What happens to the work done when a jar of orange juice is6( i wt-j)keyw vigorously shaken?

When a hot object warms a cooler object; s ms2u7 2tylco f.,i2eevgt:, does temperature flow between them? Are the temperature changes of the two objecttv:.u2s,ctsig;m7leoeyf2 2 s equal?

(a) If two objects of different temperatures are placxzt)9*ot)zd9qu/yjf ) sm u9 ped in contact, will heat naturalt jutd9 )my)x9) fp/uqz*o9szly flow from the object with higher internal energy to the 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 temperature mqaz1j 2/d4v jrd8j8dtay drop below freezing a few times in the winter, the destruc avd24818 /jjt qdjdzrtion of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes wake f f-g5, ;ztzir2/sdter particularly good for heating systems (that is, hot-water radiato-,;re i2zfdkts5/ g fzrs).

Why does water in a ))b4a3ewbcnametal canteen stay cooler if the cloth jacket surrounding the )c3beaw na)4b canteen is kept moist?

Explain why burns caused by steam on the skin are oft ot48pw /,b p:gbpr5mren more severe than burns caused by water at 100p,tpo5 gr/mb84:w pr b $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using tpoofp:f/kg3 7 ;ae 0qche concepts c/k3o7;qf 0:ep gfap oof latent heat and internal energy.

Will potatoes cook faster z7 8wq y)/h+d u60tyfy7yauxxif the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why use jw7q 2olr,:ecit?

Very high in the Earth’s atmosphere, ia)jkcm:y1.k the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed A/rg sr5z2kjhtyx(x5 g ,2id4o rctic expeditions have survived by covering themselves with snow. Why would they do szg5/4 2 rojx5y,di kr(txg2hthat?

Why is wet sand at the beach cooler to walk on t0qy ox27tsi3ey utg7nn8+ iz.han dry sand?

If you hear that an object has “high heat ,a+ akta;3jv gcontent,” does that mean that its tempera a;avt3 aj+g,kture is high? Explain.

When hot-air furnaces are used to heat a house, why is it 2d l ,rugg4p3z6d lay o+7e5fsimportant that there be a vent for air to return to the furnace? What happens if this ve lop7rzlf4g3 s+6y,2ged5 a udnt is blocked by a bookcase?

Ceiling fans are sometimes reversible, ucy0;nt;wx 7hso that they drive the air down in one season and pull it up in another season. Which way should you set the faxuytnc07w ;; hn for summer? For winter?

Down sleeping bags and parkas are often specif5ymbr0 8 qsk9.ha(jya)n)ssl ied as so many inches or centimeters a.rsb5mjynh0))qlysa 8s9( kof loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued o0iv 0x- w:(v j1jc vf.wlhpg7sn top that looks like a series of fins. Why is it fivjvj w p.xs10(vwhgl-0 c:7shaped like that?

Sea breezes are often encountered on sunny days at th10 f.-imuxqq4 (gfh 5**nmmeyd*cwhq h9,eeqe shore of a large body of water. Explain in ligh5ix0cqm,49m-f qq nm* w qd.hh**1yeeugeh(f t of the fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flonf(cj2 +vt1v wr5e s+*yex c*ow is often cooler+ rc5 w+xtyj2 1eon(*vcfv*es than a floor that 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*8w jr; c*c xvg.two3b readings are always taken with the thermometer in the s ;vxwc*b*3j go8rw t.chade.

A premature baby in 7j /uhh6u* bx sf:(9nkra ezj,c8d*ksan incubator can be dangerously cooled even when the air temperature in the incubator isjed7 jf/ak,cuu** kszh bh6 (x :n98rs warm. Explain.

Why is the liner of a thermos bottle silveredu4;icb p. z7fpx.c np9j8pb0 z (Fig. 14–15), and why does it have a vacuum betweennz4xb;j 0i8 .cp7uppb9 czf.p its two walls?

Imagine you have a wall thao0wa8 9qd ojow8aj56 mt is very well insulated — it has a very high thermal r690 aq 5ww8moa djj8ooesistance, $R_1$ 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: ( ywbhd4 hmn l-v0f0yt:vw0))2- klnad1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains red0d t-04v ah) lkwn why)vbfnld :02my-uce which of these heat losses? Explain in detail.

A piece of wood lying i gz30uj9nfmvikbq-0 4yw-/arn the Sun absorbs more heat than a piece of shiny metal. Yet the wood fezf- qgm/r0avk- j0 w9ybiu3n4els less hot than the metal when you pick it up. Explain.

The Earth cools off ajdq dd 3i(v1fk0q 25w7j7 yelst night much more quickly when the weather is clear than when cloudy. W yw7e2 0 djl( v7qdifdksq315jhy?

An “emergency blanket” is a thin shiny (metalr gv(y7nhfbv c+vtc-k8 u0n*3 coated) plastic foil. Explain how it can help utn(0v+*v3 7kf nb8 yvgrcch-to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extremif3bta+5)ns0dqjt2 g e temperatures than inland c3n aqst) b+ id2j50tgfities at the same latitude.

  How much heat (in joules) is required to raise 4ich6lybh7-a c2gq :hj*b )uethe temperature of 30.0 kg of water ic4hb6e a7 :q*-lh)cguj2hbyfrom 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 ifn+ xi*6 79t tpprv sgp;cm.9us initially cgpx p*vrip6nts99 .;7tf mu+at 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 0zvzsnqpydj k7pnfx 0:36 q23Cal 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 (Btun2:w8j i,teyo ) is a unit of heat in the British system of units. One Btu is de28e ojywi, n:tfined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genzcc:i-4 lh9ii erate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is)g(z;v s0m.+oja gxv p rated at 350 W. Estimate how long it will take to heat a cup of soup (avgxgaj0so( +p vz.);m ssume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are94k7g7czz( age j)c6l +ztp bi used to bring a 1200-kg car to rest from a spjtccg pzag+ zb7)( i kez749l6eed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How mucc-f(i 4 y3nghzh heat does it absorb if its temperature risf4c hyinz(-3ges from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 13d vvuk*; vp.p35 kJ of heat is needed to raise 5.1 kg of the metal from ;k *p3vv.uvdp18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, a xaeayrbi7de.w ul a6( eju*qs6 j+.3j6mk5-pnd water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of th7u mexau+j r 6(j-i6 kw3ybse5a6d*j ..eqlpaeir masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomety( fd +;vof6 wkk 81lata(; 7ig6wyqtjer 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 blowf h/fs l- frewg2tz9a.l,ykp5y 9,dn 7 12iiwck of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (mass .q ,kf.knna csi01porn / p69z= $0.4\,kg$) 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 izttzz*kg-bfnbdc ert/k-3*q0 8n s ;9s 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 to bri)ajw 7iso3 hmn5mup4q: j/0kmng to a boil 0.75 L of water initiall75ho s40qmmj wupnm:)j 3/kiay 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 c yw )iikv-(w6nandy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calori(i)w-nik6yvw meter 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 ofc2hg8 nw y)c.u iron 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 5a c*(y/ nqmifa 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 theg rw*vy tl*8q1d fz4)y amount of heat needed to ra zf1l4rw dqt**yg v8y)ise 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 yn:p:yo4 lf3a melt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from + o.cijzl/.g kthe roof of a 45-m-high building. If 65% of the thermal energy producjglo.+ .zk /iced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a personkmwv81hgjn s;o;t4q f2nk p9 ( may give off 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has been lost? kmw gnj;v4f ho1t n2 ;9(8skqp   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 melti4onh(sk k2 +lhng point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vlo(h +4nkh2 skaporization 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 fa2a pn yly-i..rom 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 ob u r;exud7 2lj+5ran -8nzc0of 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 8u84jb ze,cs+9cygg; dr -)o jhh:wzwiy 5/aiL of water over 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 rid/jic:whe4y8 sbhd5iw a- g)j,g+9z;uo r8 cz yer 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 at2 fhy(b.af u7t 100$^{\circ} C$ must be added to 1.00 kg of ice at 0$^{\circ} C$ to yield liquid water at 20$^{\circ} C$ ?    kg

  The specific heat of mmv8 :2l6hmra 5y rmyj*ercury 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 ath c2o4 nrb1bu nyk/a4( $250\,m/s$ 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 7f--m hn *zttcat $6.4\,m/s$ 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 investigato7d:l1e,dwynyog-l)onr5 ;kpm f*xa 4 r notes that the 8.2-g lead bullet that wa roxdym:nfkoa,*7n4y51 llp;g -)d ews 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 diameter of 2.0 cm is kept atn uuon5ddk3/8 460$^{\circ} C$ , 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 conduction in Examkll s8 u4*elfj5)w3bo ple 14–10, assuming that there are strong gusty winds and theljw)k lb3esufl4 o58* external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a0fm in7n07ei7p8bs q4vej2 oz tungsten sphere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat flyy1m9as:8blnk ,:xp bv0:f lvows by conduction from the blood capillaries beneath the skin to t lnx k8p amvyy:fb9:0v,1sbl:he 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, share a 12-cmp20 qiwpu ncglovp/xa 3b* xe u1 a(xp6b4+b0*-thick brick wall. Because of a number oup pbxp(uwaagxvno pi *+310/02 xb *q4ce 6lbf 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 melt a block of ice at 0w jjzlg; 779ug$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sectiof*./ qozuf 0fqnal area are attached end to end (Fig. 14–18). The copper end is placed in a qz0qf uf /.f*ofurnace 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 Eaa(.vcas tr q),.py/dn rth receives energy from the Sun.t s dn rca,v.q(y/p.)a    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of heat, which is dissipated through an(kaei r. l.(x glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the differ.ra.( xnie(klence in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come m;xjd1*vv7 o2 x)fuxoii +si 1sainly from a 4.0-in. layer of brick anuo * 71s)io;12+ vxxfjivd xisd 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 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 separated by an air sb)o *sj rmyu:2ebw--zpace, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction is g bzmyuo j2s:w*re b)--iven 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 ice at jz*tmv/ r 8q4er)hau-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 liquid bm1o:-bun iap;u1(wdfg ,e/y 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 mvi(e*40dce 0owgd qi* uch thermal energy is contained in the world’s oceans, estimate the heat liberated when a d4e*wigce*i00q o(v dcube 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 firi+6 xegha1zp /vgww 7t2ng 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 taz7+/hxpg gw21w6e vsystem 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 i9z t1 hg0kybr+t to be a perfect emitter btr0 kg1z+9hy 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-m2s *pphcf 5f)kg person 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 t3dvd.b v5wtexj /9 zt5c6pc8qhe top of a cliff and falls a vertical height of 140 m before striking the ground. vjqd x3de8w6vccptz tb.5/9 5 Estimate the temperature 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- dno qz*7by:qat:42gm L insulated pail of water initially at 20.2zbo :yn74dam*:tqgq 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 shq8 1g+tatok3 urface area oq1g a3tk8h+t$1.2\,m^2$ 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 +-9: pja -3l*z-0fnl6j aekmtetc lhpof 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 conducted from the interior of t 8 bav-:porek0he body to the surface. Assume that the thickness of tissue is 4.0 cm, that to :rvkb8- pae0he 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 conductivit/oelkwd)e u9s j 5g)1aynd- dm(v(+qo y of air) and areay)v(aj(u osk) g e me+w don1-5ddq/9l $410\,m^2$ 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 trav/0 :ccum ,bkw8l wjhc: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 radiati.)wv0z, je obwon from the leaf to calculate how much water must be transpired (ew.j)zbe wo 0v,vaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite mex/l/ p*x/h21n yfttdk lts when it enters the Earth’s atmosphere. If its initial temperature was -12*/tk/ptd2 xn l/fh1yx5$^{\circ} C$ 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 w3 kz: 8+ r-a09dwtdcor1xn hx1.0 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.l/c7;h(ax1,qgimge7,qs y rq 14–22), two people hit a soft rubber ball at a wall until they are about to drop, 7/(rh qgeq m7glx, asqy;1ic due to dehydration and exhaustion. Assume that the ball hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masses of ice at ;waf u;uo:q;5fjm ;tz0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose hewa db5145f nzr)18yu9c f ntvcat by conduction and radiation at a rate of about 200 W. Estimate how long it would take 1c9tf41n5aufz 8dw 5c ryn)vbfor 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 disj4rrn3 n7 yp 8duoc,d.8g-5s6j ezxi whwashing, there is “no hot water” left in the 50-gal (185-L) water ynj88dres7pr-6.oinx,zc5w uj4 3 gd heater. 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 g5dy. h9/o9sl xy v9l(boygi)ylass surface 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.    $^{\circ} C$