What happens to the work done when a jar of orange juice is vigorously sz /vtxeo,(cq+*exl 8kc(pvf * haken?

When a hot object warmbz ()4l6z8ca0qk:us( afy7hh5axc lks a cooler object, does temperature flow between them? Are the temperature changes 0 5 habkfxha( uqcky7 zcl486al ):sz(of the two objects equal?

(a) If two objects of different temperatures are placeqf4l +s) 6m, hm4yxuhed in contact, will heat 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 if the internal energies of the two objeclmf + exy64h 4uqm,s)hts are the same? Explain.

In warm regions where tropi,mtmvjm )(nc;cal plants grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitivmtn ;m v(m)c,je plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is qu 3s*eg0er2isf1 ad +svite large. Explain why this fact makes water particularly good for heating eg rv0*+3sf2ai1 dsessystems (that is, hot-water radiators).

Why does water in a metal canteen sta jg- 41hg0esyt18vixju eef0* y cooler if the cloth jacket surrounding theeju ef8e1 gv4h0xj 1*- y0gsti canteen is kept moist?

Explain why burns caused by steam on the skin are often more sevep)6b (klx qn;-8 q 2njie 4+*ubifgaxbre than burns caused by water x );*f (6bb q ji2uli4np-neqxag k8b+at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it m+tr p, mygvz9a-5 o7nevaporates, using the concepts of latent heat and i5a7-zyrpm g ,+m tn9ovnternal energy.

Will potatoes cook faster iida 6(qgepp bo5q/:sb 46r- ekf the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, whglj j2ep/e4amv))e9 qy use it?

Very high in the Earth’s atmosphere, the temperature can be 7007c;hvz hh fsv c(25y0b $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have surviv)ur:s 3nn9 s29yv vhjved by covering themselves with snows3hvs: jnr)29vvny9 u . Why would they do that?

Why is wet sand at the beach cooler to walk on than dry sand?d 0yx5iyc(x2 1 q l:p 1f3gruxm3riim-

If you hear that an objectaf.t ux)cez; 4d)s 3qb has “high heat content,” does that mean that its temperature is zqutx s a;b4fd. e3))chigh? Explain.

When hot-air furnaces are used to heat a house, why is it important that thereurfv7h +u )l2i949q0ywu wrsq be a vent f4 yq2u0)s hu9v+wwirf79l ur qor air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in onex/s:w2sye+vkt0av w yb8(l5 q season and pull it up in another season. Which way should you : le/k wsxt 5(v2y8wsyv+0bqaset the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches or centit5msmw j(2ig- meters of loft, the actual thickness of the garment when it is fluffet imgmswj(2 -5d up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks like a series ofp s mb l16f su*3l(7xrlhhip4: fins. Why is it shl3 :mpf l6 shph1rb(x4iu7s*laped like that?

Sea breezes are often encountered on sunny days atgxfkm:v d- mi dnqm,9 )*;fvm9 the shore of a large body of water. Explain in light of the fact that the temperature of the land m dg9fvmx9- m*qvf;d mk in):,rises more rapidly than that of the nearby water.

The floor of a house on a foundation un z1h6m8wqk2 flder which the air can flow is often cooler than a floor that rests directly on 8mklw f 6hq1z2the 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 are a9nh,)q tepw,l 9x5)e h5otobalways taken with the thermometer in the sha9eqbo,9)e55 tn l,ohhx )w aptde.

A premature baby in an incubator can be dangerously cooled even when the mi 22;4jfn kjd1dqk)o air temperature in f 2;k4o)n2dikq1mdjjthe incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (t7950jnpiqubly/gav4m c z: *Fig. 14–15), and why does it have a vacuum between i05incvmzjuap:b/qt* g l9y 47ts two walls?

Imagine you have a wall that is very well insulated — it hasyof6 bc6aao0-r5s b 0q a very high thermal ro5a6 -0ba bof6 y0rcsqesistance, $R_1$ 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: (1) venti .8 4bdmar;lev,dt1r3i0d jyklation around edges; (2) through tdrikyl bd3d.4m, ;ae j r8vt01he 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 reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piecfe* 9k/y **m xfpqljyf,nn- 2he of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Expla*fy-/n9 p*fy*jk2hq l mnfxe,in.

The Earth cools off at bqgeag05a2l 7x (fy6 h,rt5g gnight much more quickly when the weather is clear than when cloudy. Whlae(5ag,hfy0r 2q5gx g7g6b ty?

An “emergency blanket” is a thin shiny (metal coated) plastic gxzp5 ykjdk2d9u 6ls3xoee ( p2;;mq:foil. Explain how it can help to k6qge:kp2kse2;my zxd59 ;ul 3dpjox (eep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme tempertk:7d:1ho iosatures than inland cities at the same latitudsh ::dtoio1 k7e.

  How much heat (in joules) is ri 4ls phim0t epu4g (gg53/)hfequired to raise the temperature of 30.0 kg of water fri0 i/tp5)4 ul3 h 4gepg(hsgfmom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat rai phd*g4u)/hs ::kibl-: wask hse 3.0 kg of water that is initially at 10.:w-)gh ps/h:sdu*klh4b:k ai0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 250z bdg//j8 do8gsc35pp0 Cal a day.
(a) What is this in joules?   $ \times10^{7 }\,J$
(b) What is this in kilowatt-hours?    kWh
(c) Your power company charges about a dime per kilowatt-hour. How much would your energy cost per day if you bought it from the power company? Could you feed yourself on this much money per day?    dollars per day

A British thermal unit (Btu) is a unit of he n. smtv3 lmpn-z*2enufmb83rju72 /wat in the British system of units. One Btunm23-w7mmu3vs f/8u n zb rjet.2np l* is defined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate 2vn 9k 1ip;hig/;ujfe$32,000\,kJ/h$ 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 Wgbn9clv bqv43h6ihpo( 2( am 5. Estimate how long it will take to heat a cup of soup (assumevno9g (h b hv25amp64(q3b cli this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes ar7yw5d i;fq hmu cmfi+u9o6-ur +18i;1oov mkie used to bring a 1200-kg car to rest from a spe -iumduuvmoi 1oy8cfko+ r+9;f1 5wi67q;mhied of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it absorwc 31v4/z ,qc*iz,7 wt2obe u;lnbvj jp5w4jeb i5,bj3woc/z4c pqvi1;, elwvbzj 42 j 7tu* newf its temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metah r1gwr7 4at7bl substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 1 hgwra471rb 7t8.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperatur3i9o r qvj.a/vsiu1e(a60 x j1b zwg;qe rise when they absorb the same amount of heat. What is the ratgw0jvu 6 (aavrs xio 3;jebq.i19/1q zio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermomet 4eizk0ab/ tfp 3+pp,fsn3hw 3+qex t2er 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 of c*b4w y3b/cvfs opper 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 (massc(*0c sxq b,unw9 vl w5ndeh4x h-/;px = $0.4\,kg$) 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 substap9m *39bkl e pw8/qzxfqq++brjzx); lnce 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 jcoc h i:wonbr4.rey:7o:z,+-W coffeepot to bring to a boil 0.75 L of water initialin jyb,e:rro4ocz :+c h:o7 w.ly 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 co520x)fuvn/o e; v pzofntent of 75 g of candy 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 2z e0pvo vo)/x n5;fufwater 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 at7-xuph) owjfe8 v.s e1 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 sp*i uu;/6.gnvjae mz4dxuad 71ommp ,;eed 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 the amount of heat:pw qe-8 )xs)tz/ qxhs needed to raise its temperature b w-)h:z 8pts)xqx/qsey 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 d,oyc+;yr8d fz5 b,cp16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high buildm y imo3-rgb(z:y)eg4 ing. If 65y mbog:4g-( i em)z3ry% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 18 l).cv vdv h48ot+7+devuftr 80 kcal of heat in 30 min by evaporation of water from the skin. 4)dvv8 vl ec+od. htfr+vu78tHow 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 - d g-wq/oa7sqan insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and h- qa-wq/d7sogas a latent heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the freezeu88 nlvpg6o5h jel/w- r 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 1.71p rq(km4 n olny(y m p)1xy2la/vfr8$^{\circ} C$. 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.y33sgeqtvr4s5z8p7, dyrwlmr 1 zt ;+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? qdwpls yrs 48r ev;zt57 +g,tzym331r (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 100a0zg cx iv-9oa.l)o9z $^{\circ} C$ 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 is :mlynq,4t(+exz )vbd u)b tj4 $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 at 9byn d/ymhm,ub :st . b2j1/d ny89ioe$250\,m/s$ 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 movi4v7zb)wns cf,xl .f0zng 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 d,gq6weqy. mbjrpw-i7 - kg40ly *ld ,8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impacw-i7q ewgp lrqd-,k06*gylb.m,jy4d t. 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 rlazw5i22 u8bwqnc9w 5 ku lv8 l,e.s3bod 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 f96x j5h bc :0xxj:bsidlow by conduction in Example 14–10, assuming that there are xbj0 cbshx:x :j6id 95strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissp)zz(epvxr3i.p xf8 *l *)vycivity $e\,=\,0.35$) 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 conductio2f7hhapf-2 3g gv y5mjn from the blood capillaries beneath t2ahm3 hyfg p7gj 5-v2fhe 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, sharec x7nnrdr): d, a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the airnrr ,7n c:dx)d 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 d xjzokk *: c7d ip2gh:2*umh (1uyr1x0$^{\circ} C$ 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 e7fhb -oyk,o 3 cwtk3q+jwtx5l*c:d7 same length and cross-sectional area are attached end to enk lxk5o -ofw3w7tc:3+hdby7e*q j,t cd (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constan wh 1701+lk bux)b)g3fd jwokbt, estimate the rate at which the whole Earth receives ened7f1bku bl wwb0k+go1x j3h))rgy 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 95xwd2 ye3*w w9p)oss v1 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 diffw dwv *yeo2w)xsp193s erence in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly f-zqute* 61i wrrom a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the total rate of heat loss tqr 6e* tziuw-1hrough 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 tw i:mybt ntvmc0k 2(3r5 7ilwt5o panes of glass separated by an air space, Fig. 14–20. (a) Show that tny: 05wktvm (im7 5i3 tlcrtb2he 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 11.0 kg of ice askga1,m -v 7xat 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.i.j(,;b qm odj1fdd+ s20 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 enib96sp(4uyd cu o97 pxergy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each 9xdi 6ps(4y7uo u9 cbpside, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is r7 jvcrd1t 5l52t,ntktested by firing 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 system has a temptdrr5 5,1cktlnt7 j2verature rise measured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total powerro x84tnhcbo sr/(w1+ radiated into space by the Sun, assuming it to be a perfect emiwr x8c4(t+h b1rs/oontter 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 peda( j-/k 2 0mpcpfutgvqov.;)rson 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 boulde:/q) j odzeqyxw,8;n xxyrp5,r rolls off the top of a cliff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of qpxo ny) , /:d;zjx weqx58r,ythe heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2m ;s 6vy5qkgd(.5-L insulated pail of water initially at 20.d(kv; sy6gq5m 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 djnsjs;cb7r6 q6 or0g -own jacket 3.5 cm thick with total surface arejgsjsn 0 6qbr;c-6ro 7a $1.2\,m^2$ 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 r9t+w- ajlp , 8r0sk)jo(.y nfxg(s mtjate 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 (x0g rnvmd8h u m,w3*pbe conducted from the interior of the body to the surface. Assume that the vn h8w3(x ,mmg0rd*puthickness 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 conductivityq2 fort4h/igg - 9exda9ehx* * of air) and area iae* hxd/* g9-qh gfxrot9e42$410\,m^2$ 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 travelin4hi*3ljx ,b atr *,dqng 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 Pr/(w9gqd fx aw x agg0*:9uhfg-oblem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporaa /ggf(u9g0g-*9:wx w a qxdfhted) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite me6/. czs1ro9 tfndqxy/ lts when it enters the Earth’s atmosphere. If its initial temperature wa69doxc/zs r1ftn/q.ys -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 crust increas:wbdup 6a5anqlp+(g7es 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– 6z;lk gnsgn l),a 8,(3wabnoi22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration al38gw)6b n(n la,;ganosizk ,nd 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 equalh8qm y9/brm(+:*yv jk n5 sqaf 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 and .*o py wv/is:abm*30y 6 ifdqdradiation at a ratp6i3s*q* byd mvyad0wf./oi :e of about 200 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 dishwashing6u zm xnint8a 61dir8,, there is “no hot water” left in the 50-gal (185-L) r i 1x6n8z anut8im6,dwater 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 6( 3lt f.if4 l-)l-ywzpuw-wp 4:kjloc0-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.    $^{\circ} C$