What happens to the woc7fd o1i8aq4 crk done when a jar of orange juice is vigorously shaken?

When a hot object warms a cooleemx 8*xt(y g7er object, does temperature flow between them? Are the temperature changes of the twoetyex7gm*x( 8 objects equal?

(a) If two objects of different temperatures are placed in contact, will heap)u vdk2zmu r,5f 8.vit 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 ifiu52u .mz vp8r )dk,vf the internal energies of the two objects are the same? Explain.

In warm regions where tropical plants q1s lbjz,/*rm pxw +v7w1bjo,grow but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering them in the eveninzlbqpjw rx jbw +o7m/, v1,*s1g. Explain.

The specific heat of water is quite large. Explain why this fp ;mf 2m:veq+0otg:znact makes water particularly good for heating systems (that ing2e:mf:t0q ;zm+v pos, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jackeoy8ozpkm .x6 au6;ot 5a.h k qn-nd;,ot surrounding the cant8m6kopxk yo5nt-da,.ao q ;o zun6h.; een is kept moist?

Explain why burns caused by steam on the skin are often more severe than burqz50.sx2 ehemoq i4i;ns caused b;2 0qs4qxioiz .5m heey water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, usingngf 3temgn2c68069/ka-h2 o1mws 3mcd a bbyb the concepts of latent heat ak s26 gnab1 9myce3 38gch m6n/bftmow-da2b0nd internal energy.

Will potatoes cook faster if1k:8(1tggo /ol v3ai psrf7 f3v/qq89vty gnl the water is boiling faster?

Does an ordinary electric fan bc e16/*c/ h ftno/vbicool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperature can be 728i41v7 : kv*dpmu zkzohp6t tzw7vb800 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed ns7 jpg3 ub2.hArctic expeditions have survived by covering themselves with snow. Why would they do that sj3 gpb27nh.u?

Why is wet sand at the beachvrf h:(+z uiu. ob2n/q cooler to walk on than dry sand?

If you hear that an object has “high heat contua c3rj;h)bx:7mj/ gs ent,” does that mean that its temperature is high?gjcabj :3;)r u m/7sxh Explain.

When hot-air furnaces are used to heat a house, why is it importu.x7-k vy .edr ;v-rju 0hp1btant that there be ak7-ryep0u ;v.u. dtj1-rxv hb vent for 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 d /*ylvd, ,bpvj)k0mh down in one season and pull it up in another season. Which way shd yp* , )v/bvh,d0lkjmould you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so manyt4c2jwhui yyvfh:t.* sr,d05 inches or centimeters of lofi5 2 .vhsdt ju4yy,*c: whr0tft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on towa j*ati c z0-lww4+*ijag-1q ma+b)t p that looks like a series of fins.-q -i ++wt z4 c )aajja0lg*a1btw*miw Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shm7*/5 a rodnivore of a large body of 7 dmiaov/5r*nwater. Explain in light 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 foundath t3 ,yics r8)ii3bjx2 8zgj2xion under which the air can flow is often cooler than a flooih2 ,r)sjxigy i3c 28tz x3jb8r 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 temperatb + y0:h97+ xin zyipmnyxw8g6ure readings are always taken with the thermometer in the shadeinym z bx:hyp9+wg +yi80x7n6.

A premature baby in an incubator can be dangerously coole1e06nm)* ucbj bhy hn-d even when the air temperature in the incun)jmc y - h*nb60beuh1bator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 15sie 275fspr u uw 4uic54pz2f4–15), and why does it have a vacuum between its two wallfp4s e4i zufw5cpu 7i552u2srs?

Imagine you have a wall that is very well insulated — i0 cvcok/ogk y;wx0c:xs/u 3su5m g 6:nt has a very high thermal resist /usmsn w;c:vogcoc6 50x: 3/gkxkuy0ance, $R_1$ 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 t x(c x9.md vejcm+g1+nhe following processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) ra x(c+mjegm. x dc9n1v+diation. (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 shiny metalzj86kj0,,1 h-vxar uyoix la(. Ya(kv1rox zyj6-haxu ,l8,ji0et the wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly when to,:nj hlfdr2a9p p)+l*xk 0cbhe weather is clear than whenf:+rpd l0nbloh k9 2)pjc *,xa cloudy. Why?

An “emergency blanket” is a0 6zyw9nsd l7 7jb 9mcfgp73 hqr70mwc thin shiny (metal coated) plastic foil. Explain how it can help to knlpwc07 wfmq3b9 7 g z7h6r9m c0ysjd7eep an immobile person warm.

Explain why cities situated by the ocean tend to have lecxa+ b7qkm .g*pk eman4 ,g55rss extreme temperatures than inq x5.g7 c,b n emm+kr*gkpa4a5land cities at the same latitude.

  How much heat (in joules) i 7lzpf8+cu5o us required to raise the temperature of 30.0 kg of water from 15 8up57+zcluo f $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat em5 v*ukjj k17a1,rv n:6utq.ky uo1 xraise 3.0 kg of water that is initially at:6 yjq*1ot.r vnk akj vue,51x7u m1ku 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 22b5zt8ey;jb )m e9/*)zpso :rx fmime500 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 heat in the British sysk paw l;ueq)(vz 1y6c2 s93wsatem of units. One Btu is defined as the heat n1aw) uy s;6( qawzsl3vpekc92eeded to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generaw1*yp2bvkuj 3o-k *y nh7ru-wte $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated at 350 W. Estimate how long it wiq qqqy/d6 -ddn)raq 2.0zmq-sll take to heat a cup of soup (assume this is 250 mL oqzy a-nqmqq)/0qd dqds2.r 6-f water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated3i) ;yaa2wv q*r 3eryw when the brakes are used to bring a 1200-kg car to rest from a speed ow3 i2eyvrar*3)wa;q y f $95\,km/h$ ?    kcal

  An automobile cooling system holds jgmp)etkw9nj8 d+0tum753x tp/d g - o16 L of water. How much heat does it absorb if itsne9w8dm tptgjmt 5-k xgupj /)do3+0 7 temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance ijtquvrw6nqxmz vrx9y0g/ -0x5y5 4 s.f 135 kJ of heat is needed to raise 5.1 kg of the .q0 t svyvu/- wrr4xjxny5xm60g 9 5qzmetal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same tl )zp0feuihob;t10a; ib ) )pxemperature rise when they absorb the same amount of heat. What is the ratio of their masses? [t0bo1;f;xpl a)z pih0)e u bi)Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads (lzl-3of.dt g 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 ( xuh-yu2u2h mutaerpf.26i5 temperature 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 (ma e qbfz f w:ctovdfn pkvs9r5-4z.,a*,n s0:7yss = $0.4\,kg$) 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 subknjhj 7yu,8yspl95)z stance 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 to bring to a boil 0.75 L of wa*h( /he.etvwx v -.vhqhyw0 rzs60h x(ter initially at 8.x st-evh0w( hxwyh*.v/h06.( vhqzre0$^{\circ}C$? 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 oy97s6drnowq63 b l7 xrf 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 0.727o 7rrnqd6by6lw9sx 35 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 irpo/)o0 pei9dlm6rik 5h1w -geon 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 o/92d:ev iyaftrqe);a 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 o z9n6svtebxfd1cnd9 / 1kh;,fbject is defined as the amount of heat needed to raise its temperature by hn6nk1b/ c;fzt9s9f exv,1dd1 $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 is initiad1ba ;+vzm ,z nut+h+dlly at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium spher+n f3hpj ,ci2pb:n4 fbe is dropped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the spher,fp2+ficbn 34b pnh:j e, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evaporat m9 6i2wd5;oex pgcg4sion of water from the skin. How much water has b6iedgoms w25pcxg 4;9een lost?    kg

  If $2.80 \times10^{ 5}J$ of energy is supplied to a flask of liquid oxygen at -183$^{\circ} C$ how much oxygen can evaporate?    kg

  A 30-g ice cube at its melting point is dropped into an insulated container of lvi *z6uco )k7diquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent hkv)7i*do c6zueat 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 tak )q+poua et45jen from the freezer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains 830 kg of water xqjxs sj* 0ec5ob..ij) bli/1at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consumes 8.0 L of water over the span of fo2+:3 jbyvdy y ae-hha(ur 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 r:-2ed3hj ab( a+y hyvyider 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 at 1 ,rg gr:byq-s)00$^{\circ} C$ 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 merzd0p p ,f+ mq.efn ,)mm(2yrbpetws-,cury 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 at ctl+z2c ,,sfreh:b 6 e$250\,m/s$ 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 d3 z ajbe6+j w3ku0tflm7:uw7moving 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 investig-co :jm+oe jejq 5(0vlator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fired at room jjj v-om:(lq 5eoe+c 0temperature (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 diame;t08rm lmvfp vj6 (dg7ter 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 Exampln sjh (jzr./g9rv a)r2e 14–10, assuming that there are strong gustyvn r).h sj9j2(g /rzra winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tun-io 7b,jay mov4)bp -l:p yje;gsten 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 skib tq,v y+rp 2;1fgimj.n. Suppose 200 W of heat flows by conduction from the blood capillaries beneath the skin to the body’s suf2mvr+bygi ,t;.j p q1rface 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-cm-thick /o.uhs6j1skfo u9(gekkq . j,brick wall. Because of a number of 100-W lightbulbs fe.,qs h gju91. o s(/kk6ojukin 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 b oe r/k m4kl3xsn+o6/3: aolxflock 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 of the same length and cross-sectiojhp cktfq9 1:1x zzq74nal area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperaq7fzjkp1t1:9zxh c q 4ture 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 v* p5kkre (s2+;is aykrek(k9 the whole Earth receives pe*k a(9 vskkk 2rkiye(;r 5+senergy 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 through a gtk:etjrk 88 pm 2zn;6 mv)npt6te* 5kulass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperkun*m6k tnvt tr jt6e8; 2pez)8kp5: mature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly ctj 7qu1-m,w0 )riyt3b: ij5iljrwa( 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 of heat loss through such a wall, if itjjl ta) uiqbcri yi310r5w7jt( ,m:-ws 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 sepak2bs eq)v d6e)rated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conduction i2 eb)dv s6q)eks 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 shojnryt,r+ p45vpm4ev) p+l/x b uld it take 11.0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains ax p7 lpdmqwszs.zm 59uqw8+m5kn8 6r.bout 0.20 kg of liquid at 5$^{\circ}C $. Drinking this liquid can actually consume some of the fat in the body, since energy is needed to warm the water to body temperature (37$^{\circ} C$). How many food Calories should the drink have so that it is in perfect balance with the heat needed to warm the liquid?    C

  If coal gives off $30\,MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $ 2.0\times10^{5 }\,MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of how much thermal enero0 );q l/ivtzfgy is contained in the world’s oceans, estimate the heat liberated when a cube of vtl) zo0/; fiqocean 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 zxb3 p2 aw+t9xa 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 temperature rise measured as 0 bxz2p93 +xtaw.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated ic t+.x(wpoke+p.d6qh+3q* znqd3vu w mql0r*nto space by the Sun, assuming it to be a perfectleuxq+rz. (t.poc3np*q+wq *0hdv k dmq 63+w 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 peqm0n/lpgyuk4- * dc1p hy,snstjc 2+)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 boulder rolls off the top of a clitt9 6 - gjt9-ujtvm )yuv1ntj(ff and falls a vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of jt-uy6gt nj9tvv 19m(t )tju-the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is drouky5s q uy86k+*(jm hwpped into a 2.5-L insulated pail of water initially at 20.0y wys* u65 m8(qkujh+k$^{\circ} C$. 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 wears3e(5jf6dn qtl w9kr-k a goose down jacket 3.5 cm thick with total surface area dk tn(9q-w5kj36lf re$1.2\,m^2$ 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 avere 1ep /66vkr(itj3haenlg1:hage 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 conducted from the76+(oktiy rd s interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that 6(i+oyr kds7t 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 (assumczwjm(9-/jef 4+db c- *tbombe conductivity of air) and a9e4o*j/b mjt(d-- mc cfz +bbwrea $410\,m^2$ 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 trjyfg i xhc.7swva 40qy(3f0r6 aveling 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 rz..: kzpyfr:* e x+u r2onuke:41md pfadiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hofmporf .u14+re:pue ky:zx kzn.2d: *ur to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enuh omca 2j f3pr3b+.1)pc8asj ters the Earth’s atmosphere. If its initial temperatmhj+pc32bfa8op.j 1 s3) uracure 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 crust increases :umg c -k;pg ys3;9ivrabout 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 squ(dqq750wl05 p-w ewqj5ip2v bufok ; eash (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall at a veeouw-;eqpl w5d 2pqjviwf(b 5 k705q0locity 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 wh 7d4,6( - bupi*gpfssjzo0pzpen equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a perf04zb(lg +m- kt(f vmnson can lose heat by conduction and radiation at a rate of about 200 W. Estimate how long it would fln4f(-0bm m(zv+ t kgtake 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 the 50-gal (n0/pb)xa p yemvz.y m8k v89p,185-L) water heater. This suggests thatyy9/e0 pbka,p)mnm vp 88vz .x 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 light/i- , y.lo/b fhuy3cmpbulb 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.    $^{\circ} C$