What happens to the work done when a jar ofw hia/t .fa7r6v8o7 j nj.4iqc orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flowpkv3h+em u*+ t between them? Are the temperatur *hk pe3tmvu++e changes of the two objects equal?

(a) If two objects of different temperatures are pk43 jhcc7si6klaced in contact, will heat naturally flow from the object wit64 cc7ji3 kkhsh 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 temperatu(yh;2a0w s zoi1tkn9hre may drop below freezing a few times i9 oanzwi2 ;s 1h(thy0kn the winter, 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 large. Explain why this fact mak 6ov )w:plrn(fes water particularly good for heatinlfv n6:r (wp)og systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the )r-oy uyp/(n w5l (z uetuw1i/cloth jacket surrounding theyi )1oep/uz5ru(t yn-/w( lu w canteen is kept moist?

Explain why burns caused by steam on the skin (k2 r,m bbeq9q;kp0 ngc+orm/are often more severe than burns caused nk0 bkmq 9rc+(or;/ b,qpg2emby water at 100 $^{\circ} C$ .

Explain why water cools (its temperature dp y0m)rxz nv7-rops) when it evaporates, using the concepts of layp)r0 7m zvn-xtent heat and internal energy.

Will potatoes cook faster if n dr;(q lr1)ek-k xf h*0adj+bthe water is boiling faster?

Does an ordinary electric fan cool the (1+7t8f3ih-gzd f6x rbpdxsh *. zs1qxiaqw2 air? Why or why not? If not, why use it?

Very high in the Earth’s atmoa7 (q 2ww) c:nkguqe;xsphere, 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 survijr)beq(da 0g+d: iy vo3avp);ved by covering themselves with snow. Why:v+aq 3de y vogajdip ;()b0)r would they do that?

Why is wet sand at the beach coolbqp8 dte rv,yg+g9+(k er to walk on than dry sand?

If you hear that an objec 1c/f7bkaprtzu59,i-3o e f ilt has “high heat content,” does that mean that its temperature i i9 /p-3,tzl1c5 bfrefokau7is high? Explain.

When hot-air furnaces are uselo52 bbwjx*ldbg*p lin* , :em;ow 3v9d to heat a house, why is it important that there be a vent fow:l vbdbjm5**eg;2noiwp ,ox*l lb39r air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reve/z95rl:igmq*hwf gb8fow)- l rsible, so that they drive the air down in one season and pull it up in another season. Which way should you set the fan for fzro5-gm/):gw * fbw9ql8lhi summer? For winter?

Down sleeping bags and parkas are often specified as so many i-fkp * ma)l1amnches or centimeters of loft, the actual thickness of the garment when it is flum 1mf)ka-*alpffed up. Explain.

Microprocessor chips have a “h2 xbcmdolu462k*t af30dgpw- eat sink” glued on top that looks like a series of fins. Why isl3od a -2pg *6wbd0tfu 2m4xkc it shaped like that?

Sea breezes are often encountered on sunnnyq mm++)fidb1::dc wlqdn0;y days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more rapi;nd n++ )mbqlm1y0wi:df:c qddly than that of the nearby water.

The floor of a house on a foundation c ansuh-y+myuxo+1yzei/7 -/ under which the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundation). Explain/ cyo+h/-+-yu a nseux 1yz7im.

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 sw6 3fky6rye6b6x p5b with the thermometer in the shade.56r3e f xyp b6sybk6w6

A premature baby in an incubator can be dangerousov(*ls bf i8g-z),xpra*maai+ .v7u sly cooled even when the air temperature in the incubatogsr iap -sbv)u*(*v,fix 8amz+a l7. or is warm. Explain.

Why is the liner of a thermos fh3 k3zm,bhn80w, 8v f5k cdxvbottle silvered (Fig. 14–15), and why does it have0v,kmxnkbh,v33 z5h d88fwc f a vacuum between its two walls?

Imagine you have a wall that is very well insulated — it ha 9n/9k cej)pfcs a very high thermaln /c 9c9ejfpk) resistance, $R_1$ 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: ( p1myrjhuq3)51) 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 mechanih ujq1 y53)prmsm(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying inq3dy t nbcg:4rek7anfj d+1(* the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than *n+rt aqcb nk41 :7y(je3fddgthe metal when you pick it up. Explain.

The Earth cools off at night much more quickly when demh41dwa4 3uthe weather is clear than when cloudy. Whyu aehdm434d1w?

An “emergency blanket” iszntwe1 *jwd/ , a thin shiny (metal coated) plastic foil. Explain how it can help to keep an immobw t*j/w, zen1dile person warm.

Explain why cities situa*m, d,h(h hq6zgh 2luq3xgkm)ted by the ocean tend to have less extreme temperatures than inland cities at the same latitudegmhh)*d 3qugz mql ,(2hhxk,6.

  How much heat (in joulesulcks +5xr; kxua 88+k) is required to raise the temperature of 30.0 kg of water from xu+skkkx; lca+ r588u15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will s8pyn 6z z+vh42*i vy5zod l*a7700 J of heat raise 3.0 kg of water that is initially at 10. l5 yp6s+2vyzhaozd8** z4inv0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes abobxq/2 q r0wl d1or+;pzut 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 uniu*bdg,gq(:l odph8 ) vt of heat in the British system of units. One Btu is defined as the heat needed to raise),:dp dhbg v q8lou*g( 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can g6 mtn0)qfhey 3enerate $32,000\,kJ/h$ 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 3det a)0g1j5 cb50 W. Estimate how long it will take to heat a cup of 1j5td )0abecgsoup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when th2 n /9cx2rneyavq. v)0y1o jxze brakes are used to bring a 1200-kg car to rest fr9n 2yo/az ).vjrq1 ex20nycxvom a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 +gs*mcw qeq;+2y+ cvqL of water. How much heat does it absorb if its temperature rw+ y2+cme*gqq; qv s+cises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal sc:8fdz ; ye/ll6y;mdvubstance if 135 kJ of heat is needed to raise 5.1 kg of zmc 8y;6ed/:l yvd fl;the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, alumib l:0siuq5 , l8txiu.nnum, and water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their massesl: i.lsu 8nqi5bu 0,tx? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomyb7epmp wy+)/mbim ,. eter 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 block ofvovn2 71k71p loz nx1l 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 (masunpq 8eo1 *pt*+x l7des = $0.4\,kg$) just forged (Fig. 14–16), is dropped into 1.35 L of water in a 0.30-kg iron pot initially at 20.0$^{\circ} C$ . If the final equilibrium temperature is 25.0$^{\circ} C$, estimate the initial temperature of the hot horseshoe.    $^{\circ} C$

  A 215-g sample of a substance is heated 9js+jz,/,z4nxstrm o 7arr-eto 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-Ww,li. +xjmqj+,f -eta coffeepot to bring to a boil 0.75 L of water initially ae a.tj+jl -qi,m,+xwf t 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 fr; c.)hrkbix7 lom 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 calorimeter cup of mass 0.624 kg. T )hr7il.b;xkche 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 iron4* dhhct4 p/am at 180$^{\circ} C$ is placed in a 95-g aluminum calorimeter cup containing 250 g of glycerin at 10$^{\circ} C$ , the final temperature is observed to be 38$^{\circ}C $ . Estimate the specific heat of glycerin.    $J/kg \cdot C^{\circ} $

  The 1.20-kg head of a hammer has a speed oft3u p .;nv2o njak:q)f $6.5\,m/s$ 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 definq7eddl5jdl pq;nj/ h e63 97yded as the amount of heat needed to raise its tempeled5jedn/; 7d9l3 hdpqq6j 7yrature 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 thatun4b f*9 no fwwpzs*6k5;iv2a is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium spherhi+ czv5*0;c /53yg qld vtl 9j.szbebe is dropped from the roof of a 45-m-high building. If 65% of the thermal ener59i3v +vehl;c0dtbq/5*s.y l jb zgzcgy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may givrw ;4yltbwequq, -iikpw31z(,( 4 o kie off 180 kcal of heat in 30 min by evaporation of water from the sk 1y,iwqzuwb kp4wi- i3 k(o(rqet,;l4in. 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 insulateqsw;3bb;teqx6 cf9q s4tf v-/li 45lad container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heatq4csbq36vl ;tqxs/-5taei;f 9fl bw 4 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 freh)g yfsrt2vpd2:y 2trj12v q2jh 2zk,ezer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains 830 kg of water at qoa,r0g uy vk wz-3f,t72t ax*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 conszpvid 5 wgs7.4 h1lkzf/1v 4uwumes 8.0 L 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 rider is only about 20%, most of the energy consumed does go to heat, so ougv1h1dz7/k5ivlw4zuf ps 4.wr approximation is not far off.)    kcal

  What mass of steam atnl1xs8+tc :ru 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 mercurokqxca(imwd)m qh5 7x4 o1 y93y 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 x-rcgwfdyk2w6h ,)g*r(+cfps t ap24l zk(r8 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 movingpz:b- 6plu mi-p5kb3l 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 meox 5ml*3*a ujj,1xq that was stopped in a doorframe apparently melted completely ol1 5oaxj*,me mxjq*u3 n 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 i k*b:ws/;m opak1n:j-mjxr/ rod with a diameter 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 zlw vt2b*a*w)conduction in Example 14–10, assuming that there are strong gusty winds and the2) tbwz*wv*al external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiate)ixy;j duov mdf6.;7h d by a tungsten sphere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat flows by conduction from thexz p/i4cdis;/n)*oq j w1z+yxb ns4 ,t blood ca4ni,jzx1/;*poc zxn/it)ws+ s4db yqpillaries beneath the skin 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, s7rntf-:mbf0 g1y mi)k) bh j+lhare a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one ro) ff7 ijk bntbg1m0:) ly+hm-rom, 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 wuq k1 -0ux:0 jf+gwliat 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 t4p yf (s+uk 9-xx*za)yyn ef,ihe same length and cross-sectional area are attached end to end (Fig. 14–18). The f*a- sxuy( yfn)+y,i 9xkp z4ecopper 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 5szy;sjzxmu; h+- af.r(kfynkqlq)/ v..z1 fconstant, estimate the rate at which the whole Earth receives energy from the;r/fh m)n ( ;q.q+.s y1zyu kvfas-jzlf x.5zk 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 generates 95 Wncsicp/f13qd(z7h dwf; )u4 z of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm th4(zifcdd;/3pc )fnwhs 7q u1z ick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualitdyd*.n qa-4iu 3ms4 v5lq*tg aies of the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, as shown lum.a35nd s4gtd4*viyaqq-* 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 glas+nyln52k hznk; si,e1s separated by an air space, Fig. 14–20. (a) Show thalnez, + 2n1yn5kikhs;t the rate of heat flow through such a window by conduction is given by
$\frac{Q}{t}$ = $\frac{A(T_2-T_1)}{l_2/k_1+l_2/k_2+l_3/k_3}$,
where $k_1$,$k_2$ and $k_3$ are the thermal conductivities for glass, air, and glass, respectively. (b) Generalize this expression for any number of materials placed next to one another.

  Approximately how long should it take 11.z chqd)m3f01 fh2-hl m0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0.20 g xqx u 7/ruhkdh,2jc; r+z19gkg 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 energy is contained iayu4g9 8y9afsn the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on eay94y a8g9 fausch 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 of wood with apbporo5hoi; )g g.a1/ mxa;(i mass of 1.05 kg. The block and imb(;x i1 )pphgooa5r/i. bmo;ga edded bullet 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 into space by the Sun, assumb6+z nvp,fgof7* ku;f ing it to be a perfect emiffz kpo,6f*bg;un7 +vtter 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 generate04 e6 kzc:idjt $200kcal/h$ 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.xqdd 9ib /vfu93hnk) cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the.ibdd9kux)n 3q hfv9 / rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated p1ruqf.3t 8.oxtet g7yail of water initially at 20.t1egt8uo3 y.t.r fxq70$^{\circ} C$. 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 t np)t2(.c4 lvd k2jbylhick with total surface area ).b c2vp( y2jd4ltkl n$1.2\,m^2$ 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 8a8w 9oj/ndc san 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 heat can be cj jf)ams,-z p6onducted from the interior of the body to the surf,fp-m asz)j6jace. Assume that the thickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thick (assume conductivity of air) and ,h-c0 h a)/i--s hyur2f mnnxzar--c2n,yrz x/iu mahsh 0hn)f-ea $410\,m^2$ 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 q w5n4e-g)ra9jtt5 mteling 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 ra6n9ua/w8 cb3fbqins1wu i6 c*diation from the leaf to calculate how much waterwwiu93i bfa/nn*b1c 66qu c s8 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. Ifskcw 2)ft*m2 v its initial temperaturec tvs*mw fk)22 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 withinnfbqjvu 5uh5j c7b 7y: ru2q06 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), t:/1xnymjz e w8e/hixn4 9v2hq5d ) ennwo people hit a soft rubber ball at a wall until they are about to drop due to dj)2e81nnhqze/ni5nev4h:wmx x9/d yehydration 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 p51bzea:x6 c z 3tneo mt71dg0result when equal 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 con3sca9c3+l*zzyl wu+:w 0d tdfduction and radiation at a rate of about 200 W. Estimate how0zl 9+d+ :f caytcdu ls*z3w3w 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 water” left in e1+,u.) hrjl +awmsjl/0 png athe 50-gal (185 0 g)ruajpl/w.+sn 1mlhe,j +a-L) water 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 glass surface of a 60-W lightbulbpwe r4h )99aka 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.    $^{\circ} C$