What happens to the work done when a jar of orange juice is vigorouslyus913r gn m5 jbtf)z0g shaken?

When a hot object warms a cooler object, doee+ocu8yhlw i6)+eqa1 g ek56 ms temperature flow between them? Are the temperature changes o)ocg +6 ek+q 1ie58eya6muh lwf the two objects equal?

(a) If two objects of different temperatures are placed hxa2jjtmcz zc:21g,74q m4a b in contact, will heat naturally flow from the object with higher internal energy to the object with lower internal energy?4am,2g tq mh24zz jc:j ax17bc (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 mp8kvi;(r,b z b/3iv igon0 9ytemperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by w0gi yi r9ivv,z b3m/(;k8pn obatering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes wa- ws0hccc3su q09 qht7ter particularly good 0-wsqc0h u 9h7ctc3qsfor heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surrounding th echw7/ys1b;ke canteen is kept7/s 1b;kh ycwe moist?

Explain why burns caused by steam on the skin are often mo+zg9; qtdoj5s9z p 3ilre severe than burns caup3s lt jz+di9q9zog;5sed by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature dmlyzu;;: . qn)+ldfi(tq mvh 8rops) when it evaporates, using the concepts of latent heat ;ymqnd; utm l8fzilv.:+( qh) and internal energy.

Will potatoes cook faster if the wassirku58we --ne-; gy ter is boiling faster?

Does an ordinary electric fan cool the air? Whyj*jr fj kr-q cj;f/zz lv4c)o)e+d9 5l or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can be 700 kyw7x *8x.*gjsgcj 1a*r .mir$^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have sum h*gjvapi94dw/r6 9 crvived by covering themselves with snow. 6/wc 4 i9j9hvrd gp*amWhy would they do that?

Why is wet sand at the beagpw j1:9+m tdzch cooler to walk on than dry sand?

If you hear that an object has “high heat content,” doesyvqcs0us59d4td7t , +w(o ssa that mean that its temperature+u( cq7s0 vs,tds5two4y a9sd is high? Explain.

When hot-air furnaces are used to heat a housn lcvar43*e92w8sb k p.8 ndkke, why is it important that there be a vent for air to return to the furnace? What happens if this vent is dnwskepb c 8.l* 84v23rkk 9anblocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in v.tdccn0f)1 +k(jp rn one season and pull it up in another season. Which way should (jnv cpcr 0 1nf)tkd+.you set the fan for summer? For winter?

Down sleeping bags and parkas are of2ee)s6s en1k ften specified as so many inches or centimeters of loft, the actual thickness of the garment when i)e2k6es f n1est is fluffed up. Explain.

Microprocessor chips haveyy-ln g+rcs3 .k jae)- a “heat sink” glued on top that looks like a series of fins. Why is it shaped like thayj 3skrcn-+)-.l ygae t?

Sea breezes are often encountered on sun xe7t3ojd8 ev,m:lt, ony days at the shore of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that of 7mov o3,t: 8xt ,jdeelthe nearby water.

The floor of a house onffno*oxn64a l,xs8 x3 a foundation under which the air can flow is often cooler than a floor that rests direfx,fxx3os4*lo68n a nctly 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 r5r xullz 193jy0e3 yiieadings are always taken with the thermometer in the shade0 yzrlul3 e iix915yj3.

A premature baby in an incubator can be dangerously coolem,y nd6r:/(rwovxe2g kp(c8 id even when the air temperature in t(2e( grw do,r6nmx:/yk 8pv cihe incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it kt oua8ppi.i5 0.3yqzsi2re+have 2 rz.sp.3t0 u+aqip8ieokiy 5a vacuum between its two walls?

Imagine you have a wall that is very well insulated — it has a very ovoilng9)8 .* x(avsqhigh thermal resi )v goxi(lnoqv*.s 89astance, $R_1$ 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 thegx fgp,t2;3n;hvd9j: lenzvras:8 * i following processes: (1) ventilation around edges; (2) through the frame, particularlyd8 3*ve2h:zxaf tnvr9ig jsg;p:,l ;n 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 more heat than a piece of shigqye;z0 /fm(lny metal. Yet the wood feels less hot thanmy( fze l;q0g/ the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather/e:xm7v+ykg q is clear than whenv+g :7/xek qym cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic fj78ayl fj xb1ms55ff. oil. Explain how it can help to keep an immobfjx.7fjm1a55lf s 8ybile person warm.

Explain why cities situated by the ocean tend to have le/xy,j(1 s,xb(ms9 apfy 7*dd*4luqwhr-u af pss extreme temperatures than inland citiymxub 1a,f9w d/,j q yfp (ss -hlu(x*d*4rpa7es at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0 k fg6or5 a;phl2g of water f; aplor256 ghfrom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7x.d35g et1j el700 J of heat raise 3.0 kg of water that is initially at 1tgel 1ej. d53x0.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active pejl y ,-8/qsus r+u-gxzrson consumes 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 ot)v;;;.vh5g 9zxerp pf aorm6h;/plp f heat in the British system of units. One Btu is defp p6;fxp ;ot5z);l mgpvehv9arh /;r.ined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generategq1 ;,u37vuv qlg c)m:ab9o,bh)lrpf $32,000\,kJ/h$ 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 c (rcyz/qvk2kcz x. ydj02e-+long it will take to heat a cup of soup (assume this is 250 mL ofyc(c/+z 22rjvxdqk .c -zye0 k water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are uzvb0v,fvf /(d;3+doa kwsg :ssed to bring a 1200-kg car to restkd,v f03fss/ bz;dav:g + (vow from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L ofsjr mi;)+ 38;g fdaf613yov vdldnz,w water. How much heat does it absorb if its temperature rises frodg,6i3ld ;1yj )m+zswvf3v 8d;a rnfom 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substa ncdl2fb9bx-e 77vw9o nce if 135 kJ of heat is needed to raise 5.1 l7b92n-v7d b xe c9wofkg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, alumin( v6ldna19 dwoc8 hq6fum, and water experience the same temperature rise when they absorb the same amount of heat. What is the q(dh6c 9 6n owdl8vf1aratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 7r)t7 vz0yg+ctraqp+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 temperaturedr/d/ rs-. pm-:q y5 k+ih+ eh8ezuzzd when a 245-g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (m npl7hv 0qf d+vn)dw3+ass = $0.4\,kg$) 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 substag10z kw 3ix+vv9md8uance 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 towlggo p9 *3/j +;q.7phsvj gwt bring to a boil 0.75 L of water initially at 8.0j.v 73sgo;j 9whwp+lggt p /q*$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy from uwrh ahxi. x 8nb9(42cou a/q9the following measurements. A 15-g sample of the candy is allowed to dry before puth(/ubnca99x aui2.r8 qwh4 o xting 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 at 10a.4 gtnb +*be-u8bx rat 2qmn80$^{\circ} C$ 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 suh xwa 05dr w4ksv4 w4vez5g/2peed 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 defn.e73do b7 vy-1fzevkun7l *p ined as the amount of heat needed to raise its temperature by o.vbvez 73u77ny d* -pkln1ef1 $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 t9/ksnv l-h gz,5v )gzis initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped frock+p3d(bsd b xg2o8e5m the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is abd8dbe 3 oc2gspkb+(5x sorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may gy9,:kwn4- wqsusa7 )7m flua 7lbakr8w)qw 3xive off 180 kcal of heat in 30 min by evaporation of water from t) 4 ksl3ak,waa8x)n bqlymfq-w7w:977 usurwhe 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 poiny+)dmk29ltcycebrncoc p;2 c h+1sbp+e 7 s29t 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 vaporization ;l2 1++d+or9c 2kbhcy)ep7p nm 9 bssy2eccctof $200\,kJ/kg$ 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 free 1qkv*x8r-w q.vva6 tzzer 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 8w1e/q,+j d-dww9 uxr+ mvp /bi30 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 consumer00q re+9nkjw e /ox8ns 8.0 L of water over the span of four hours. Making the qxo+ej 8kw0r 9rn0 e/napproximation that all of the cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam atfzby7b8 o h9 3x q3 6+0yavj9vf*uiicm 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 mercury isvte;na,zl;5i aq- xcjgcv- -nx /ju-hg4w.w* $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 m cb5zvv:b: 6fat $250\,m/s$ 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 mofq hb7s)am)t o 3z9kd:;uw:xzving 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 le5pyt s;pov -2yad bullet that was stoppepsypt; 2yov5 -d 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 di4rak92sgh - i9 2u1xalz41c jnr9ndd mameter 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 conduction in Example 14–10, assuming th/7( nxv2v;gbf ds1jrr at there are;2s bg7nr(xrv/fdvj 1 strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power i 9yy k)p ds,int68;mpns radiated 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 f duzv)1s) k20k/kn kbbrom the blood capillaries beneath th bk)b10 d)kku2/svkzn e 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 peqlzd6y/ .xm q1ka2 v+cmw t;o,r side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the a,ayk;vm6c dzt o2/w+.ql x1mq ir 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 tt vud5p89p5k ee79bn 3hqky8fhe 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 ok+l+pag598ls*f tl)7 b axr.vtbwd + af the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant ts.*b9+xlrlt tdfv 5+k8p aab lga+ w7)emperature 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, estimap9udt31ai .x 7m4dc+aizv ip .te the rate at which the whole Earth receives d9tvacdu piiia ..z3m4+1 7px energy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of heat, which is dissipated t1fkqq 18qd;t3t o (nmkhrough a glass bulb that has a d1tnfqkqq;m( 3t o k18radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come -x weh3fp5l+yxti7er. qa*/c 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 oq*.5i+wcf7xeha-lp xyter /3 f 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 sepuj1m 7dc)u7 mg pse8g,on hz44arated by an air space, Fig. 14–20. (a) Show thatd7 mhupogc4,874 zem1)sugnj 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 11.0t fqhds zo(ib,*8m6( o 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.:l zo 7hwad8jotz j62;z.,i-v/ ouiye20 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 energy i,-2o--gm7xqsam. t m h lbu,gkf3j:a.or d )kls contained in the world’s oceans, estimate the heat liberated when a cube of oceag) l,-of tuj:h omdlkm7 sxm-a,k ra3.-gb.2qn 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 of wood withms kzs+ r)40tw a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reache4 w0z)mrsk+s td, 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 powern( nj)vga 4 b4gatm,-ogh/9rv radiated into space by the Sun, assuming it to be a perfenonrv 4g/ah- )(ggabtmj9,v4ct emitter 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 peru04(hz 9odb (ibd(uhv son 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 the top of a cliff and falls a vertical d h 1jw3zrd/c6io8h, pheight of 140 m before striking tdz /i6ro1j8hdwh3p ,che ground. 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-L insulated pail ofu3;j 6p+taioe4qra5q3g0u2 i kr h2mk water initially at 20.qr6p;3+t5oare2gu4qua3k0 jihmki 20$^{\circ} C$. 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 weax -z rm78ie;hrul*a (nrs a goose down jacket 3.5 cm thick with total surface area a r8e*l;z-h(7mun rxi$1.2\,m^2$ 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 a 3oqkzj (b,g-)ys3z0d cz5n ecn 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 hq*qtfs o2o1y 9 eq3skrf9-2lby bp14feat can be conducted from the interior of the body to the surface. Asrfk 9f1yo4-qyqp *qo21l 93fsst2bbe sume 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 conduyyim4f,vtox7t6j8- e ctivity of air) and area ixm 6fvje8y-o,7t4ty$410\,m^2$ 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 traveling atnr g t7pt5.jne8 ln0k( $220\,m/s$ 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 axiyjg9 .c5ty1qaa y/bd-c.z 2ccount radiation from the leaf tc5a2 yica9 tx1jb.-gqdz/y.y o calculate how 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 w v9b dp-85v;yr6dcfew hen it enters the Earth’s atmosphere. If its initial te9 eb 6yc rv8vdd-fw;5pmperature was -125$^{\circ} C$ outside of Earth’s atmosphere, calculate the minimum velocity the meteorite must have had before it entered Earth’s atmosphere.    m/s

  The temperature within the Earth’s cxof m cj-d18ss6 ,*kqfrust 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 rubbw06 ;whnfz1waer ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the an6 0wzw;hf1wball 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 result1 zw3hmp(sl x2 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 conduction la 1ogkx ux8h92x qz3l:.rcp8and radiation at a rate of about 200o:9lg lrx21cxz . 3xhp kqa88u 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 water”4qjy0s2tgfdu k 61c(qi3 5xw z left in the 50-gal (185-L) water heater. This suggests that the tank has ezs3jf5i (42q uq ckwt 1dygx06mptied 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 o flp :vkh5a kts:d.zp,(,wc8cr :- nl60-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.    $^{\circ} C$