What happens to the work done when a jar of orange juice is v5ga lf tgy8vyb) o)kj+c.8/fcigorously shaken?

When a hot object warms a cooler object, does temperature fl6*skriywi (ib4 g xa82ow between them? Are the temperature changes ofy 2ia w(6irg8*kx s4ib the two objects equal?

(a) If two objects of differef v98ykcj-adi/a4arvtp4g/* j * 0hua nt temperatures are placed in contact, will heat naturally flow from the object with highervuf8 jt cha-p4 0dvy9g j4a/**iak/ar 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 the same? Explain.

In warm regions where tropical plabxy )4lehfj).-c 0n ionts grow but the temperature may drop below freezing a few times in the winter, the destruj)hbxc0 yl-.)if no4e ction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite c(mj8m e3nzkn5, wq5h large. Explain why this fact makes water particularly good fo hezkwj m,q(5c n538mnr heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket suz9h9 fzpx/nm* 4o7 ahcemd .*trrounding them.*9 4h axpm/9coz7t*zen dfh canteen is kept moist?

Explain why burns causd p:fi; kfzhv4v 9 l3x7v-jm-yed by steam on the skin are often more severe than burns ca4 ;fz lxk:-mi3pjd7fhvv9 -v yused by water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) whensg2rhl0*yz hfl0db4s; ztesld/vx; x0k3 s ;* it evaporates, using the condr* zs ;3; lf2 dkssxzl*e/gtsyh x04l;bv00 hcepts of latent heat and internal energy.

Will potatoes cook faster i9 (h hu*noh,cbf the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, whpcd6 :9zgjx3p y use it?

Very high in the Earth’s atmosphere, th9jwio8vn0:wgln z 7r5 e temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survivehzat 8u*q4nr 4d by covering themselves with snow. Why wounha*8 ut44q zrld they do that?

Why is wet sand at the beactw0uy wi5s t4,o/ mejrs u(j1;x:m s6jh cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does th:lnxd, yqfjv 1 y8hz;; w;x:qmat mean that its temperature is high? Explai8wq xz,y vhyfxl1d ;m nq::j;;n.

When hot-air furnaces are used to heat a af+.vcp46;l k h77kmbn- xjmmhouse, why is it important that there be a vent for air to return to the furnace? What happens if this vent is bl7 bm4lp6-nxm v7+acmkk f.jh;ocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air down in one y1)l+nft hq8 lseason and pull it up in another season. Which way should you set t tf8qy1l)+n hlhe fan for summer? For winter?

Down sleeping bags and pam5 oygcdrk j )47mvbjjnr aa;0m4 /4m2*vny*p rkas are often specified as so many inches or centimeters of loft, the actual thicknejmvjyv5 mcorj;) n*40a7b/n k2d a*rmg y4pm4ss of the garment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” gll f4x.tww67bh r+u4g vued on top that looks like a series of fi wbh wu rltg6fv47x+.4ns. Why is it shaped like that?

Sea breezes are often encountered on sunny days at the shore of a large bo9g1e s ttgr fgmy35+7jdy of water. Explain in light of the fact that the temperature of the land rises more rapidly grftgt+sme 937j15 y gthan that of the nearby water.

The floor of a house on a foundation under wtietj3,a)pn70j*yk. 4xg*iq iq rc n( hich the air can flow is often cooler than a flo4r tnnk , ) eiajcytj.*xqip 0qgi(3*7or 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 temperature readings are always-98ub 1wqasch *bq 9rr taken with the thermometer in the ra- 9rwuc*s9bq81 hbq shade.

A premature baby in an incubator can be dangerously cooled (nnqr7u5q3yu t4tk; oeven when the air temperature in the incubator is wa5;o( 7kqrtn 34nu utqyrm. Explain.

Why is the liner of a thermos bottle silveredpxs4 /2th9rph. o( ktpg-0y sj (Fig. 14–15), and why does it have a -p r4(t0pgk2so9sy t/h xp.h jvacuum between its two walls?

Imagine you have a wall that is very well insulated — it has a very high therv9t9:ru*g0oibz +opk0n y 7 knmal resistance, ztok invkn97b0+*pg:0o r9u y $R_1$ 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 tkm-dj . f;w-uf,kg 0lvkw/:qlation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. (a) For tm 0/jgq- lukw.kv;t-: d wkf,fhe 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 lyingqwe0ol/kvm i tzx++.11efw/r j m5 4mj in the Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less hot than thej1j zvm+lm/ /w.51e itf 4+kmrxoe0 wq metal when you pick it up. Explain.

The Earth cools off at night much more quickly when the weather is clear tha93 uy04kxlqv pn wh qkvl4u30px9y en cloudy. Why?

An “emergency blanket” is a(n2qikm8qu9cm d+ .ip thin shiny (metal coated) plastic foil. Explain how it can help t i.c n98piuk m2dqq(+mo keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme tempera.p la* 3w22mcyht65b n *th ld2orr;ahtures .loa** wr2thr hct5m 2yb h6d;3l ap2nthan inland cities at the same latitude.

  How much heat (in joules) is required cx205kw v5 0w3 *jeqo 7hnxoirto raise the temperature of 30.0 kg of wat*0hoc w7ne5x0iqov53 r xkjw 2er from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is )jr7(l 7zdgj6hida5b initially at 10 7)7d6 (jgri dzal5bhj.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Ca ppwu lh(u*s:;l 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 o:)tz rn, (p+al*pxpbu4rw(zk f heat in the British system of units. One Bt(up:,pw)rbk r lzz +tx*(np4a u 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 generatg0o .em neruyyyjb*ph5 ,hl3j+80+ j7dh8ek oe $32,000\,kJ/h$ 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 p ;kaxy9 x2 l+fh4p.phhow long it will take to heat a cup of soup (assume this is 250 mL of 4p .khh yxf92a+;pxplwater) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brake;4gyr*p 0 lvu pxu*x;es are used to bring a 1200-kg car to rest from a speeul0upx* *gxep; yv; r4d of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it ab1 llh/+cwj0wvhc h ;n2sorb if its tecw;h1/w l2lh0 hvn cj+mperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is needvnbb1kw 9xu68z n/+c (7mwu2 (hxlwlked to raise 7(nlbul2v/9 xchz1 x+wwnuk wkm68b(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, and water experienczqqc;ppl /;w8e- b tpy) t7-kie the same temperature rise when they absorb the same amount of heat. What is th k/z-;ybt7piwpl c;)qt p-e 8qe ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermome8sabgb lv: hs c xtvm0bu4:n;k:259kster 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 copp ggbv 0h;0 vw:4qjiqk9er 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 horseshoekiw5 lx jffp8ai3/-+k (mass = $0.4\,kg$) 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 p3/ fnr;rkr+usubstance 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 br(cma vq nt+h nd)z:5qie -xef6zo0qofi*9,;ming to a boil 0.75 L of water initially at 8 0detz*qchq(mminq 5+f9e x:vo n, ;)-a6fioz.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 the following measurements. 6 *ldsm/dh8 1g7pevlxq jdxsl1z7 )+gA 15-g sample of the candy is allowed to dry before putting it in a bomb calorime177l)xe* / 1+jg 6dzd hxvmsp8slqgdlter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixture is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iro/tv0y* it)u oac50xce n 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 ozkqljo2:gh (4om iog4/+ge) hammer 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 amount of heat n8 nrijz:zq cw*ftv+kk :aa, -.eeded to raise its temperature by 1 a qt wzza:.jfk,*:- nvir+ck8$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 initially3.h;u9yt5t rm+bopzumx 2oyd )y09wak/i y0m at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-hig1cp;f ry/u)fv h building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its tempf/cfuy p) v1;rerature increase?    $C^{\circ}$

  During exercise, a person may gn*sjtm5hn2)np f*;zz96 z3pxyrw qi* ive off 180 kcal of heat in 30 min by evaporation of 9z* q) p2**xsfntji hn3nwr 5my6;zpzwater from the skin. How much water has been lost?    kg

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

  A 30-g ice cube at its me )v chxg1il-2rlting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boiling point of 77 K and has a latent heat of vaporizaxh lci21v) rg-tion 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 8kk +wiu23i-bvf6.dax.w y nlen 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 contains5m /c 2a2fd jsmq0qdmx.8yohq6 z 8acyz;zs00 830 kg of water at 18$^{\circ} C$. A heater supplies energy at the rate of $52,000\,kJ/h$ How long does it take for the water
(a) to reach the boiling point,$\approx$    h (Round to one decimal place)
(b) to all have changed to steam?$\approx$    h (Round to the nearest integer)

  In a hot day’s race, a bicyclist consumes 8.0 L of water over the span of fot:xwnm6aj 4x fzd / 76v,lf 7lkq5z,xdur hours. Making the approximation that all of the cyclist’s energy goes into evaporating this water a5xtl/ mq kx:z7w7,ddjafl n646v,zf xs 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 atd0z2) - i3r,c ih2 ;ojlphj-djuq5u vo 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 u)gzwhu6, 1 hsmercury 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 travelin2u*h q2 zcxg*og 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-skaterpv*+d6 umb+ gm 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 investigaxv r:oc d q9x(9y zefe21 4*lm(;udsbxtor notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bul* bu 2 ((xx e 9dsyld:vz49;1ofcxmerqlet 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 diametehw dp2n*dt9m)bx0 :dvr of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduction in Example 14–10, assuming that l3i5+eb( punvthere are strong gusty winds andb (3 lv5npuie+ the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiatefx jyhf-i-a/,nry 8los /2 b yn;..plld by a tungsten sphere (emissivity $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat flows by conduction from the bloo+/yl9jrl)+n kzxhcz b50 )wp 2ezwa2 pd capc y22e+ l95 w) wr )b0+hlpnzzjx/akzpillaries beneath the 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, share a 12-cm-thickfc9 wms 1d4etzj)7 yt) brick wall. Because of a number of cdz4s7tetf y9)m)j1w100-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 melt a block of ice at fs)y(hq ax;6syjqy ) v1:ky96ucs2 ci 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 c.fvk wo1 1jj)aluminum rod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace mai wf)v 1okjc1.jntained 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 constanc b0w fp;pejg 0(6ev:dt, estimate the rate at which the whole Earth receivep j:wc0gdb0 pee;6 v(fs energy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 p h7a34ixw)zr )4rc;wwg awr5W of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What ir4xzwa4iw ;wga)r)rw53hc 7ps the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainly from a 4.06gk hv73y y1i.mw uc8q-in. layer of brick and an R-19 layer of insulation, uvi768w3gkq y ym 1ch.as shown in Fig. 14–19. 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 glass separated b2 ls+2a-f,alk/ :cn-m uo4vmw sde2xdy an air space, Fig. 14–20. (a) Show that the rate of heam+l- -/2a4ck ,wnsfu vx s o22:lddmaet 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 bq 9wvdd8j6v2-;ov nld fib) 1at 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 0.20 kg of lirkqn:n*cq55* wog8nuquid 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 conta)cc(wd1w 9 pr1n16;zh urwgcsjk4b: nined in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cool:1npz9wc dnb w 6hucgsj); k1rw(r14ced 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 v/ciu wg;h5j 98ft-fan 7,fsc,4t kj nfyr2.xit into a fixed block of wood with a mass of 1.05 kg. The block andfxc; y/rc ,tftk48f2 s5 u,gnainvfj97.w-hj imbedded bullet together 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 r/e)n dwplmh,u e q/z,5adiated into space by the Sun, assuming it to be a perfect emitter at edwp e/lqz) hun/ m5,,$T\,=\,5500K$ 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,h54z6.;da -binazpd z-sb5lfs 5mfdx t2xm 92 a 70-kg 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 and falls a vertical heu3u.sc6l 5 mbgrvh 73uight of 140 m before striking the ground. Estimate the temperature rise of the rock if 50% of the hr7v. u u33b5hlc6sugmeat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2s)-9 w/n :odzfy;k+gv9 sqgdj.5-L insulated pail of water initially at 20.0ydns)gw/gdos;+9v z 9q:jkf -$^{\circ} C$. 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 thic -k+j ioc*tkq;qozuu(amo3z)b/p m44 k with total surface area /o*i+ c4 z4 m tkkzauq(oj- b)o3upq;m$1.2\,m^2$ 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 ra;vi vrz(+mlhrnyhblr 5 4g4: .te 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 w+bc qw:fs8i d)hich heat can be conducted from the interior of the body to the sf:dwcb)8iqs+ urface. 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 conducr83ml vhkha7 g3(l et/tivity of air) and area/gtm l a7 lh(3hv3k8re $410\,m^2$ 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 trave6iw:8 5ac(d+ rx1fyf4b ,(w iktbqawiling 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, t14gp0mh+uo st4q cy 1hake into account radiation from the leaf to calculate how much water must1t4qhhpy4+s g0ocu 1m 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 initia, 24jqjrn;)3myz :y q2tgdnexl temperature waqjdj2 3m:y),n 4ye t;rzq ngx2s -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 about 1.*wz5d8 )kjh sl0 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 so7bv/dlzs4y z9 o wvuwme4c8 --ft rubber ball at a wall until they are about to drop due to dehydration and exhlzw/bc9so8dmz7e -4 v4-wyu v austion. 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 whedyg.18 2*jk e,i qesfun equal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a per:8z8lc;r:cff9) jzbrvmd5kj/ ;cso fson can lose heat by conduction and radiation at a rate of about 200 W.f8c: dfro;c98;rzcjlk vz/5 )f:jbs m 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 “n6q pg:tw il5- fooa3z m,ej/l8o hot water” left in the 50-gal (185-L) water heater. This suggestalf6p5wi,ojg 3/e:ot ml-z8qs 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 lightb;z p8kr89nn sfulb 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.    $^{\circ} C$