What happens to the work done when a jar of ormb f754oecrek8 k3(twange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between t2 otoa(ny8n2huke)dj)x)+ he+e e t k+hem? Are o)2e8)xu t+n atn+oe he2hy(jd)e+ kkthe temperature changes of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will *;fwmd/aojj3 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 internafd w/o;*m3 jjal energies of the two objects are the same? Explain.

In warm regions where tropical plants grow but the temperatdix8itq)ap- 5ure may drop below freezing a few times in the winter, the destruction of sensitive plants due to freezing can be reduced by watering the)xti-8pqi a d5m in the evening. Explain.

The specific heat of water is quite large. Explain why thin-e 7cm(zh 85b s;w,icz n2ncss fact makes water particularly good for heating systems (that is, 7 z2nw8sizsmbh;cn,5c (en- chot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surrounding th,qld9yb iwd2*gk4p;sd+gv z 9e canteen ikd wdzq9;b9s 2l gd+4,*vgi pys kept moist?

Explain why burns caused by steam on the skin are often more severe than burns43o ih hn 133kqcqlxz7 caused by water at 100qcq3l7h oznixk1h334 $^{\circ} C$ .

Explain why water cools (its temperature drops) wqx2 q+j it+ct)hen it evaporates, using the concept+cxti jq) t2q+s of latent heat and internal energy.

Will potatoes cook faster if the water is boiling fasfa-8i-zy-ms/tyq m c1 ter?

Does an ordinary electric fggnvzb;ed6b n.9v i s 2n(g09san cool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temp fgn2b (dnni7yv *g-w4erature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have suq:+qt 4.h e*v mfjh3;dwve*e +pgu(zyrvived by covering themselves with snow. Why would theyw4*uhgj mq+h+*( 3ypt:;eezqe.d v fv do that?

Why is wet sand at the beach cooler to wti 2(y7sjh(xn im415sn v ;wc nj2fb)falk on than dry sand?

If you hear that an objecv2q( mj0 sxtsjn 7+xe(t has “high heat content,” does that mean that its temperatejsq( t(70x j+2x mnsvure is high? Explain.

When hot-air furnaces are used to heat a house, whm q;ru(d* xtgz+t.w m*y is it important that there be a mtgtu+;(r .xqwz** dm vent for air to return to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible,whx x74 b)i/5h -v9fnwe.wpas so that they drive the air down in one season and pull it up in another season. Which way should you sephax-f7e 59n /ws )4hiwwb .vxt the fan for summer? For winter?

Down sleeping bags and parkas are often specified as sh4zvkk-yz,(5fvln0 zo many inches or centimeters of loft, the actual thickness of the garmeyzf z4 nv v-(0zk5k,lhnt when it is fluffed up. Explain.

Microprocessor chips;ijundmpxhd; / (1 pi0 have a “heat sink” glued on top that looks like a series of fins. Why is it shaped lik/upm;pxj;01i hnd(di e that?

Sea breezes are ofteny*j i(1/arc(h z2ncni encountered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperatureicra*yizc2h1 ( /j( nn of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the ai.og7t* kme p,38h 5dd vy3mrfir can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foundatioim eo vf8hpryk 5t,33dgmd *7.n). Explain.

A 22 $^{\circ} C$ day is warm, while a swimming pool at $22\; ^{\circ}C$ feels cool. Why?

Explain why air temperatuzu 43 x,7c-afi ;odjkrre readings are always taken with the thermometer in the shaddx jf -k r7oc4,;ua3zie.

A premature baby in an incubator can be dangerously cooled even when the airy60pt jh yw/ 9fgffg 3,pk9xq7 temperature in the incubator is warm. Exk,ft gjhqpgpwy6f f37xy09/9 plain.

Why is the liner of a thermos bottle silvered (Fig. 14–15)*4 xsz5 f:va5r4zco4g2o xqvn, and why does it have a vacuzqo2zna5fg5 x44v4cv* s: xorum between its two walls?

Imagine you have a wall that is very well insulated — it j7 : sq/z86lc ok6.vzv nmav/lhas a very high thermal resistana6lvk8 vmnz6jqsz. c/: 7/lvoce, $R_1$ 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: (1foj a9x c9z- 3es.g*cx) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): 3cexo*j9 f9zxac.-gsconduction, 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 piece1s,s 00 fzgrzluc:o7mx7 zcc- of shiny metal. Yet the wood feels less hot than tx1: urcf 7zc-7zsc0,og0zlm s he metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the d)dwaj y; 6u+ -be1 8albuacxucy 84du-e*r0 oweather is clear than when clo4-8oa a8ed; d+c weybualuuy1)bd* rjx6u0 -cudy. Why?

An “emergency blanket” is a thin svwstl/. u,8za hiny (metal coated) plastic foil. Explain how it can help to keep an imw 8ltv.auzs,/ mobile person warm.

Explain why cities situated by the ocwp ,* bm-8n p u6ur jaxfdse(f(-c(bh8ean tend to have less extreme temperatures than inland cities at the sa fpb-8p f (br,hjxms8an*6w -ud u(c(eme latitude.

  How much heat (in joules) is required to r.p/m rnf mvn:-aise the temperature of 30.0 kg of water from 1r mn.: m-/pfnv5 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is initiallgmtc,1g2kt+b*g)d akn 9bxgol8 97y hh (.bkxy at 10.0gxl.,9abm7x(* 1gytg2h+kn8h c )bkbogt 9 kd $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cgfl5g.eb p a3om4)0np(xo.r 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. uj 8ndcpk cfj7u711mur6 f33qOne Btu is defined as the heat m qf fkc7d78 13ujnpuj uc61r3needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate ,a+fn+zggcs; $32,000\,kJ/h$ 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 will tah.okvuu 3;, tuke to heat a cup of soup (assume this is 250u;h ,3kuoutv. mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are it38;dz ihb-zzvhtd94rta9a) 3 o l4iused to bring a 1200-kg car to dt4 -oh r9z)b;dzvaia439h 38zi ttlirest from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it absorbmkgzdrt ;lys*-rb,al*f .k gl db5q ,n2:p6l+ if its temperatumk+q5t* - 2g f*.6r;yzrlablg llkn,sp:, db dre rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ vjta+r(,m/2kxl q:028ab eoi co 3pjg of heat is needed to raisvp/ blr 02t:j, x qkjoo(+8ieag c3a2me 5.1 kg of the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, alumj1 cry)-0u/,r zji9qn*gy,g kc 7dmwf inum, and water experience the same temperature rise when they absorb the same amount of heat. What is the /,wq91rzmgk,fry7gj0-c j) y ndi u*c ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer readsqsc*(csjpo n)+ ihcm2 x 1pd:6 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 tempmh o ui-ie8.t uqk cf1,;+w:fva6or5werature 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 ( xm:7ws r.n0c pnk ),7,e4nqnon:eetdmass = $0.4\,kg$) 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 ji;).mtf/ uur330$^{\circ} C$ 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 brinsco m*9 e dp;7cgl o:x3)l8zjvg to a boil 0.75 L of water initiallydlco79;gxpo3l)e j vzmcs*: 8 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 of 75 g of candy from hv+*x+zmb5ji*q 1 jvdthe following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water c+zh*dxv 5jvm+iq*bj 1 ontained 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 iron8tlbb( -+ cy8wiqh)fd 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 hammny9)v zi+9vhaa j(k)3 s)q)tyks9lv ker has 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 object is defined as the rkjfel7d j1 /(km.q gl,lq8/ramount of heat needed to ra//m(781gelrrdj, lqkj k. lq fise its temperature by 1 $C^{\circ} $ . Thus, to raise the temperature by $\Delta\,T$ requires heat Q given by
$Q\,=\,C\,\Delta T$
(a) Write the heat capacity C in terms of the specific heat, c, of the material.
(b) What is the heat capacity of 1.0 kg of water?    $ \times10^{3 }\,J/C^{\circ}$
(c) Of 25 kg of water?   $ \times10^{ 5}\,J/C^{\circ}$

  How much heat is needed to melr vptko,8*.xb-i gl1o.f/ xnlt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere if53p,kx7pvy6 hj; k nxs dropped from the roof of a 45-m-high building. If 65% of the thermal energy pr7hyj5k, kp36fx; p vnxoduced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may givev c 2v(w(xebe-t( 6kzr off 180 kcal of heat in 30 min by evaporation of water from the skin. How(bkew2c- tx(ve (z 6vr 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 i x7ymw u* i9,p h1.0iqf6h,kkw3nhvb tyyii86s dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling ymi x7bi *ih61, q8huy0kw.fny69khw3ip t v,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 thgu8le3p; jt,le 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 r*x3jnjdq9 yhl; ; e)iof 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 consumes 8.0 L of 733lhzfce,x e water over the span of four hours. Making the approximation that all of the cyclist’s energy goes into evaporatingfe xch73zl,3 e 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 100jdu;(ti) -llo $^{\circ} C$ 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 mer84 j k6+uvp (uayo0jqscury 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 traveli;m1gy m/4 g53aq.qpfjj( rui ing at $250\,m/s$ penetrates a block of ice at 0$^{\circ} C$ and comes to rest within the ice. Assuming that the temperature of the bullet doesn’t change appreciably, how much ice is melted as a result of the collision?   g

  A 54.0-kg ice-skaterv0g -w1xa lt5+;owy ft 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 t,vdq6/otdl2nz/ 6uj. 6 smhc phe 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fnps6 dtq.z6o/jm cv ,hd2u6/lired 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-lonq (.cz reiog48g aluminum rod with a diameter of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduction in Example 14–10, assup)5o/ov gd m)g)temv:ming that there are strong gusty wino gdo:)5 me/)pvmv tg)ds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten p0r3x0 -q7ch ua g1stnsphere (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 h k cpns59q3;ooo7b g6-9tqmz eeat flows by conduction from the blood capillaries beneath the skinqtonepgzsmob6 -399 5 okqc ;7 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, share a 12-cm-thick brick wall. Because 1 1gfzos-2hj*k 9dytfof a number of 100-W gfjy k9sd1*h 2t1-zoflightbulbs 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 melt a block ociy:yg+ixvcwr : ukycw(w;9/qamd )d m6 )k*1 f 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-secjr,jq1 g1)e +v+1 w)vhjcawvntional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace 1ve1)rvhjq, wjj n cg1w+a+)vmaintained 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 constant, estimate the rate at wh -9abs:zd kbqw:,hph b:jo (4uich the whole Earth receives energy fro4ujb:qo(9dw zpsb,h:k h :-a bm 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 iyn23 7kq g93t4k 2+ bvtkjpynos dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of t y 2k4bqgytk+2kjv9pnn37 3othe glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from /g,cz i8vtxm 167xzmm 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 its totalm6z8i7v 1x ztgx, m/cm 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 separated by an air space, Figxgsqpo(-yu ,3 n*2 fgv. 14–20. (a) s-(v u nopyxg*32 f,gqShow that 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 11.0 kg of ice at 0cu,6t nsv98zl$^{\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 about0 n3 tcg l49j0vm(jpxn 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 energy is contained in t.p vbjq0lk--n he world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate the oceanq.kb j 0lnpv-- water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed block of8 e08otf(*.xdsya9a5 by6 ym gs,txbf wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reachxfo b 6.tsdgyb a,e a9f*8msy0t5yx(8 ed, 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 spac*h dlymou +5m9t9 t;6sbl.hzne by the Sun, assuming it to be a perfect emih9blsdyh ml6*. t5 ;+umzont9tter 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 per,4n(gca) xov pson 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 rollf-k+c w y(juay0jt 85cv)ce;zko.z+ fa6tut/ s 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 the ttka a;zw8c.+ut-j6fcy /j5ez0) c vkou+f(yheat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is u/0mw+4y fzwidropped into a 2.5-L insulated pail of water initially at w4zmi/y+ uf w020.0$^{\circ} C$. 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 f8tl1n4c5 t9cn6kr /ncsdp b; a goose down jacket 3.5 cm thick with total surface arebt8tpn;cn/r k6 l nc4cs5f1d9a $1.2\,m^2$ 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 metabolis b1hv365m 3v7(;+vcufanae;uhb7.x gu uhn hlm 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 fr/ufa66rf/3lg ( lnwh m7 2 nqn(cnjc4tom the interior of the body to the surn 7n(ctlngf/wr m6 423(auhlj6qfc/n face. 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 w)xo9qou ,/9d:tqiefi alls 17.5 cm thick (assume conductivity of air) and ar fe9,o9qxdq:)ui o /itea $410\,m^2$ 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 at /8vy k1r(p h 6/xfby fnvo6s;b$220\,m/s$ 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) inj+a 0-/oorg, e w-hhlbz--fvt Problem 58, take into account radiation from the leaf t vjght r ,bo0f-eo-z a-l/+-hwo 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 when it enters the Earth’s atmosphere. If its initial tw kfh,m a35qwig2 (/qiemperatqaw wk2 fh3,qi/(5mg iure 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 ekyxl)wm,kt o3x9ln h: :,x3o Earth’s crust increases about 1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two people hit a soft rubber ball wonllj2bdu*2 t( (i8 dat a wall until they are about to drop due to dehydration and exhaustion. (2i jnldd* (2bu lot8wAssume 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 equal masses of icmqb eya5tsa nc2*7he:dc-6 *oe at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can loseou/kx4,n3nt9dx d 3q au41w hh heat by conduction and radiation at a ru n3w/qo dhxtx4ahu34n19dk ,ate 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 dishwashing, there is “no hr4: ci6u(+wcubjrk t7ot water” left in the 50-gal (185-L) water heater. This suggests that the tank hj4rccbk urwu6(ti+: 7 as 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-Wad pob15o7bd+ 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.    $^{\circ} C$