What happens to the work done when a jar of oranh m i.q7n.zz::x em-uvge juice is vigorously shaken?

When a hot object warms a cooler obje2n br. k h/aygub+5n,bct, does temperature flow between them? Are the temperature changes of the two objectsghn 2/+,k5 . uybbnabr equal?

(a) If two objects of different temperatures are placed in contact, w h1do-f0wz:a will heat naturally flow from the object with higher internal energy to the object with lower internal enezd-oh fwa1:0w rgy? (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 plants grow but the temperature 2m.i 55s 3jmab:m,qu-ybtzdw may drop below freezing a few times in the winter, the destruction of sensimjm b mq.b izawt -2d,s5y:3u5tive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is qujy v sq ak*zl:,d-oyibyf;tq +1. bq2.ite large. Explain why this fact makes water particularly good for heating systems (thfy* otbl.a2yjsd;i-1 qbk.:qq,y+ z vat is, hot-water radiators).

Why does water in a metal canteen stay cooler if the*o 2owjg 2vy7lez7tk 2 cloth jacket surrounding the cantozetv* wk o27yl27g2j een is kept moist?

Explain why burns caused by steyr5 9 t,e ympjh51awux w,h0 edns11.ria7*rv am on the skin are often more severe than burns caused by x e17r9*su5h,1hymawa jw 1 v50rtr. ineydp,water at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporates, using thek3+g)ytcpz v1 l.ywm3 concet+ p 13y3vw.)gklc mzypts of latent heat and internal energy.

Will potatoes cook faster if the water z ku/ebp;*lq3g 7x:9yw u fi2odea :+kis boiling faster?

Does an ordinary electric fan cool the air? W3zvy) b23z: lnf aeq.n ahbvf2zu/4k 4hy or why not? If not, why use it?

Very high in the Earth’s atmosphere,rpyhe5chxj69 rxvc7- 4wozq2)c9h-k 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 survived by covering themselv 9bz(i/tj 796w fv uczeclm(8(r;qkk+vnv bb9es with s ntwe79m(lbvq cb(kvuvj9c6fr9/zz i+b8k (;now. Why would they do that?

Why is wet sand at the 7f7zsc 1b4 ouqvbb6zjm9/ u/ rbeach cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mean that its tem+0p9 ko s7fpdqperature i0o+s7 k9pfpq ds high? Explain.

When hot-air furnaces are used to heat a house, why is it importiy5 brj l8g4u73qwe-k ant that there be a vent for air to return to the fu3bwk rql -e85iu7yj4grnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are someti m48asqn9mb pz *obc0(mes reversible, so that they drive the air down in one season and pull it up in84* q9pc m(asmnb0zbo another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified ago)z40q q 6q2mubw)tf s so many inches or centimeters of loft, the actual thickness of the garment when it is bgqf 6q 0m) zo4wq)t2ufluffed up. Explain.

Microprocessor chips have a “heat sink” glued on top)/6an l j+znprce5nc7d- 2fik that looks like a series of fins. Why )c/pn lid- j756a+zken r n2cfis it shaped like that?

Sea breezes are often encountered on sunny days at the shore of mnlou: .pqv 4dd l8;yyk;f//l a large body of water. Explain in light of the fact that the temperature of the lanpuld;:o dv4k/y y8qll;f/ mn.d rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which the air can flow is often coib9 a4em mvux1p xq 5o;:r+7zaoler than a floor that rests directly on the ground (such as a concrete slab foun+45uxoevm zi b : 1rma7ap;q9xdation). Explain.

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

Explain why air temperature readin)sthypa* f(ihr ;.s9 wgs are always taken with the thermometer in the shat; )spw9ra( yf.i*hhs de.

A premature baby in an incubator cas8+6b ju e ,k,imjue3an be dangerously cooled even when the air temperature in the ijj3,,kea i86seuu+b mncubator is warm. Explain.

Why is the liner of a thermos bottlet /uv7rw+t3)p dqf7k n silvered (Fig. 14–15), and why does it have a nft/ 37 p uwk)qd7r+tvvacuum between its two walls?

Imagine you have a wall that i meyum2mhv p qdfa03i5l,5 .)ks very well insulated — it has a very high thermal resistance, 53,lmk0m u)2hfipevm d y.5qa $R_1$ 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) ventilation ara 9fi8l2u- foo;cur cid0f-k/ound edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiation. 2ff0 -fu/ k- o9iracud;o8l ci(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 heuk;wdw8 p(6r uat than a piece of shiny metal. Yet the wood feels less hot than the metal w6wukdu 8w(p ;rhen you pick it up. Explain.

The Earth cools off at nig; j9wi hk g-tm+ns *odv)6x,gsht much more quickly when the weather is clear than when cloud tom-)w9g j;6,k*xs hnvsi+dg y. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Expl1-wkpoof :7/ ynuzna8ain how it can help to keep an immobile person 7 8kfo-zpw/u:1ny oanwarm.

Explain why cities situated by the ocean tel1l3ci f lxe ksb.7lbx+/v *4 t.ifv2dnd to have less extreme temperatures than inland cities at the same latil1v 32.xxv7ilfl.b/+4f*l e dsk tibc tude.

  How much heat (in joules) is required to raise the temperature of 30.0 kg of wa6q8hl.x u m, m;qfv2:gjec nt2ter frot;,nemq8u2jgqc x.: vf hlm26m 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 initially 4 - hwm9zqfb0nhubgm cwz:3.9 at 10w-bf4 9cgh09zun 3mwm.:qhz b.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 250a yl mvg9blg:xb 00.ae f7y,3s0 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 thsfg6 /nj tzcyi w; -:84jubf q/rr9:oce British system of units. One Btu is defined as the heat b nrcj ;6jq4fs i/t9y-:/: rczgf uw8oneeded to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genee*m3 i3cg9oen/n2dj srate $32,000\,kJ/h$ 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 take ( x(crc zk:ca2to heat a cup of sc caxzk:((r2coup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brakes are used to bring a 1200-x pxg*pg ;zm42s 5f7izo7) jre6n9zmokg car to rest from a speeem9)xz;7z f2* 5 pgxo7mi6nop4grz jsd of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does it absorb7 csxurq8yyr3yan* :sws (,7 m if its trr:s x 7q m(ynw aucs,*7yy8s3emperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substanceq)shtxjf* 00txm8 f6 l if 135 kJ of heat is needed to raise 5.1 kg s )f80hxt0t mlfj*6xqof the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, anr 190n j7;opl q)o7im htlv2pvd water experience the same temperature rise when they absorb the sam)2p7 m ovoilh vqpr1ljt;09 n7e amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer readsfb:h8 iack :e; 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-ryt2.zcxkg eu6 b27l-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 (massl40z -djbodyo/.y +qi us*k +j = $0.4\,kg$) 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 8q 5x5xzi-67u3ndmr *dxa/bb ukhi0f 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 0.75gxveg1l))j4 r;d-0gd0uoer n L of water initially ag ve4)dxe gu0gl;n0-r j1or d)t 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 contex/oz6w z6grt- nt of 75 g of candy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup zwr 6to-/gxz 6of 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 of23v7j9w6aswjfm1k) + tahbaq9kcnc 0 iron 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 hamme+ npz6yc u1bc;r 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 needed t3ng y-p( ,1y7jqze/orr m odhoec:-;zo raise its temperature by 1 ejnhy-,7 mro3 :c(ge/ qoz1ro -ypd;z$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 initiallyzv )a;qdub)e)y f /es+ at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high buildpxtq q 5y/peb:60+m+lx3foe sing. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, whatypb6pme :++x5xos/0q3 lftqe is its temperature increase?    $C^{\circ}$

  During exercise, a person may gi3wku ve8 z s:6gizh;;jve off 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has been uz6wivs:g;; z 3ehj 8klost?    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 int i+bj1n kh e44fvr7)ywo an insulated container of liquid nitrogen. How much nitrogen evaporates if it is at its boil1kjw 7e+ibr4) fy4nv hing 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 fromncgzjbz ;uka0 3 1okd:b727a*qvm o e- 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 -.)vpl-);cw)bqlgtfjowx, s a - 4zqd230 kg contains 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 fof4iumlzkk()nqtn(wz 9 e)i, .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 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.m4(nz)lkut we9 (kiqz,.) nfi)    kcal

  What mass of steam at 1ln (ran 2r goz w3rua446-kx4i00$^{\circ} C$ 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 hrd7us 0i+ rse rxbvgxc2+5ae /3r+2imercury 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 travelin67zaoqr7 hx gwt,ua96g 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-skater modf4 1nzj ):kjkving at $6.4\,m/s$ glides to a stop. Assuming the ice is at 0$^{\circ} C$ and that 50% of the heat generated by friction is absorbed by the ice, how much ice melts?    g

  At a crime scene, the forensic investigator notes that the 8.2-g lead v zk8gg,kh7cu.dj1 6j ,mtj7pbullet that was stopped in a doorframe apparently melted completely on impact. Assuming the bullet was fired at room temperat uh7kmpck7,g6zvj1 . , tgjd8jure (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 0wfvx:wn +k 66uicp f2rod 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 ka99qkv7 nv4b i1x6zcExample 14–10, assuming that there are strong gu n cqkvi649xbavk9z17sty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is ra9 yst)z/p8p nqo-ewvaq,h n; :diated 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 skms/ :n eos9zos/q 3f 4f;u8f; tosnl*fin. Suppose 200 W of heat flows by conduction from the blood capillaries beneath the sk;lz e;o fsf so9:/qm8sf/n ft*4 nuos3in 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 1,:vgmd e) zp2t2-cm-thick brick wall. Because of a number of 1) gm:p 2vdezt,00-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 Su(dz7hq(m lt 8yfeai0/ vm41 o8man) bcn to melt 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 cross-sectioq g*xnzvzu / 977xgz0 cvb(w9wnal area are attached end to end (Fig. 14–18). The copper end is/7w (cz9 9gqb*g07uxvn wv zxz placed in a furnace maintained at a constant temperature of 250$^{\circ} C$. The aluminum end is placed in an ice bath held at constant temperature of 0.0$^{\circ} C$ . Calculate the temperature at the point where the two rods are joined.    $^{\circ} C$

  (a) Using the solar constant, estimate the ratjzb-b;z 9l 13f0fibijr )7 vfye at which the whole Earth receives en 1 j9rvbiflz;y 3fjz7f-ib 0)bergy 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 32icle-3o e o+-uzdp uof heat, which is dissipated through a glass bulb that has a radius of 3.0 cm andu3 l-ie3 z2ocou +ped- is 1.0 mm thick. What is 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 m )smh2 4-r-ndz-pgk zzk7n :piainly 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 its total area kz)2p gsn7-h-z pm:-krn d4z iis $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed window has two panes of glass separated by an airwtu8:hsn b1 1v cp2ko6 space, Fig. 14–20. (a) Show that the rate of heat flow through such a window by conductionb18wksh:no2p 16vut c 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 takit,62ij buszyww/a f y7ui+-2e 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 containsugq d/ff+8 8wl3o) lsy about 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 cont+ 2;je *:ntbzmbms8n gained in the world’s oceans, estimate the heat liberated when a cznbtgm + 2nemb s:;*j8ube of ocean 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 a fixed block of wood with aazp7 h:o *t; l jrx09d1ehsg;i mass of 1.05tpj g0os9lh; x;1ai*:e7 zrhd 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 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, ass 7sc:mwq1q.vgo-l; xcuming it to be a perfect emi lm7-: qgxvw;c1c o.sqtter 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-kg63 .gx/fq);l q uj:8-unkj(tejqf zdy 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 k8lm9wc9r (o8m.acd tdw 9ck *and falls a vertical height of 140 md 8wmtaw9dl*k9k ccmr98co.( before striking the ground. Estimate the temperature rise of the rock if 50% of the heat generated remains in the rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into aw7 1rqjhtk:3 s 2.5-L insulated pail of water initially at 2t3kqjs h r1w:70.0$^{\circ} C$. If the final temperature of the water–lead combination is 28.0$^{\circ} C$, what was the initial temperature of the lead ball?    $^{\circ}C $

  A mountain climber wears a goose down jacket 3.5 cm thic4 a jp:4 8zvc3gkmapq-k with total surface area mc4a gpzp:jv -48k3qa $1.2\,m^2$ 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 rate f6/1c4p t/y;o*aey3de fs1 es -jht wdof 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 iuhr5-i rqa3 q i,n*/pf vxx8c5nterior of the body to the surface. Assume that the th38u rf 5x*iqv nq5 xh,cp/r-iaickness 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 17.51z6m j1/lhd dvburg8ng9(;s a cm thick (assume conductivity of air) and lb /9nga(dg;d61rh j81mv usz area $410\,m^2$ 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 trave1:amhni/ . nplzxhh3ms0q ( h8w(:ytr) n yrv(ling 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 Problcm/ qn*sf/o5 lem 58, take into account radiation from the leaf to calculate how much water must be transpired (e*msl/nf/c q o5vaporated) 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 t+ b* rfhi:/oeiwojk-ek92 2ytemperatw2 j:ibfrek/-i2 eth*9 o+y okure 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 about 18cr j maakfr l255wyksr096a cr8 w0 ,d0zhth,.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. 14–22g7a- 6z(6i(yiuolx;qy yqv/x ), two people hit a soft rubber ball at a wall until they are about to drop due to xyia; 6y/ gx (( -q67yvzouqlidehydration and exhaustion. Assume that the ball hits the wall at a velocity of $22\,m/s$ and bounces back with a velocity of $12\,m/s$ and that the kinetic energy lost in the process heats the ball. What will be the temperature increase of the ball after one bounce? (The specific heat of rubber is about $1200\,J/kg\,$$\cdot\,C$)    $C^{\circ} $

What will be the final result when equal masses of ice atbbj/y5 z02 pet 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose hea);hm/ ftml66pcnw kk 1t by conduction and radiation at a rate of about 200 W. Estimate how long it would take for the bod kh pml fn1w66);cmk/ty 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 dishwashi; /5h sx9ll 65k3blmlossk nr;ng, there is “no hot water” left in the 50-gal (185-L) wat 59bnk lmlho3r;/ s;llx 56skser heater. This suggests that the tank has emptied and refilled with water at roughly 10$^{\circ} C$. (a) How much energy does it take to reheat the water to 50$^{\circ} C$? (b) How long would it take if the heater output is 9500 W?    s

  The temperature of the glass surface of a 60-W n/j e mez-cd77e py4e:+d jgx(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.    $^{\circ} C$