What happens to the work done when a jar of orange juice is vigorously shak) e )lf::l9 -gyalhgxhen?

When a hot object warms a cooler object, does tempeaez z1*hnvi/q f4d*jzbme*.v(cg1b a b,e*7i rature flow between them? Are the eez*4bnbzimfb ( e*i1z*h/aqvgv. 7d,c1j*a temperature changes of the two objects equal?

(a) If two objects of different temperatur u +i40ib-+hy*)ql c atnr/mbzes are placed in contact, will heat naturally flow from the object with higher internal energy to the object with lower interna)4uzn +h*+ ybq-/ac0tm b ilril 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 t5/ /a)sp refe8perjl 6pvs 2)nhe temperature may drop below freezing a few times in the wintersj)re e6n5s2pr/e8l/ f)p pav, the destruction of sensitive plants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this fact makes water qnu:r aji2q; o4,n lttn 05vz.particularly good for heatintiunn4ar5qj0l;2 v z :ont q,.g systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth j(h*xrh5e4e ono 1kxv:acket surrounding the canteen is kept moisn(v*oehhoke r :415xxt?

Explain why burns caused by steam on the skin are often more severe thogf624 qz.eh5 uaql/x2vu l 4tan burns caused by wateru44a e .l2 hvo2qx5f6lqz/tug at 100 $^{\circ} C$ .

Explain why water cools (i3 hj ogl)79la4l a6- wbizc:kdts temperature drops) when it evaporates, using the concepts of latent heat and int3j )l c7zo d4-wl:6 ki9baahglernal energy.

Will potatoes cook faster if the water is boiling fast oh1s(- +6ckq l.g w.)exryriger?

Does an ordinary electric fan cool the air? Why or why not? If not,)nk 5tq2ny: kw why use it?

Very high in the Earth’s atmosphere, the temperature +xl fw;i/xv 0bo5o/vh 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 cove83c dz bzw7tdwm*8ap;ring themselves with snow. Why would ctwd;8*wz7 bm zd83ap they do that?

Why is wet sand at the beach cooler to walk o6rb )-b48 lp*gwh80iiq ;5ueakjz am un than dry sand?

If you hear that an object has “high heat content,”*ttahfds zf6q1k* 3 )j does that mean that its temperature is high? Expla)3jtsqfd*6kfhz t1* a in.

When hot-air furnaces are used to heat a house, why is it i2 b;-ut6lf 4tbh gpymen34u3f mportant that there be a vent for air to return to the furyfepg24u ;b-fml3tn3th u6 4bnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometiyx4.bmx8w-twpksxx84 lh5*u mes reversible, so that they drive the air down in one season and pull it up in another s5 8 4hxkb*upxy4 .t8s mxl-xwweason. Which way should you set the fan for summer? For winter?

Down sleeping bags and parkas are o/5 yfwc+o81eczo7p flften specified as so many inches or centimeteozp7 eo18c5/ wf+ ylfcrs of loft, the actual thickness of the garment when it is fluffed up. Explain.

Microprocessor chips have 2a foyt +)yn.n 89hzpwfd: z1ya “heat sink” glued on top that looks like a series of fins. Why is it shaped like that?a.oh +td 1ffyyz2n9)wzy p:8n

Sea breezes are often encountered on sunny days at the s: m/8srwu stl/;fpah5sqo6 8 ehore of a large body of water. Explain in light of em/8s8qw:r6 ts/s hp; oal5 ufthe fact that the temperature of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under which to2 iu;/qh / ngn.smig9he air can flow is often cooler than a floor that rests directly on the ground (gih2m soq //n.gun9;isuch 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 alwa okq8xlj281z tys taken with the thermometer in the sht88xoj21zk l qade.

A premature baby in an incyzr/* h*jd2cmwtnc 7)ubator can be dangerously cooled even when the air temperature in the incubator is warm. Ecd jnhrtcz**2y7 w/) mxplain.

Why is the liner of a r(dzg )m/csuc kx;h 31thermos bottle silvered (Fig. 14–15), and why does it have z(m3 k)g1 /d xsuhcr;ca vacuum between its two walls?

Imagine you have a wall that is very well insulated — it f;4c1 9rjzzzphas a very high thermal zz4 91jfr;z cpresistance, $R_1$ 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 fol:ws hrqy 6d:9lvy 7ww8lowing processes: (1) ventilation around edges; (2) through the frame, particularly iv:7lw 8rs6d y:yqw9hwf it is metal; (3) through the glass panes; and (4) radiation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absor1 syfsg,jk0o:qy 5te-bs more heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Explat kqy0g,y j1-fs eo5:sin.

The Earth cools off at night much more quiclspxz5z7gel5+k k 8x(tqa .*dkly when the weather is clear than when * xpdzq8ts.k zael57(+ lg5x kcloudy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastic zw-f3. p v+empfoil. Explain how it can help f3p-m v z.+pweto keep an immobile person warm.

Explain why cities situated by the ocean tend to have less extreme tempf0 )avu:axp6u eratures than inland cities at: )0f6upau vax the same latitude.

  How much heat (in joules) is requ4g g+okyb mtdg;8sw 49ired to raise the temperature of 30.0 kg of water s+ggdk 48ob9 mwy;4gtfrom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg 6w we q eu/ w:+(l.b7lzdqed9yof water that is initially at 1el yl 7d( ue +w:dqw9eb6/qw.z0.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2t-ics9sdnw-rj z4 -y* j 6et:d500 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 ky yx 8919 fl;i +bxqrwruny1rw3qf, 7system of units. One Btu is defined as the heat needed to raise 1 lb +9nlrrff 1w 8q 3wiyyq x7xu9b1;, ykrof water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate .d.o3d o.rbfx $32,000\,kJ/h$ 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 h5k-:w0x +hfi4 e,6s llw j4 khn-oyip*j1sa oW. Estimate how long it will take to heatl-j p lon sxwjsi0whko k+h1 i4,f6*ey:a-5h4 a cup of soup (assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the brcn; l-yc*. cela9mh)qakes are used to bring a 1200-kg car to rest from a sp *l eclcnh.yaq9c-m;) eed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How v /i71flk 1owuduxs3.much heat does it absorb if its temperature rises fromu7v13 uswo/xf .d1lik 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of hly)fxz9-b-xd s ;8mqaeat is needed to raise 5.1 kg of the mesl9;ma- y d8xbxqz-f)tal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature rise wdlgteb *vmsd)8,b 8 g/;5beuihen they absorb the same amount of heat. What is the ratio of their masses? [Hint: See T, st ;m8) dubd blgv/b8e5eig*able 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 21tlvl/vt6vqkw 2 ad:b ( u*vq7,.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 whenxtea3u q3xo8* 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 (massnehoatb3 dk +* o5ecc17e09 ml = $0.4\,kg$) 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 syocko,gd2p; r: :q4yux7 ovep6 .t+yheated 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 7k9wy. vrm5i p w :ew.zri1.k/l50-W coffeepot to bring to a boil 0.75 L of water initially at 8l ei5mp/:9rwz.kry.wi .1w v k.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 nrv- a 0jxt6un, b 2ll:bhm(-athe following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. -bj6 nn(lx mtba: ulhva20-, rThe 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 iron *q h 8xbzp;ly +u4.bqxd77vya 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 anshhzrft9dp -3k6w9) 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 ae21derp(jsi, .z zy k+n object is defined as the amount of heat needed to raiseszk2+(jy. r, 1eiezp d 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 m.lto zsmpnce 9u /o n6*p91.kuelt 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof of a 45-m-high building. b5v6loj :zr2gIf 65% of gb:or5z 6ljv 2the thermal energy produced when it hits the ground is absorbed by the sphere, what is its temperature increase?    $C^{\circ}$

  During exercise, a person may give off e qumkw 4:lru0xnh:*t/ )y(cb180 kcal of heat in 30 min by evaporation of water from the sk *ekl/:(u: 4q wcbuxymhnt0r)in. 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 melting point is dropped into an insulated co/9zpd hd j4ls)msn )p8ntainer of liquid nitrogen. How much nitrogen evaporates if it is at its boildp/m)jds z8 4s)l9hnping point of 77 K and has a latent heat of vaporization of $200\,kJ/kg$ Assume for simplicity that the specific heat of ice is a constant and is equal to its value near its melting point.    kg

  A cube of ice is taken from the f itepur.+a 1e,reezer 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 r f:e.ie )yhes4w.h2f 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 bicycyjqep2h*h b2z p; 5l/ qf3ma:qlist consumes 8.0 L of water over the span of 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 during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, s 5 /jqmq*ae: b3ql; fzpyh2p2ho our approximation is not far off.)    kcal

  What mass of steam aaza/hr a1/q8fvpq;ykn- ,8r f t 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 mercurbr osq7cb )b9s64 psv8y is $138\,J/kg$$\cdot\,C$ Determine the latent heat of fusion of mercury using the following calorimeter data: 1.00 kg of solid Hg at its melting point of -3.9$^{\circ} C$ is placed in a 0.620-kg aluminum calorimeter with 0.400 kg of water at 12.80$^{\circ} C$ ; the resulting equilibrium temperature is 5.06$^{\circ} C$ .    $ \times10^{ 4}$ J/kg

  A 70-g bullet traveling a1wez8dq.lb8b s-ekh ; ,dea w:t $250\,m/s$ 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 movinx:sdy6t lf ctqi9v1-5g 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, theaq(rc8+i+ cu wyq0)vxs tel-0 forensic investigator notes that the 8.2-g lead bullet that was stopped in a doorframe apparently melted completqt8r+vc)se( -+0u0cxlywia q ely 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 diameterkh,itcn24vvur9+ ht 4 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, axa7kw shqn/ 97+ ejwz6m2 9oltssuming that therewze6wmos2 j7ak9hnq9 xl t+7/ are strong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is zb:)b dwk ftu2 v2-ff;)i+-zya1buoy radiated 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. Sdx n5k(xp55;adz8buv : j3ms yuppose 200 W of heat flows by conduction from the blood capillaries beneath the skin knz:3bx;y v8a5xp (s mud5dj5 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 pg2by jj uwn7 nm6vk),3er side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air is at mnguj )w2,76n y bkvj330$^{\circ} C$, 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 o:ic obf98zl*+ *gh**qt swunSun 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 0 m: ks6wgr)ucq.h9zrrod of the same length and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of r.ucq6zswrm ) h09k:g250$^{\circ} C$. 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 cons : ;vxjbzewb4 fzn37.ptant, estimate the rate at which the whole Earth receives energy from the Sun. b7: 3vpzb;fenwx 4 .jz   $ \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* y acl)fv15wh of heat, which is dissipated through a glass bulb that has a radius of 3.0 cm and is 1.0 mm thick. What is the difc1w5 lf)yh v*aference 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 4.0-rn;3 q-d el-djq*r;isin. layer i-- *lrqrd3q;d s; jenof 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 is $240ft^2$ and the temperature difference across it is 12 $F^{\circ} $?    Btu/h

A double-glazed windk z uv1m+uup:3y. yiy43kwuy* ow has two panes of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow t3*yw ku3pm:+u. zu iy1kuvyy4hrough 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 kptt9(cn *qbw; t. 2mnmg of ice at 0$^{\circ}C $ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25\,cm\times\,35\,cm\times\,55\,cm$ whose walls are 1.5 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 32$^{\circ} C$.    $ \times10^{4 }$s

  A soft-drink can contains about 0.20 kg ( lmec6yof29hof 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 isr(p8e p2.32yy wcjoto3x nt) b contained in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled by 1 K. (Approximate tx rwo3 o)p(cenb8y ty2jp.2t3he ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a ff 7s9n pf liaad2,iob/y,s8,g ixed block of wood 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 7f a,,b2igl df,8nya s9 /osipmeasured as 0.020 $C^{\circ} $. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radik .mxp6 pku qk8htgy,a/7l1o+nzpo: 1ated into space by the Sun, assuming it to be a perfect emitteonaq6t+,kgxuh8kymo lp1p/7.1 pk : zr 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-kgpy6x;p+uc 5wv f(y ad4 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 heighfbc*c+y cngh x+*3tg 9t of 140 m before striking t3n fx cychgbgc9 *t++*he 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 a 2.5-L insulated pai/wqf2h)mk zh3r 6.d -ispvp8ll of water initially at 20.0wpzk. v) f-32s8rq pi/ 6mhdhl$^{\circ} C$. 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 goo 3s,f* jf qe77n dy6pdgo4w+hkx4sb/ hse down jacket 3.5 cm thick with total surface ared7yf s wdn 7hq+sbfkx/o4e6*p 34jg,ha $1.2\,m^2$ 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 of about zrr uv je96f+0$950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which heat can be conducted from the interior of the body -0r5dmb;p9+ loa cpfx6plzs+ to the surface. Assume05+llzpp9 6o;prcdam fs-+bx that the thickness of tissue is 4.0 cm, that the skin is at 34$^{\circ}C $ and the interior at 37$^{\circ}C $, and that the surface area is $1.5\,m^2$ Compare this to the measured value of about 230 W that must be dissipated by a person working lightly. This clearly shows the necessity of convective cooling by the blood.    W

  A house has well-insulated walls 17.5 cm thick (assume conductivity ya m216 :yryhoof air) and y 1:2hyr6o mayarea $410\,m^2$ 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 travel p/iq c8tcy 3p491lpehsh.j1eing 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,kjg2;lc ) ;a2ycl (lru take into account radiation from the leaf to calculate how much water must be transpired (evaporg;lr)j (a;2lcyc 2kluated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite mela*iu oby/t,v8/hh1 chts when it enters the Earth’s atmosphere. If its initial temperature was -*/yhhi , uv1c/ha8bot125$^{\circ} C$ 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 crdth; s8 ,7skfpc.uh:n:- iuyqust 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 rubbhla8+90qa: f lp. v3obqyfyyzj+ x/ 2ser ball at a wall until they are abopyq + a. 9b3a+vyy:ljhf80xf2zso/l qut 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 yl y3*f/ne (dbequal masses of ice at 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and radiatie m5w:p16;v fo9tqjei on at a rate of abom59pwft1e:i ; jove 6qut 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 an5)pl8y dh * wso:9d:o o 6xi7zjis5sznd dishwashing, there is “no hot water” left in the 50-gal (185-L) water heater. *xo:jzsiy5:69oo7 n5sd)w si8dzphl 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 lightbulbg k gpi8)i5- d)onvnwy/ 4s,dl 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.    $^{\circ} C$