What happens to the work done when a jar of orange juice is vigogms papkn;8: 1-sfg (orously shaken?

When a hot object warms a cooler s -serp .2lpchp(1w +cobject, does temperature flow between them? Are the temperature changes of the two objects+e p(p1sclc s2.h-prw equal?

(a) If two objects of different temperatures are placed in contact, will heamfijb78)(h ou .1r(pojk9 up zt naturally flow from the o hojrufzkj(i)98. puob7p m(1bject 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 temper4mg) h: orv1arjcd* u3ature may drop below freezing a few times in the winter, the destruction of sensitive 14rv:ajmrcuhd )3* ogplants due to freezing can be reduced by watering them in the evening. Explain.

The specific heat of water is quite large. Explain why this o q7z:c2wjp8 v1/gvcz fact makes water particularly good /g2vz7v j z8p co1cw:qfor heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the cloth jacket sumo .hpz4ifu0 s14:sqv3h 5 hztm.g 3uarrounding the canteenm ht.p1s 4 4osgq33f5 hmvz:.ha0iuuz is kept moist?

Explain why burns caused by steam on the skin are often more severe than 5*j: f emvc/l1 /*s5crsow du7 oyne8nburns caused by w7n5sc/*um w8 y sr lc/5o v1eojef*n:dater at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evapoe)s gwhwc5 /.2:zsh bmrates, using the concep./ m2h g)bwwzs sch5:ets of latent heat and internal energy.

Will potatoes cook faster if the water is b(pg4jrei3:+ xrqe te 7oiling faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why u1fr7q3j)z: -jo1e5 k qdxcjzdse it?

Very high in the Earth’s atmosphy9i; xo-xop*h ere, the temperature can be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed h6p8fyi 8hva dxl.8+kd8uk2ob 3bvi2Arctic expeditions have survived by covering themselves with suh6k2vix8bld 2b3fk.d ip8+hy8o 8avnow. Why would they do that?

Why is wet sand at the beach cooler to wanmabm70w(r s6 byj2b3lk on than dry sand?

If you hear that an object has “high heat content,” does that mean that *ki vtjaasr/ tc: t)*/its temperature is higr):/i**tkt ajsvat c/ h? Explain.

When hot-air furnaces are used to heat a house, why is it wr a+z -zk8fl,important that there be a vent for air to return to the furnace? What happens if this vent is blocked b+azkfzw r8,l -y a bookcase?

Ceiling fans are sometimes reversible n 7d crupkv8u al01e kj;5y16uvjyx7t+q1,tx, so that they drive the air down in one season and pull it up in another season. Which way should you set the fan for s;x57p7lyuuty j tu68+1krv knev11cj xq ad0 ,ummer? For winter?

Down sleeping bags and parkas are often specified as so many inches or centi1r1 jw8xlz gr1meters of loft, the actual thickness of the garment when it is fl1gxwr8rz1 jl 1uffed up. Explain.

Microprocessor chips have a “heat sink” glued on top that looks v2en9t(jin9g like a series of fins. Whni29n9vjt( eg y is it shaped like that?

Sea breezes are often encountered on sunny days at the shore9. 8a mwz0kxnn of a large body of water. Explain in light of the fact that the temperature of the land rises mw8nm0a x9 .zknore rapidly than that of the nearby water.

The floor of a house on a foundation under whidw( 8b97wjh xlch the air can flow is often cooler than 7lb9(wxhjd w8 a floor 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(l4dslgnz gxx 8fw1*y u 8 ag0we0f/j) are always taken with the thermometer in thg zdxwf/gl8y)es1 fwa4n0 8x*(lu0 j ge shade.

A premature baby in an incubator can be dangerously coo 67jsilolhj1 +8tl ht3led even when the air temperature in the incubator is warm. Explaijsthlll7i83o +j ht61 n.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why does it 2jpls9 k 7duc5qz0yp8 have a vacuum between 97 zcy08usp2qjp k5ld its two walls?

Imagine you have a wall x o,ptt w)6k6)gv,rp rthat is very well insulated — it has a very high thermal resi xt, t)ppkr,66g o)rvwstance, $R_1$ 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+ c3drq -wqw+w the following 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 radiation? (b) Heavy curtains reduce wwwq3+r+d q-cwhich of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs f*6m swq4gur l .,i.sitf7y auk94+t imore heat than a piece of shiny metal. Yet the wood feels il,4a.k y mrug*+i6f4s .iu q7s9tftw less hot than the metal when you pick it up. Explain.

The Earth cools off at night much u owd8dmvs3;f .rwd9j6 fq)1w more quickly when the weather is clear than when clou8f d;m)1j9ds.wf3dvo6 r qwwudy. Why?

An “emergency blanket” is a t/+fripa2sv/b g h)ubq, o c);thin shiny (metal coated) plastic foil. Explain how it can help to keep an imcr+igv2 )u a/ /,pfoh;sbbqt)mobile person warm.

Explain why cities situated by the ocean tend to have less ext2zr49a. g/a,zxklr:/ t36uwact q fwdreme temperatures than inland citiesa3 zfx 9rga,ckw z /6wt:a dlqu.42/rt at the same latitude.

  How much heat (in joules) is required to raise the temperature of 30.0 kg of waqvp;,n mersj (5n.qc5ter from 1s5(qqnpc m jev 5rn;.,5 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water tha+tp3*lnsh n+l t is initially n+n+lt l3h *spat 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consum 3axjqswdt1 9xl )u6)mes about 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 units.uew k (:xfppu-n m0. :jy+wr;t One Btu is defined as the heat needed to raise 1 lb of water by 1 Fkxm;jr (w-npw::ue +u 0pyt. f $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can gci u2:bkyhqay8poea-x4 2 6)ienerate $32,000\,kJ/h$ 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. Estimate0knxlym+67(.jmfdk f how long it will take to heat a cup of soup (assume this is 250 mL of wate0n m( x j7mkf.dfylk+6r) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories are generated when the x+cvlbh)z 4b+6i l( fgbrakes are used to bring a 1200-kg car to resthblcf+(+ g xi bl)64zv from a speed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L 0onsxwfe h ;,*v0zg7dof water. How much heat does it absorb if its temperature rises from 2e;f0wnogx h z*,sdv07 0$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is nr4uikb ,2itm :eeded to raise 5.1 kg of the u2mribk ,it:4metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same tempera//.efsu4g8 p g0ls8omw+m f xwture rise when they absorb the same amount of heat. What is theuffxw e w /8.o0+/ gl48mspmgs ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads// 910xwb oqgrmif-tz 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 blo1;5orfgfw + 1r tn:ea*9umbpuck 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 (masoq jh9c/gu /m,s = $0.4\,kg$) 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, q5ea advuj,w1j7u8b 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 bring to a boil 0.7hjp8le9m;p d)0 )qq9uksp n v15 L of water initip pd)8u9se9)vp nj; 0qkhm1qlally at 8.0$^{\circ}C$? Assume that the part of the pot which is heated with the water is made of 360 g of aluminum, and that no water boils away. $\approx$    min (Round to the nearest integer)

  Estimate the Calorie content of 75 g of candy from the followid/t/- pv4f uesng measurements. A 15-g sample of the candy is allowed to dry before puttintu /f pve/ds4-g 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 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 o*f .8t y.wwcp 1pqm6hoktc)8 lf 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 hammer has a sf24 mg2jn9s c25gxyfd40cu2lo hg1cppeed 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 to p 29vkfujx3 q/ovo0p 4*. k(rcod avl3raisek3vvo o*/x2vp30 pjru(fcqak d.o 49l 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 melt 16.50 kg of si5e a7bojyizg:34u6 wtlver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from the roof o7q v/ /vs+ufj.kb .q7rxrlt /hf 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 qr/ r./vh+q7.k tsfuj7b/ vxltemperature increase?    $C^{\circ}$

  During exercise, a person may give off 180 kcal of heat in 30 min by evaporgdau 37egl3v42bqv8zl u9 y9dation of water from the skin. How much water has be4gg7vdy vbl9a32du l z398equ en 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 container nunv* 0i10xr7 wcm wqx r1.:vjof liquid ni nwur1 0:.nv70c v1jmrwq*x ixtrogen. How much nitrogen evaporates if 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 taken from the freezerm am:y7 iasak1 f*a*;z 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 cozs zkdaxm(,;9ntains 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 cfi iav9caw ;ve:72( )1x j77gangmytbicyclist 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, )y7 im eigx9c t:17n(a2cjg;7avfvw a so our approximation is not far off.)    kcal

  What mass of steam at urd2v 1ym8e (,w gx6lvebfj 5gq+j er/b+s32u100$^{\circ} C$ 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 me/ gz9xvsym16i rcury 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 travel3js6mf; dce7wing 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-skaterik);7ckzx3 )l ezsj)b 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 the 8.2-g lead bulllyck m 1pay+52et that was stopped in a doorframe apparently melted completely y+kmc2l5a 1py 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-liryh wn0)qk:612o6mxhaf,ih ong aluminum rod with a diameter of 2.0 cm is kept at 460$^{\circ} C$ , and the other is immersed in water at 22$^{\circ} C$ . Calculate the heat conduction rate along the rod.    W

  Calculate the rate of heat flow by conduct4l 6ehelgr +i tz7m9-rurnp, :ion in Example 14–10, assuming that there are strong gusty winds and the external tempe9hiu rlmp r-n ze6 ,t+7r:gle4rature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissidw4 k48 slxvo)vity $e\,=\,0.35$) 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.y* 3 mi;k38b ij2ebx+trywbb conduction from the blood capillaries bewr2jy m 3xyb; * 8bb.kb+teii3neath 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 perg )pr,gs0t x-w side, share a 12-cm-thick brick wall. Because of a number of 100-W light-w ,gp0x)st rgbulbs 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 oovk jc,7x1z9it-5utn 2wcc 9+ ycxee +f ice at 0$^{\circ} C$ with a flat horizontal area $1.0\,m^2$ and thickness 1.0 cm? Assume that the Sun’s rays make an angle of 30$^{\circ} $ with the vertical and that the emissivity of ice is 0.050.    h

  A copper rod and an aluminum rod of the same length and cross-sectional area ar cpek p :z;i8a xw(/+iyx:n3qge attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature of:;(yiizn k+xap8 c:wg /qp xe3 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-z-s3fg:( fmnsh5 lz o rate at which the whole Earth receives energy from the Sunn5sh(gm o-sz- fz 3lf:.    $ \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 ge 0tf4qntel8 h h 7b6h(t: haun+8qx,wwnerates 95 W 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 difference in temperature between the inner and outer surff an,ehtq(th8t4 h+ 8wn6h bwxuq7l: 0aces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come mainlyiok8e, urr - 4zjeun)4q:h;bq from a 4.0-in. layer of brick and an R-19 layer of insulation, as shouz-j8h : neurqe 44)kobi ,;qrwn 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 n hj6a5 t6in,1i5x r0o oqw3uvof glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flo6w,65i3 ih05xaov 1uqjtrnnow 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 it0b68tq :bwsyal yy79 m 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 contains about 0.20 kg of liquid atoip 35lt*vq lw:b80ih 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 76w d,:l rxuyzin the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 km on each side, is cooled brx 76 w,:yudzly 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by ;dgyc9c8i18jwi o, kh firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. After thermal equilibrium,j w8cockidy ;8hi1g9 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 rn/z35+ hld cz6lyiiow/+d5n Sun, assuming it to be a perfect em+ r n3lizl+ny56icwz/h/o5 dditter 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 person may genurvh/e+g)vto b:+i+ rphfap 7+p19 aaerate $200kcal/h$ 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 px9m4(/8 ,himjnth wmoff the top of a cliff and falls a vertical height of 140 m before sm 9hmt8mixn, 4hj(/p wtriking 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 )w )6ljpnwrte2ns0(e) i+xto into a 2.5-L insulated pail of water initially at 20.0xe 6tsp)n2+eil0ntw o) (r )jw$^{\circ} C$. 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 thick with tota h 9yxl7:f04t yafm1 spmcaf81l surface area s7aafyt0c hf918xf: 4yp1m ml $1.2\,m^2$ 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 ow9vzr2l *9 ivlf 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 interior bfj+6v7srm lny + 0sry- *qe4bof the body to the surface. Assume that the thickness of tissue is 4.0 -mlrn+y+v *7r ys46 ej0bfqbscm, 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 of air) ankwfk4,2 .,*zx q-qzu,ebo ms ld arkq.4 w,uqzlbf e-*mo 2ksx,z, ea $410\,m^2$ 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 m9miao68r/xsing 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 into account z)7 tz4; *pvwu *gwyxcfxd1*g radiation from the leaf to calculate how much water must be transpired (evaporated) by the leaf per hour to maintain a tempvcg*7*dz gwwpz ;4x)uy txf1*erature of 35$^{\circ} C$.    g/h

  An iron meteorite melts 4 o1eq)(lv pumwhen it enters the Earth’s atmosphere. If its initial temperaumvlpq)(1e4 o ture 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’kak vz)d)vp; ssj 0w,5s crust increases about 1.0 C$^{\circ} $ for each 30 m of depth. The thermal conductivity of the crust is $0.80\,W/C^{\circ} \cdot\,m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $ \times10^{18 }\,J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $ \times10^{4 }\,Q_{interior}$

  In a typical game of squash (Fig. 14–22), two phclg+0.dbedo:a j h71eople hit a soft rubber ball at a wall until they are about to drop due to dehydration and exhaustion. Assume that the ball hits the wall 7:oc +.d1j0heahl g dbat 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 5y5/ 1tifq2 amsukxi mucjlzl -n9.9-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 byy;whhf odzes2)n 8-q, conduction and radiation at a rate of ah)d,-fwoz q28 s e;yhnbout 200 W. Estimate how long it would take for the body temperature to drop from 36.6$^{\circ} C$ to 35.6$^{\circ} C$ if metabolism were nearly to stop. Assume a mass of 70 kg. (See Table 14–1.)    s

  After a hot shower and dishwashing, there is “no hot wat30x)vvh1 e5+rllxp jgoa8fs p8 g1ums* yi;s8er” left in the 50-gal (185-L) water heater. This suggests that +h 5p 3sxesj8y m0vu*go)vrlsl8x1g;i8f1p a 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 lightbulb is ki-2 (h 3eg5h ks re;flstb,dj0sfl7+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.    $^{\circ} C$