What happens to the work done when a jar of orange0 :v5jfa zz1 9mubhril..;v fw*z0e ti juice is vigorously shaken?

When a hot object warms a cooler object, does5rhv9)bu ;tv,; vl rov temperature flow between them? Are the temperature v;r5b r9t);vv ho l,vuchanges of the two objects equal?

(a) If two objects of different temperatures are placed in contact, wiie( uiwi m9)i cvb :(sdff79(tll heat naturally flow from the object with high:f7iu9()f d isvi( icm9b(etwer 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 temperatx qbu/(p8w/of ure may drop below freezing a few times in the winter, the destruction fpx/w (oub/8qof 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 wa 0ful 8op)t+uxter particularly good for heating systems (that is, hot-water radiators+xp 80o )uultf).

Why does water in a metal c46qtkc(cac(pm1 :e6plzs3 ebkb9 i. panteen stay cooler if the cloth jacket surrounding the canteen is kept moakp(e :6lcpsb9(c c.be6 t 1zi mq3kp4ist?

Explain why burns caused by steam on the skin are often more severe r ow4 tbo1 r ci7d3w;2wvc;ud:than burns caused by w;o 4w1ir7ctv;bd 23w:co w rduater at 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it evaporate d0f 6 pmi7l,cf.ql*fos, using the concepts of latent heat and internal ,cf6*i .f0l of 7pdlmqenergy.

Will potatoes cook faster n 5xd;dud.)fm9 knai0if the water is boiling faster?

Does an ordinary electric fan cool the air? Why or why nml +o; ys8y/c2ojy 6acot? If not, why use it?

Very high in the Earth’s atmosphere, the temperature ca 5i7 q8 kyds+ 3f65.av;k*ctfvs iyyfen be 700 $^{\circ} C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expedition- 7ndx;mcl w5ls,w 3xus have survived by covering themselves with snow. Why wouldn35;m7ulxwxcl, ws-d they do that?

Why is wet sand at the b531tpn utz sy:each cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that mean that ,a0 p 3 w bsylpa:)u/9o1yv2zxhbd d7cits temperature isbv1cd9ap3/w7 pob)lsy0 zau dh2 :x, y high? Explain.

When hot-air furnaces are used to heat a house, why is it impor wty5dimp1 4n,tant that there be a vent for air to return to the furnace? What happens if this vent is blocked by a 4n,51twiyd mpbookcase?

Ceiling fans are sometimes rec8v7: .j e b5fx5vyjycversible, so that they drive the air down in one season and pull it up in another season. Which way shoul75vyec8y c:v.bfjxj5d you set the fan for summer? For winter?

Down sleeping bags and parkas are often specw 48w66 we4sl u1nlewykds+ -pified as so many inches or centimeters of loft, the actual thickness of the garme ukws yl1e4e-66ww ls+dpn48w nt when it is fluffed up. Explain.

Microprocessor chips have a “heat 7q+asx u2*taesink” glued on top that looks like a series of fins. Why is it shaped li2ux+ 7aq* seatke that?

Sea breezes are often encountered on sunny days at the shorsm avfx7d j2,g/r-3bpe of a large body of water. Explain in light of the fact that the temperature of the land rises more rapidly than that ovgmp j/d2rx3f 7-ba,s f the nearby water.

The floor of a house on a foundation under which the air can flow is often coole1t fkqtu 9ti. :+t1r:qm. gfq3n2lznu r than a floor that rests directly on the ground (such as a concrete slab foundation). Ext t.n 2f+9imn: 1k zqq3gr.l:uftu1qtplain.

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

Explain why air temperaturar(sl* gk44 mqe readings are always taken with the thermometer in the shmlagr* 4ks(q 4ade.

A premature baby in an incubator can be dangerously cooled even when th .-9 .ctfhohgycs84 raf,zyggel u--9e air temgy-8zr .,ohaets4g.h - cug9f-lcy f9perature in the incubator is warm. Explain.

Why is the liner of a thermos bottle silvered (Fig. 14–15), and why d+k7gu:,a sg twoes it have a vac+:ag, skwgut 7uum between its two walls?

Imagine you have a wall that is very well insulated — hw*a8-4 fzfodahu2o(tv-cx*i -i 9jgit has a very high thermal resi (do--*ai8w 9aihjzt f4v*gfc u2hxo-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 following processes: (1) ventilation l vjr)r uuu075around edges; (2) through the frame, particularly if it is metal; (3) through the glass panv0ujl)ur5u r7es; 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 absorbs morq lfbgb9xxmnl,32nk3 u,+8rxe heat than a piece of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Explain.n9b,2lfnux 8,xgb mxl q 3rk+3

The Earth cools off at night much more quickly when )za9c6k)htew 3i x8 qrthe weather is clear than when zi3 c)8hrax w69 ke)tqcloudy. Why?

An “emergency blanket” is a /v9gz .*19 jm+iodly vr7dfttthin shiny (metal coated) plastic foil. Explain how it can help to keep /.yd7 lgv9 d tvf jtr1i*zo+9man immobile person warm.

Explain why cities situated by the ocean tend to hra 51.xoh s23p loh6nqave less extreme temperatures than inland citxqs5r.hp6ah12 ol on3ies at the same latitude.

  How much heat (in joules) is required ta7t mspm:gf1rta dj2kj y738j 2 yr:)fo raise the temperature of 30.0 kg of watek td2ma2rry 3ts 18:7fmg yaj:fj)7 jpr from 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg ospdn qli4t2zwa( .t+8/p6 x zef water that is initially adw 6n/(28+i sap .4etz plxtqzt 10.0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consumes about 2500 Cal a-ij6k v7 ujqevi3 :o5s 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 (tts meg-yz1tg*5/ ;n xBtu) is a unit of heat in the British system of units. One Btu is defined as the heat needed to raise ;ng1x*mgz5-/ ytst et1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generate zk . u+y 4pd.7/vllnfunt ni1:$32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater o5 ,hi0w2 flzeis rated at 350 W. Estimate how long it will take to heat a cup of soup (fle wz5h,o20i assume this is 250 mL of water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalories arn-5 h ,oya(qsffgtne 3 62nh0be generated when the brakes are used to bring a 1200-kg car to rest from a ,t-febqhh( s6f50g3na n2yonspeed of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. How much heat does b; wm+0 sjog w)yf9rlsq:nhh +t6iu-+it absorb if its temperature +: 6 lut fsh+9girbswhy;qw)+j0m-no rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal substance if 135 kJ of heat is needed to ra5 x ip,7ilx05lob ock97by8kex2b1lt ise 5.1 kg xbeb xtil8io 57yl2 0,x17o9p kl5k bcof the metal from 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, a5 izw m-- smlq;k8eej5nd water experience the same temperature rise when they absorb the same amount of heat. What is the rati5w-qj e5-;s l8zemikmo of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 2o2ai gw4o+q1w1.6$^{\circ} C$ before it is placed in 135 mL of water. When the water and thermometer come to equilibrium, the thermometer reads 39.2$^{\circ} C$ . What was the original temperature of the water?$T_{iH_2O}$ =    $^{\circ}C $

  What will be the equilibrium temperature when a 245-g block ofwnd- j jh+/ep- 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 (mass = i09uikgw3l5 o$0.4\,kg$) 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 330r8g- 4j3 bf, s)nbh/ r5nuy2bcm3txwn $^{\circ} C$ 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 y,2he ybzo enzsnq;6xf-o2/ + of water initiaobsno,62z y-+/qhx zf;n2 eeylly 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 following measurj sz,l.1t vq,kements. 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 vq1k.t ,sjlz,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 jwg: lh,8t46a nzv mbtstq);8at 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 hammtmn p0f4rhy 5w/4(jb.c*i0 c.qfdr wwer 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.gw*tf /vb0iyx+ zk6i of heat needed to raise its te* 6iwybg0 t.x /izvf+kmperature 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 -h *jir)3mwny/ zke9me+qnl 8melt 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 0br8uz8c0 snh-high building. If 65% of the thermal energy produced when it hits the ground is absorbed by the sphere, wha s8z0ncu h8rb0t is its temperature increase?    $C^{\circ}$

  During exercise, a person may give of3mnh*l9 qve4m f 180 kcal of heat in 30 min by evaporation of water from the skin. How much q *4vem3 nhml9water 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 avjf-y ai*2 cf3lr9jh4n insulated container of liquid nitrogehlf2 ya4i*f39rjc - jvn. 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 freezer a9p5h g)vrlyo cy2p5 d)t -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 c-h) opxi(gztd/;w ev:ontains 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 rnwmzl)hc 2 0 9e;hp2uof 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 usempwn urec;h )zh0 229l during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at fsathkky37duk;y 4) *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 ofv2egmom 4 94kxf4.c5g6bcvva mercury 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 at zjp0ks 5p d:e+$250\,m/s$ 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 mov/rmhz hfso xxr+0t9rl77 g7. ving 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 invo/zmn,yjsnimt3h jwu31 5/u 0estigator notes that the 8.2-g lead bullet than smztnw5/3m01 h, ou/yju3 jit was stopped in 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 diametib/gewlv j* 4,er 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 gup(v8zf:j 5 xconduction in Example 14–10, assuming that there are str( vufgjp:85 zxong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a ;fmv gh03txl+3w9sd gpq 82zv 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 8)uel:flaf :q7q i/km 200 W of heat flows by conduction from the blood capillaries beneath the skin to the bqk8i7 / qlfe:a)u fm:lody’s surface area of $1.5\,m^2$ If the temperature difference is 0.50 $C^{\circ} $ , estimate the average distance of capillaries below the skin surface.    $ \times10^{-4 }$ m

  Two rooms, each a cube 4.0 m per side, share a 12-cm-thick bri.x )ls mm(hbsxdf3 ;y sb*x:,ubut j49ck wall. Because of a number of 100-W lightbulbs in one room, the air is 9jmtl xfxu3u4 dbx*,:b;.) mbshsys(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 me-2khrs)ys .2o*frd pelt 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 andjleb9y j3 q. vgu+be7, cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace +,yejbjgl7.qbvu3 e 9maintained 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 whole Earth receive zc0 h hu4+;6fzy;okius ener40 zckof6hyuz +; iu;hgy 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 thrgrrpqn* 2-gj h/eqw- u8uf9h*ough 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 surfaces of the glas*9 h-r*u/-h8qwfq2u jrggpne s?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house come m(aa)uoin1dfvmg mqdf(9epz )s *9x81ainly from a 4.0-in. layer of brick and an R-19 lay f zfpne1s99 d) aqmxog(a1mu8i )dv(*er 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 window has two pan s5q5g p52 oyj;h82gdq9fkkbd es of glass separated by an air space, Fig. 14–20. (a) Show that the rate of heat flow through such aby ;5 pqgsh59kq2f5d8god jk2 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 zaja8)u tfv3811.0 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 of21mb d2kxdu hf7jq0 (o(w w)ptmbtp+8 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 conth9 (8b ra m5x/w0ailuhained 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 the ocean water as pu(huax50/ h98lrw imbare water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is t6pi3mk)i p qgsae6p5* op n :7zpv.+hhested by firing it into a fixed block of wood with a mass of 1.05 kg. The block and imbedded bullet together.qkp*s3mp pi7in+6e)vo:z g 5hap6 h p 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 thec9u ogo0:3u4 0p dzmoq Sun, assuming it to be a per oz94 00od mquupc3:ogfect 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 person ml4iow6avsc0z2 46ijq8gwuk 3ay 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 heq6h:br my+56my 4gy uoight of 140 m before striking the groumyb:y46o+gh 5ur y6m qnd. 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 pail of water initially a(ckd 738r xbjg qnh7 7jcola.gz v5:8nt 20cagq .jvbcr(d8lz8 37n77o:gxhn k 5j.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 thick with s1o n(3szve 4wukz1u .total surface area u3ezv1wss(. 4zo1n uk$1.2\,m^2$ 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 aboutox*- 4 ddbnej9 $950\,kcal/h$ 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 whic9d0vb2+wr 4nmvdl. : ;q qourch heat can be conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that thq dblo;+ 90vmdw cuqrnv.4:2re 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-insul,v :*l /*auaj,c tulwaated walls 17.5 cm thick (assume conductivity of air) and areau*vaaaul, tc lj, *w/: $410\,m^2$ 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 8h- 2/nitzblving 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 Problegtgz4 du;7 im*m 58, take into account radiation from the leaf to calculate how much water must be tr4zg*dumi 7 tg;anspired (evaporated) by the leaf per hour to maintain a temperature of 35$^{\circ} C$.    g/h

  An iron meteorite melts when it enters the Earth’s atmosphere. w d,gphf9 vesd,cer+s-h-5 )e *ll6ek If its initial temperature wasvw dss-p,e,h ed *9glck)lr5+e6 h-e f -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 adh3 s4q8 dntx1bout 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 (Fige- vr9lokq/8/ yo h-a8anf*ek. 14–22), two people hit a soft rubber ball at a wall until theok 89e fyk8ohalq*/vne/r-- ay 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:m8vs4m b)tv6ut)py4 jd+s qkt 0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by conduction and e tji tecu 6;oyrs1864tm q5-iradiation at a rate of about 200 W. Estimate how long it would take for the body temps4 ce-ur iyto 6e1i5jm 6ttq;8erature 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 dishwashrka0)t0g - wcpk zwsjm b21u61ing, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tan j1w0w-6rap02k t) sckbuzgm1k 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 thes j:lr- 0piroos)aatv i0xh)//b) 7nk glass surface of a 60-W 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.    $^{\circ} C$