 8fasses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomet31lc9y 4gy :.uqq7 xj4cpwvlyer 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 a 245-g bl*udv.w n-enwji cp.0.ock 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 xt .)o/zn eyel6sh9 5ppm07h:da4qo g(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 hz6jrqs2t8 y y16md36(lv6-hwc 2hhindhac4reated 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 0.75u.i:gp7sr n,a-49ob8 dbjho f L of water initially at 8osg8 .pjh ub,n4-:obraifd 79.0$^{\circ}C$? 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 contene)ix.7 ozk-y1(d9d tvpyucr*t of 75 g of candy from the following measurements. A 15-g sample of the candy is allowed to dry (id.pktrx edyyv)oc7z9 1* -ubefore 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 atl5 d643jf aksv 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 scijg1z v x(dnvz8f *pm f9)(8a 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 tznp zohw /y:.-a(i7gcn0*bm lhe amount of heat needed to raisehway/ nzp(gb:cim* 0-on.lz7 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 dy4xto4n;cixew9w3 5, zyw +dmelt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is drd m(/juz* )1 (geofsgwopped from the roof of a 45-m-high building. If 65% of the thermal energy pwg1(jo*fzs )em u( d/groduced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 184q8wlu 4i11zd xqw -gl0 kcal of heat in 30 min by evaporation of water from the sql8w4z1xig 4dq u -l1wkin. 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 2nvu8c4przpz:v7 x:v of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent4:2rn:p zcx8vp uv7 zv 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 take5yedt qiw3du 9h4h :r8n 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 8;/ lrg v1v8kll30 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 ov8ty cls;04 uouer 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 aboutuo8s;uc4 0 ylt 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 100k8 txnc *,;wrq$^{\circ} C$ 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 i7to smb)myy 1l3z 1sir)o050r1 uqfijs $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(sy * 4kgp74 lzir(3kyefyb -(l1qyds 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 +i4u 5 zwunns)at $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic investigator notes that the 8.2-g lead bullet c 6lpggtq9k 4v07ge) kthat cgk70 g4g9ev kpt 6)qlwas 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 diamlm 9 a6yit5kdjd( n4f.eter 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 con0p9hgczl h7 g9+cjub 9s9t.lv duction in Example 14–10, assuming that there are strong gusty winds and the extes9lg9 b .cl9z gpuhc07th+9j vrnal temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten spheretnzt l+6el 3rw, ffe yxg5nas qvu6w+,8s5(9e (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 ( 47u m8qlqb 6bxvay,xconduction from the blood capillaries beneath the skin to the body’s surface area of m6 b4l7 y(q8xqbuav,x$1.5\,m^2$ 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-w;q*8q61xfq cu xq -h oayg48ncm-thick brick wall. Because of a number of ahfo;c4ny- 1ug8q*6 wx qqq8x100-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 tormxn4.kxs f64 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 r jvv )mx;(dvdq )i7e/kod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The c( meikv)v q)xd7;dv j/opper 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 fy ru0zp,z091,glij k5s+m wpch the whole Earth receives e,glyipzk9 , z1+sf0wup 5m0jr nergy 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 gene s*q.ttum 7kfb(tue8,rates 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 temperature between the inner and outer surfaceubq* ( ,kt8tf t7mus.es of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from auq ( 1rp-q-i cb6h0xg dqfw79c 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 cp9q 6 fq-q(bwurcg d-1hi0x7 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 pan*/6f 3kupmkwv es of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through s/f*uvm kkpw63uch 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 itu3r8 wpw-bq 8n 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 abou1 tt6 n pd2w ;*nmrskoba1w0g,/x15ahr: urdkt 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 much thermal e kswziic r2t0 0+gj4d 1;1yanznergy is contained 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. (Approxima1nrd4;cis 0z1z w k2gj+yita0te the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing io y5q+-tj7y3tv owy4xt 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 hasqvyt w ox73y-5+ojty4 been reached, the system has a temperature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming it tbq6338eo. qeovj y 7uao be a perfect emittjq q8oeeau7 y3o.b36 ver 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 maip7m g- w7sgf,ebrk s 8e5;t(ay 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 of a cliff and falls a vertmggjl671d7y sical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in gm6sd17 gj7 lythe rock.    $C^{\circ} $

  A 2.3-kg lead ball ir 3(f5)mvdeq ls*qs*h s dropped into a 2.5-L insulated pail of water initially at 2l)d 3qfses *vh5q *m(r0.0$^{\circ} C$. 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 thic .ivd 2sowoa-w9n2mj9k with total surface areaw2o2v a-9 sj.wmion 9d $1.2\,m^2$ 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 metabolism rate of 2/8m9yo)zi+pyld w b0evtna 3about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which heat can be conducted from the inter4ddgp +gke 4z;ior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, thaed4+pkg4 gd;zt 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-insulephqr4gej /m,4o x w 2ko( omy,3k/j7tated walls 17.5 cm thick (assume conductivity of air) and are72t,4wg3 eemhjr kx/kqoy,j oo/ m (4pa $410\,m^2$ 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 tx3xy p/h o)12aoemd )xraveling 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) e2s5k(to.js nqu j;k;2sa e 4nin Problem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature ofjnue es4os52 st.anq;(2 kj k; 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. If its ini03q / vsq772mz( l*woc fo+xbcpiraztknq 0.,tial temperature wa2(misz0o/kfc vqz,lxrtq03 cqn wba 7+o7 p. *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 withixgg9:xu nt0 g4smbg :. skm3;bn 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 a soft rubber ball a(7+g zw ihs q.vfeqo0 s9s/yt-yv 2i*jt a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at asi.iz ysoy*09 f- gjh2 eq7+vvs/ (tqw 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 equalb an6:kvx6fv .rrjf9 velt:e)+u/a *m masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a pec sh 4:6x+ybozyl6 j5urson can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperlxczo6s+h yu5 6 :bjy4ature to drop from 36.6$^{\circ} C$ to 35.6$^{\circ} C$ if metabolism were nearly to stop. Assume a mass of 70 kg. (See Table 14–1.)    s

  After a hot shower and dishwashing, there is “no hot water” leftz n;,aqoun.r6 in the 50-gal (185-L) water heatr.azn;,ou q6ner. This suggests that the tank has emptied and refilled with water at roughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass su)u nxwq7 x3vpt(co+e0* eqg s9(gbx5b rface 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.    $^{\circ} C$