What happens to the work done when a jar of or4gs0 0sku hc5 ,q;r+-lz arsebange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them? Are2,i )zg7 dgo4ovr-sht,m;okl /r 2gx x the te;z ,2 r ,lhdg)otx-m4io/2v sxog7kgrmperature changes of the two objects equal?

(a) If two objects of different temperatures are pl +awxsedv84x4 /u8n osaced in contact, will heat naturally flow from the objec+sx8 o8un/dx 4e4wav st 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 the same? Explain.

In warm regions where tropical plants grow but the temperature may drop below f 89- lgh*l nksbb/fh7ireezing a few times in the winter, the destruction of sensitive pla b lfsg/li*k9h7n8hb -nts due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of( , jkqb6ldpjm2j7z 7y water is quite large. Explain why this fact makes water particularly good for 7 zjd,yb6pqm 7l(jj2k heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket surroundingoh9j kolifru4u)0: y4 the canteen is keh:j9 u4ou ky0lr )ofi4pt moist?

Explain why burns caused by steam on the skin0qy7oy56lmh2j rt+vbvenvme;*;d5 a are often more severe than burns causm+6y;rmdeov75vq e l ;njb*ya20v ht5ed by water at 100 $^{\circ} C$ .

Explain why water cools (i5rtbiypnd 5mi / 2m.uzq7e 0q4ts temperature drops) when it evaporates, using the co0zr.5i q2iye5 4u/dnmm7 tpq bncepts of latent heat and internal energy.

Will potatoes cook faster if the water is boiling fnqz oj/ v(*6f ap2+ageaster?

Does an ordinary electric fanfv25 u ux4j*ar cool the air? Why or why not? If not, why use it?

Very high in the Earth’s atmosphere, the temperat0/uxwis87 s +3r9oosd +e5xbnbdfq6sure can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic*pi(4 adl fp:g expeditions have survived by covering themselves with snow. Wp4g:(api*f dl hy would they do that?

Why is wet sand at the beach cooler to walk on th 01 ovuijd1+w4w0tkhnan dry sand?

If you hear that an object has “high heat contenthq11glwgq*r d1 o)z 4p,” does that mean that its temperature is 11 qrqg*o4g1 )p dlhwzhigh? Explain.

When hot-air furnaces are used to heat a ho4x i.tw-0mgjyuse, why is it important that there be a vent for air to return to the furnace? What hapt0mix.-jyg w 4pens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so t0qnur48 n:yvm6 k x*khhat they drive the air down in one season and pull q r *0h xnuyvk468n:mkit up in another season. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkaseqkg+ 53 2iebl are often specified as so many inches or centimeters of loft, the actual thickness of the garment when it i 3qleek25+ gbis fluffed up. Explain.

Microprocessor chips have a “heat sink” glued on 0l :*fogc4uv ztop that looks like a series ofz*gf c0uovl:4 fins. Why is it shaped like that?

Sea breezes are often encodm 0,i4s ge ft:f(lj6mc-9 gdzuntered 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 d zds9 tj04( ,cg:f e-gi6lmmfthan that of the nearby water.

The floor of a housezq7ran9/lwd p k wqe-( 8tnusa,8k61m on a foundation under which the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete lw kna nt18qw ,8mudzs7pq6kr e( a-9/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 with the thermometer in th)o.bahk voz vt:b3 g5i0wn (2se shade. oti(okn2.wbb h0vvz g:sa) 35

A premature baby in an incubator can be dangerously cooled jti v ,:)ta7 c3vleb-ceven when the air temperatvve a lt) :t-3ijc7b,cure in the incubator is warm. Explain.

Why is the liner of a thermos bottlioyt o7/vb9(me silvered (Fig. 14–15), and why does it have a vacuum between its tbo im9(ov7y/ two walls?

Imagine you have a wall that is very well insulated — it has a veryjg;, gxcgs0+ajrg: u. high thermal resi0 x,gug.rjc+g;g:asj stance, $R_1$ 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 fo7qq a6pq 5s() t0u/ii9hztyw allowing processes: (1) 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): conduction, convection, or radiati w sqayq)i057iu(t9a tp/hz6qon? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun abyqw .c:ec8u9x/q 2gu ysorbs more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you uq8/g9 exquc yw2 :y.cpick it up. Explain.

The Earth cools off at night much more quickly when the weather is clear than wvq7b3.n li3 gzh37 gizn3 lqvb.en cloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) :lnebma2oipb 3(5 8cc plastic foil. Explain how oc5 li:2(cbp an 3e8mbit can help to keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme 8:; (e- ixtbet+t8 cec/cdhzbtemperatures than inland citie(etz/dc tb b:c88eit-ec;hx+s at the same latitude.

  How much heat (in joules) is required to raise the z ppwmu 3w*txinv -c.a55+qb* temperature of 30.0 kg of water fv w-ppwnx 5cz.tami+buq*5* 3 rom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kupevgb9;4/ ah g of water that is initially at/p9bvg;hea4 u 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes aboz45 wb / jft 58;jdp0bh;d*wgvflz3vvut 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 unicu2tnf2;u 9dv ts. One Btu is defined as the heat needed to ra 9 fvunud;tc22ise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate vf8cxw/ch)v /$32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion hea rvgaag3:7v1 3sjfw,e; ed9m nter is rated at 350 W. Estimate how long it will take to heat f :j;nmv3 eg,s a1grw7a 3d9eva cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated whyp*el xvlw3bf 47c0 c2r60wog r6lp+men the brakes are used to bring a 1200-kg car to rest from a speed ov6l2xbe olc4c3*ly pr7fgp 0wr06w m +f $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat domdqq*;k ngji+pn7( j/es it absorb if its tqj7/ +ng;j (nd k*pqmiemperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substx);;lgxihj(zu (/ wq nance if 135 kJ of heat is needed to raise 5.1 kg of the xug; ()/xjzn( q i;hlwmetal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same tempeie u/ ht8dr irg+3qs/t ;k -;ix6wwjy0rature rise when they absorb the same amo/; wxge 6iur shj+i3i -;tytdr/kqw80unt 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 thermometerkqkzkpjv4m3 ( amg:( 4 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 ). k zk ju4ndet*ml4t9temperature 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 (mbum*c5s yf3g (tnbn) 50lj.spass = $0.4\,kg$) 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 yxzn(w i6b mru06mi3;330$^{\circ} C$ and then plunged into a 105-g aluminum calorimeter cup containing 165 g of water and a 17-g glass thermometer at 12.5$^{\circ} C$ . The final temperature is 35.0$^{\circ} C$ . What is the specific heat of the substance? (Assume no water boils away.)    $J/kg \cdot C^{\circ} $

  How long does it take a 750-W coffeepot to bring to a boil 0.75 L of w d23tome3kbc zu 3e2c*ater initially at 3*otz 3eu 22kbe3mdcc8.0$^{\circ}C$? 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 fol n+dm: fwil0(plowing 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 of mass 0.624 kg. The initial tempermip+nf:d( w0lature 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 iron atox c(i8j twan)cge*4 /tnl) t6 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 speed qlno:3:pn8c7t sblcr h5e x5 0of $6.5\,m/s$ 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 needa6g lp6pkvs po t/)c;g(s+ s/bed to raise itsp6+6pg;k)bcvgla s s/t/o (sp 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 neededzir7nu)il 9 lc2gi ik o843.pk to melt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is drop0 *2,ff8 -okecxpnc bpped from the roof of a 45-m-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperaturefbfc kp8x2en-* 0ocp, increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 307kny ;mczr8ea+jlf 9:;tcnee(l4ih (58pvx j min by evaporation of water rl(;5pc:y nzjee9xncl;k8h (84tmja v+f7ie 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 itse9vj5cz+ -e yx melting point is dropped into an insulated container of liquid nitrogen. How much nitrogen evaporates if 9xeyc5j-v e+z 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 taketd4 p8u./x jgmomyn; x78 vbi5n from the freezer at -8.5 $^{\circ} C$ and placed in a 95-g aluminum calorimeter filled with 310 g of water at room temperature of 20.0$^{\circ} C$. The final situation is observed to be all water at 17.0$^{\circ} C$. What was the mass of the ice cube?    $ \times10^{-3 }$ kg

  An iron boiler of mass 230 kg contains;.l2lqu x(h 7,ic tuno 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 oyxluiev *w rm.3zg)0rf ;j)o/f four 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 oyi./rr)3;z* ugm jw 0exl )vfduring 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 at19 .mdpakjfs+ 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 mercursb4t-a jc q0p5y 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 travelingwd n)-8*h9ikfsaslb iz-3rz1 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-skatergi y*ii; ddznat/bys45/6 k5z 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 thed*j22, mpf fmk-5hj+rd/t 0q lymepc( 8.2-g lead bullet that was stopped im k m0erm*qd +2dffpt-jly, hc2 /(j5pn a doorframe 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 dy3yhx p) 1ecph)9qh( iiameter 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 conductiovmcim cb.:c )(n in Example 14–10, assuming that there(vcc bi)mc:m. are strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiav ozj)di2k:pt+t.egj)tf 8 s7ted 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 frows*d / zafnb7b :,7+zc1 bhrnvm the blood capillaries beneath the skin to the body’s surfa 7z:+7 vr b sf*wz1bn/cnhdba,ce 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 4.0ax1dwx7 e,5j*abwo k- m per side, share a 12-cm-thick brick wall. Because of a number jwx5 *o-a e,1dxak 7wbof 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 msy *dkjsib 9nn 4** wlrfc(m 31j06t,bols/xselt 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-sectional wh xfapyhju.z,*,q3 6 area are attached end to end (Fig. 14–18). The copper end is placed infwa3z*, ,h.pu jh y6qx 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 rate at which the ka;p/ ikk*,a u .(awciwhole Earth receives ek /iiakap(uw ;, kac.*nergy from the Sun.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of heat, which is dissipated through a ftvz 0r /giby3g edo-v/q k/)1glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the diei t/f-0/ yvzqgo)dk r31b/v gfference 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 frf;3n dx ,sy0xc7jp;inom a 4.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What is the tojsc0xp;ydx7;f ,i nn3tal 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 vzia xvrlsp (4 5r.s0,panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow thr0.v a,v5is rxl(psrz4ough 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 i u0m,tr2m;mkt i7ka3ct take 11.0 kg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contaiif 7zlb .:d3c0bxr c(ans 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 contained in the world’s o9h*c 9)q, bmej(guzm kwmw1kq6(a mh :ceans, estimate the heat kmz(6hae*) 9wg:cmjwb9mq ,khm 1( quliberated when a cube 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 w/7 odv.v9tbqxood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium has been reached, the system has a temperature rise measured as 0.02qv79b .d/ toxv0 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radi)picl, xc k5s1ated into space by the Sun, assuming it to be a per1scxl5p,ik) c fect emitter at $T\,=\,5500K$ The Sun’s radius is $7.0 \times10^{ 8}\,m$    $ \times10^{ 26}\,W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5 \times10^{ 11}\,m$ away (Fig. 14–21).    $ \times10^{ 3}\,W/m^2$

  During light activity, a 70-kg pfz+p p1izh b2,erson 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 afm6bo ,fssn t.c1d bf)1d x/2of 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 heat generated remains in thet b 2/f6ms1n asdcx dffo)1.,b rock.    $C^{\circ} $

  A 2.3-kg lead ball is dropped into a 2.5-L insulated pail of water ini;euk:/nl 4 oa3eqe hpsske.7 yf+a4l1 tially at 2/e3+nkeeu14ae4q;hl saky sp:f7 o.l0.0$^{\circ} C$. 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 jac6:5bpjc,z4 vn6tg;m*hnr kx k ket 3.5 cm thick with total surface arektrb :h ;*,6 gncm 4n6xzkvj5pa $1.2\,m^2$ 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 aa9xb 4bwd)c: 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 whiat7ktk sb0 car1f)155b ;of oxch heat can be conducted from the interior of the body to the surface. Assume that t c5akftxks;rt)o fa051b ob71he 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 walw o +p8opemmx. r3;wx dm;8(hsls 17.5 cm thick (assume conductivity of air) and a8;oo x(e.;3ws m mp hwdx8mrp+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 trav2u; rbtzg:. lscs.m9t xb:lz3 eling at $220\,m/s$ passes through a thin wall and emerges at a speed of $160\,m/s$ If the bullet absorbs 50% of the heat generated, (a) what will be the temperature rise of the bullet? (b) If the bullet’s initial temperature was 20$^{\circ} C$, will any of the bullet melt, and if so, how much?    $C^{\circ} $

  A leaf of area $40\,cm^2$ and mass $ 4.5\times10^{-4 }\,kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80\,kcal/kg\,\cdot K$.
(a) Estimate the rate of rise of the leaf’s temperature.    $C^{\circ} $
(b) Calculate the temperature the leaf would reach if it lost all its heat by radiation to the surroundings at 20$^{\circ} $C.    $^{\circ}C $
(c) In what other ways can the heat be dissipated by the leaf?

  Using the result of part (a) in Problem 58, take iats cl6:u -t4+yi zv1anto account radiation from the leaf to calculate how much water must be transpired (evaporat46 a 1svlt+-iazyut:ced) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enter2ut s j*yx2b*g:goh7 ks the Earth’s atmosphere. If its initial temperature was s k*:bhgt72o gx2*y uj-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 abogl,jz nd.u0ge;css 7/ ut 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 squash1msg xfvp68 ligk+7. p (Fig. 14–22), two people hit a soft rubber ball at a waxl8 sfkg m16vip7+.pgll until they are about to drop due to dehydration 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 a. dt)qo s6z.xht 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by psbrv+e1hoius);71 /ho id os/ ( +ffyconduction and radiation at a rate of about 200 W. Estimate how long it would take for the body temperature d +hhus /p(vf7erb1s1si)+/ y ;fooo ito drop from 36.6$^{\circ} C$ to 35.6$^{\circ} C$ if metabolism were nearly to stop. Assume a mass of 70 kg. (See Table 14–1.)    s

  After a hot shower and dishwashing, there is “no hot wat4,yxzju f9rs q8oxn- -er” left in the 50-gal (185-L) water heater. This sugf8nox-y qr,z x4s-9jugests 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 m8;ly: *yh 0n b0omxqalightbulb 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.    $^{\circ} C$