What happens to the work done when a gv+ dj2dlxoc vn10 e5ep6ba*p(o,e7k e3a(aejar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flo t j+jq0b0kwila,vqn 4i,lb 16w between them? Are the temperaturj,i 416v bba,q n0w0iq+j tklle changes of the two objects equal?

(a) If two objects of different temp xa/hk8 bin.u7eratures are placed 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 objects are th78na hu/ikb x.e same? Explain.

In warm regions where gx3+*6d7zn by kvlm:, qncxr+ tropical plants 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 qxdb*r+g cn k6y,+vx: 3l7nzm watering them in the evening. Explain.

The specific heat of water is qui5tjm qu/2np fa:vi6l( te large. Explain why this fact makes water particularly good for heating systems (that isjvti 6/u pm:2n5 lafq(, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sur-;qa t dsi)bq)rounding the canteen is k-; stbiq)aq)dept moist?

Explain why burns caused by steam on the skin are often m2v1x9 (kahuht3hg-gw6zu dgbm oxz (-z k*; ;iore severe than burns caused by water i 3vtahw- k-zz*2 (hx xugu9o;gb1mzdg(hk;6at 100 $^{\circ} C$ .

Explain why water cools (its temperaturq(c of4h du+(re drops) when it evaporates, using the concepts of latenq+c do(4(f hrut heat and internal energy.

Will potatoes cook faster if the water is boiling faster? c,0fpzmu qmg23u v aj8nf5-i/

Does an ordinary electric fan cool the air? Why or why not? If no8pflmp-;/ nqkt, why use it?

Very high in the Earth’s 7jxl6 oz-) vuyatmosphere, 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 surviv 81dvjmmn so p* kr;mh)7q8q1ved by covering themselves with snow. Why w d8jrm1)hmpm8n*17vo;sv qk qould they do that?

Why is wet sand at the beach cooler to wun,c0elhaj kh/2+j(yzy /l6:zt jlu(alk on than dry sand?

If you hear that an object has “high heat content,” does that mean tha/rq kvckjb+;50gy pa*t its temperature is high?r0ga b5jyv/k+kp * c;q Explain.

When hot-air furnaces are used to heat a house, why is it important that there uhqwm f,yu:+;,7 bgmxbe a vent for air to return to the furnace? What happens if t:qug mfh7+ u,x mw;,ybhis vent is blocked by a bookcase?

Ceiling fans are sometimes revez zddx y2:dr:56iw x:orsible, so that they drive the air down in one season and pull it up in another season. Which way should you set the fan 5d2:y:xixr6dw ozd: zfor summer? For winter?

Down sleeping bags and parkas are often specified as so2d4gk+me61b)2 vben zv0ds mlf6 z rkkx.bi :8 many inches or centimeters of loft, the actual thickness of the garment wheds8+kgdv6lmz1b 22z m6r i.:k kexbb0 f4vne)n it is fluffed up. Explain.

Microprocessor chips have a “wmqp2p k,u 5,mheat sink” glued on top that looks like a series of fin2pm kp5,qwu ,ms. Why is it shaped like that?

Sea breezes are often encount1gpjxf:ohm- l6g9h* ,t1zydf)j:ay sered on sunny 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 1:-*h sa 6, zxgpmy:)1jjty h9lgfodfof the nearby water.

The floor of a house on a foundation under wp)s a*bbg qy+kj1kk6k30ij2a hich the air can flow is often cooler than a floor that rests directly on the ground (such as b*g6)2a0s kpj 3+a1ykkb kqij 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 always taken wihzrr:z2/ak )niinj y;czq( lm(jd+ 4 4th the thermometer in the(z4qzlhzk )+acinj2rn 4i;d m:y/jr ( shade.

A premature baby in an incubator can be dangerously cooled even when the1 iig;xb7kel1xt r)d2e c 8y7l air temperature in the incubator is warm. yx1x1b8;rig el7dli)k2 tc7e Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why j9mjbe/ ujm g.+mqu;9n85d rldoes it have a vacuum between its tw9u+rmn.;5mjd/jg9l 8 jmeb uq o walls?

Imagine you have a wall that is very well insulated — it has a very highnr* yvn lx(46h/7vwfwvxos-3 thermal resistahr-ov34lnv(/y fw6*wnv7s xx nce, $R_1$ 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) ventil* qb4t8whdl/y ation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losseyq8/h*l4 bdt ws? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a piegc;,hm5gcm61lxi / k cce of shiny metal. Yetx ,/c lci51gmck;6 hmg the wood feels less hot than the metal when you pick it up. Explain.

The Earth cools off ad1m+;v83k ubzi+fxkzt night much more quickly when the weather is clear than when c8kxu v +;iz+ bm31fzdkloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastly(0xf u(m2dn ic foil. Explain how it can help to keep an immobile(mu fd2lx0y n( person warm.

Explain why cities situated by gnqyyn86h e-+the ocean tend to have less extreme temperatures than inland e-ynnq 6ygh8+cities at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0 kg of wh( fp)+*w gtc p ,.2rn ppy9lxjd-fo3water dwyc fpf,rhpt ).po p29g( w-l+nx*3 jfrom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will vs qjr:)cfv6/ j 81j-ya2bz re7700 J of heat raise 3.0 kg of water that is initially at 10 21v /-:z secf8)rr6bjv yjaqj.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person con53wvtj2;a zwa-rsuhl)metn nw7o 77sa8+ e7rsumes 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 of heat in the British system of units. Ofwe s74 b gv/l:4;ljtmne lmb:ls;f /7weg4v4t jBtu 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 ) uk4gkxv hc9x:*; rbty2n8yl$32,000\,kJ/h$ 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; p4ldkd 8ev(b jbze2w h;.-av 350 W. Estimate how long it will take to heat a cup of soup (ask2 bbzeldpvva4;w(.hjd;8e- sume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are uszn*goaoi,v0f a w25 eu/rmx;3 ed to bring a 1200-kg car to re*;i5vnxo,wu o/z egr3 f 02aamst from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it *.sfg -nv6 +/dm gbyanabsorb if its temperature rises fr* nfv snbagdm-/.+ gy6om 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substanh59 y fkmumck 5y(1zi8ce if 135 kJ of heat is needed to raismui8(m yzkf1 5k5chy9 e 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, ac 4rhwio3 8z/ /ll qfzkm81)- derxt2lnd water experience the same temperature rise when they absorb the same amount of heat. What is the ratio of their masses? [Hint: See T)-dl8x 1e/3k or/ t2fw 8rzqm4hl ilzcable 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer rrn mz.8j l7-e7a+ g -vmws; qhwm9rf-aeads 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 24t,/ilz.cd0gh 5-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 (mass ib78oaye r))e t*fc.ioy ,tc, = $0.4\,kg$) 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 to 3l k95h+.wbtg8 ,xenpc 30$^{\circ} C$ 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 bof8,4n c.y; dqmltz ae,9rp d6mil 0.75 L of water initia8pd9fd6qnmt,, 4; .zercyma llly at 8.0$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content ofa+:;1d j 096nyi/ jzdg 9l uncanl-hts 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 unll/dgdj-ca6h91yi0 ;n9z:s t a+ jnand 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 ,uf5-:ya(mmee i( mvviron 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 speeds) usxf d48h3y 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 neededtbko72svpfhv- . :m.pryk 0 6i to raise its temperature rpksk.0 v: 72vhi.po6f by-t mby 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 that isa ih xv*nn1ao/hmmd3j -5 lm *aj8a+. .uxtt9q initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped frot/andxe.4nn e4l9r. n13 zjwt m the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what xn. el n49.j zrt 4/n1nda3ewtis its temperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal ovxzrbx9x5 h m.qd ,./cd*3e mlf heat in 30 min by evaporation of water from the skin.xmq l,3d c5.xmrv9* /xebhdz. 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 1 r,3o )2lmucqae 9q *bjw6rcj6 qro:lmelting point is dropped into an insulated container of liquid nitrogen. How much nitrog a9olqrj ecq3q *r):mrl , cb16j2u6owen evaporates if it is at its boiling point of 77 K and has 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 freezer at -8.5vwi6nac6z .a.g+frkt2 mzp;+ kn/f ;t $^{\circ} C$ 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 wa,6xekwuae0 l/ter at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consumes 8.0 L of water over wr,o3gwz )hb5the span of four hours. Making the approximation thatw5,ogrbzh 3)w 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 at jw10 4+-.ksw vjs ;prb9s qo rksaz.q+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 mercuryn+s roy135j.;lp j dtc 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 atm )n*-nj: j7rix6,,bvtogpzv $250\,m/s$ 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-skater1gg6ekqf8 cteh vm837 moving 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 thdms /n,ot7wts /o1ab,gsx/;t e u.6hse 8.2-g lead bullet that was stopped in a doorfg7 / ;sdts/sbn,o6amhext,u /w1s.o trame 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 diameitw.v x-a q ;vkc9ny:/ter 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 Examplyc3m* u7 )zh1fh8lcrv e 14–10, assuming that there are strong gushr1uzf37hvmy8 c* ) clty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivit(ry2n)yaelt nfxusc2 u4*)1(tm f/u.ui)sihy $e\,=\,0.35$) 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 the bloc-iim/c 5iv)vw*kl2ww *l 7blod capillaries beneath the skin to -i bi2v *wil*/ c)cw5lmw7lkv 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, share a 12-cm-thick bricklked wu gv6j+q;4o -m1 wall. Because odgou j kql- w4em+;1v6f a number of 100-W lightbulbs in one room, the air is at 30$^{\circ} C$, while in the other room it is at 10$^{\circ}C $. How many of the 100-W bulbs are needed to maintain the temperature difference across the wall?    bulbs

  How long does it take the Sun to 7)kqdq (vio 7zf,bc :nmelt 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 of the same length and cri)1f fikb bw /c(gaa81oss-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a ig) c 1afbw1i8akf/b( constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the rate at which the whole Earth red ur ee/o:+pea(ky5/- tcd zm5ceives energy fr+/y:ez (u co5/a5 kt-edpredmom 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, ysq/u d;x**lkwhich is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the/*q ;x*ys uldk 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 mainly from a 4ak-x*ep,d x y5te19io.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19.ki5*ax d9 yoe-,e1p tx 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 gl u 1q ebm1qzlf(.e btq *1r6lnzbb;f19ass separated by an air space, Fig. 14–20. (a) Show that the rate of heatqb19 rl;bm lneb1.ez 16 z*(t1ffq uqb 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 dw.5k/srokt- 5ko.p y6:jnmjkg 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.+.m ;w hj;wehjr h-a-w20 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 en .a0k8k x6hlbwergy is contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, ix klabkw806 h.s 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 u(ckz7op+.3tgy/abd ckv4-kk g n3j:block of wood with a mass of 1.05 kg. The block and imbedded bullet togethek-k y4jkvt.pgg:bud 3on3(7a/+zc kcr 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, asshxxwgm, w w*w.y4 .u0ouming it to be a perfect ehwwm0g wy*wx4,.x.u omitter 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- jqh juey7 b/./kn2k7rkg person may generate $200kcal/h$ Assuming that 20% of this goes into useful work and the other 80% is converted to heat, calculate the temperature rise of the body after 1.00 h if none of this heat were transferred to the environment.    $C^{\circ} $

  A 340-kg marble boulder rolls off the top of a cliff ano+l+s; scf.9qp80 lu asvk,4q d*bc hpd falls a vertical height of 140 m before striking the ground. Estimate the t+*a c8hp k,v4scqpulsd bf9 ;q.o0+lsemperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropperbz po; yaelz(egr63.5x z9w 1d into a 2.5-L insulated pail of water initially at 20.0oe5 gz9zp xbe(ywl31. rr ;az6$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thick with total sw*ze qd:2uepg s(* ly1urface arelg(2**yp es:uw ed 1zqa $1.2\,m^2$ 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 aux dtj0)h ta/o(yio+2 verage 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 the interior of the bl4eplt+s qc37 ;q5yozody to the su7l53cqsq+;e tpl o4 yzrface. 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 ofav rn)y.7y1m rs70jua air) and amuy0san1vr y) aj7r7.rea $410\,m^2$ 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 atkck zlk58 lsm8v;swr.r4bi( pt(a zz,( vp:9z $220\,m/s$ 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 Pro2 s4.x3 jdfv/yk mozw)blem 58, take into account radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a temperature of 3vzo4.jf3ksw/m d)x2y 5$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s am(k vxdx52qntokmm3 h:.7 g .utmosphere. If its initial temperature km h3(koqxm.dmxv 7 2n5:.g utwas -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 incren,.e8:-(ahxjni k c jrf7 jpi9ases 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 r0j yt52nbjl e 1-dn.qhubber ball at a wall until they are about to drop due to dehydration an51d tq2en0h n-jly .bjd 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 finaln y3w. d6tgz-l result when equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a persou8;yr omd yqg:nkat1 7syn )39n can lose heat by conduction and radiation at a rate of a9k):dru ta73n8q1g;n sm oyyybout 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 (w1 mk1q8j sme g:v3 zxhjv3+jdishwashing, there is “no hot water” left in the 50-gal (185-L) water heater. :1(mxjwkq mj v 13 +gves3h8jzThis 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 lightbulb is 6igln(6,u jc , ciz4t3k5$^{\circ} C$ 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.    $^{\circ} C$