What happens to the work done when a jar of orange juice iec0rl8 c )dmy4s vigorously shaken?

When a hot object warms a cooler object, does temperature flow between them?f;u:19qddl v;vin i6 lk/du9 e Are the temperature changes of the two objects ;;6ld/kdilu1ueq9 fvn9 iv :d equal?

(a) If two objects of differen)8iy qu:clm,jr+ sde+t temperatures are placed in contact, will heat naturally flow from the object 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 thue:l) y+ c, id+8rqmjse same? Explain.

In warm regions where tropical plants grow but the temperature may dr(z*c)ta ,-pc w ja/vdbop below freezing a few times a d(bpa/w,)jct- *czvin the winter, 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 whyhmb )*ykpdgh563jy9b d7u rbp ;36yxf this fact makes water par x hrpyg*)u9p3kyjhbdb;5y6d 736mfb ticularly good for heating systems (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if thoe 1jftc.c7/ re cloth jacket surrounding the cantt7c/fc. ej1ro een is kept moist?

Explain why burns caused by steam on the skin are often more 2pk1+w3q hk8 s5xyg.pwcxi.p severe than burns caused by water at 100 .p 2kp hgp3wyc 5ki.wx+1xsq8${}^{\circ }C$ .

Explain why water cools (its temperature drops) f6za 5 +5acypi-r:z;tput- rswhen it evaporates, using the concepts of latent heat 5+ tfs-ua -zy6tcrz a5ri:;ppand internal energy.

Will potatoes cook faster if the water is boiling 6li6 g)nf4 id6,rota ,;odw spfaster?

Does an ordinary electric fan cool the air? Why or;x 2rx-gfs0 vvump0o- why not? If not, why use it?

Very high in the Earthrd bra)e )jhh.hvx2n:.x : a9u’s atmosphere, the temperature can be 700 ${}^{\circ }C$ . Yet an animal there would freeze to death rather than roast. Explain.

Explorers on failed Arctic expeditions have survived by covering thh*mreau ;-r dyavyzd0a, h((s(bp: :r emselves with(b aa,(phhe:r*v ydrar-uzsm:; yd (0 snow. Why would they do that?

Why is wet sand at the beach 41 f2s uudxzp3cooler to walk on than dry sand?

If you hear that an object has “high heat content,” does that meawz 3 u/mmt.mz3n that its temperature is high?zzt /.m umm3w3 Explain.

When hot-air furnaces are used to /s8d9 ml dy3rmheat a house, why is it important that there be a vent for air to returnd/l389sy rd mm to the furnace? What happens if this vent is blocked by a bookcase?

Ceiling fans are sometimes reversible, so that they drive the air dow8 r3o ,vytn8e6isnu2hrx3/p vn in one season and pull it up in another season. Which way 8is3 3,8 xrn /ytrnpvehu2o6v should you set the fan for summer? For winter?

Down sleeping bags and parkas are often spevz7 b(9sjt f2jcified as so many inches or centimeters of loft, the actual thickness of the gafjs t92vb7j z(rment when it is fluffed up. Explain.

Microprocessor chips have a “heat sink” glu fucvn -vzhrq 010**bxk8c7zhed on top that looks like a series of fins. Why is it sha k7vx h c-cnhv*zz800q*u1rbfped like that?

Sea breezes are often enc crt 0k+;bu2d2auda88w )zxeaountered 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 than that of the nearbyu;z0 u+baa28d a kcre)8xwt2d water.

The floor of a house on a foundatc0 lyfq 5)0;c4i 43uhaxqin3ryno. wx ion under which the air can flow is often cooler than a floor that rests directly on the l. 43qcrifn;a hxo0un y )0c3iyq45xwground (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 read g :jaudhbsnt2 -l i.*)6*-ceb tyfu(yings are always taken with the thermometer in the sha*lt.-j: u-)ic*snub2 hgyft6ba (ydede.

A premature baby in an incubator can be dangerously cooled even/) )gndgv .pgktp1x /d when the air temperature in the incubator td1/v.np)g xg/dp k)g is warm. Explain.

Why is the liner of a thermos bottm2fkrvtz(12ids1g ( ele silvered (Fig. 14–15), and why does it have a vacuum between itrs2 g f1kze (mdt(vi21s two walls?

Imagine you have a wall that i -vti- qr)d78zf)jcp1k 71hpayy0 livs very well insulated — it has a very high thermal resistan8hrqtz)1vp f1y 0iv-lp7cy )jd-ika7 ce, $R_1$ 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-jh;+gi k 3fpefy,kl9 following processes: (1) ventilation around edges; (2) through the frame, particularly if it is metal; (3) through the glass panes; and (4) radiip9fkh3 y f kg+e;l-,jation. (a) For the first three, what is (are) the mechanism(s): conduction, convection, or radiation? (b) Heavy curtains reduce which of these heat losses? Explain in detail.

A piece of wood lying in the Sun absorbs more heat than a p eqtorqo /f )m vmxbte4).l)62sr* rc(iece of shiny metal. Yet the wood feels less hot than the metal when you pick it up. Expqqm tore*c t)/rx l(o6r2 b.mf)se)4 vlain.

The Earth cools off at night much more quickly whl.:z vulka2 k1en the weather is clear than when clou 1u l:.lavzk2kdy. Why?

An “emergency blanket” is a thin shiny (metal coated) plastvz md3 lhf48c+w72welic foil. Explain how it can help to keep an immobile perhvz4mw+ 87cd fll 3e2wson warm.

Explain why cities situated by the ocean eqa-h 2/qifbom:znd4)ur u+z1)ly/ul wvi9* tend to have less extreme temperatures tyzv 2lih1 )ol)we:nr+q4 - q/m afuu u/i9bz*dhan inland cities at the same latitude.

  How much heat (in joules) is required to raisv(wk+xkgd1 mk y049mde the temperature of 30.0 kg of water (1+wx dkyk4 m9dvmgk0from 15 ${}^{\circ }C$ to 95 ${}^{\circ }C$ ?    $\times {10}^{7}J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that .2j0zkif+ v kr, dvk*cis initially at 10.0 fk0d*kijvc2,vzr . +k ${}^{\circ }C$ ?    ${}^{\circ }C$

  An average active peovxxvd 4x01v 76:hz,.h qwdb27 p aurvrson consumes about 2500 Cal a day.
(a) What is this in joules?   $\times {10}^{7}J$
(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) io b7rp49 a)1m6kscegzs a unit of heat in the British system of units. One Btu is defined as the heat needed to raise 1 lb of water by 1smag9p 71 c)bezr6o 4k F ${}^{\circ }$ . Show that
1Btu = 0.252kcal=1055J

  A water heater can generg)1tfy /bdqd 8q7 if)p,vq3mj ate $32,000kJ/h$ How much water can it heat from 15 ${}^{\circ }C$ to 50 ${}^{\circ }C$ per hour?    kg/h

  A small immersion heater is rated at 350 W. Estimate how long it 3yns *(y)k.g yl9 nnsswill take to heat a cup of soup (assume this is 250 mL of water) nnys()slgyk 3s n.y9 *from 20${}^{\circ }C$ to 60${}^{\circ }C$ .    min

  How many kilocalories are generate- e0muf,, )xkwf joyn w5c44gv:ma0ppd when the brakes are used to bring a 1200-kg c- mma0p,xjf cf 4 0, nwukopv4e5y)g:war to rest from a speed of $95km/h$ ?    kcal

  An automobile cooling system holds 16 L of wic/t10fr2 t-w4fdq j7rgrp c.ater. How much heat does it absorb i-q0 pdrr.7j4/1tcgcw ir2 fftf its temperature rises from 20${}^{\circ }C$ to 90${}^{\circ }C$?    $\times {10}^{6}J$

  What is the specific heat of a metal sug6u(bsl6d8 p8aus ) /y 2u7g ldwh5godbstance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 5gu8agduh (ogly2wd u p 7d/ls 86)sb618.0${}^{\circ }C$ to 31.5${}^{\circ }C$ ?    $J/kg\cdot C^{\circ }$

  Samples of copper, aluminum, and water experience the9 agpr3u)bt7t same temperature rise when they absorb the sam pr37buttag 9)e amount of heat. What is the ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_{2}O}$ =    :    :   

  A 35-g glass thermometi4m b/3kp dd jamje28:er 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?$T_{i{H}_{2}O}$ =    ${}^{\circ }C$

  What will be the equilibrium temperature w 3c6oeo tq+uo(fbk:* s(nk+hg hen 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 (mass = rpq g;/xr,avl)j eab) ye*6e-$0.4kg$) 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 substan*xewz3p s4tf0ce is 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 0.75 L of water initd4nqsm hq4z1d-gh 3qvqlqv)rrp *8z l-.d*i2ially at2iq3dh4l*qzv - qz-hrg q dd)8r4q*sp .mnlv1 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 cg r1+nzroc*72d gs0plt.q ck/ ontent of 75 g of candy from the following measurements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an alk20c r/tclgpdr.s7zq+* ong 1 uminum 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 okx5 k4ux 8qhk)f 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 ha v:pv8;;y:yy s kagos)s a speed of $6.5m/s$ 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 dm 0(y-d m+ /b3pog/eejqeetv, efined as the amount of heat needed to raise its,mby+-ejq (/met3dp0vg eoe / temperature by 1 $C^{\circ }$ . Thus, to raise the temperature by $\mathrm{\Delta }T$ requires heat Q given by
$Q=C\mathrm{\Delta }T$
(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?    $\times {10}^{3}J/C^{\circ }$
(c) Of 25 kg of water?   $\times {10}^{5}J/C^{\circ }$

  How much heat is needed to melt 16.50 kg r3cgxc-m s15jzmgp s8ox/,e s760 xpzof silver that is initially at 20${}^{\circ }C$?    $\times {10}^{6}J$

  A 0.095-kg aluminium sphere is dropped from the roof ot)xegm4l,fc q9 dy(6of a 45-m-high building. If 65% of the thermal e69cy otxlq )4f,(gdm 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 180 kcal of heat in 30 min by evnh for 36;jbd*aporation of water from the*6d;r3j ohbnf skin. How much water has been lost?    kg

  If $2.80\times {10}^{5}J$ 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 7hse9/y1sis s g1a6bu of liquid nitrogen. How much nitrogen eiau s eh /791ybgss61svaporates if it is at its boiling point of 77 K and has a latent heat of vaporization of $200kJ/kg$ 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 yj, ;t4uq(idxat -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?    $\times {10}^{-3}$ kg

  An iron boiler of mass 230 kg contai3*z mf-hl;0xwawdy ;ins 830 kg of water at 18${}^{\circ }C$. A heater supplies energy at the rate of $52,000kJ/h$ 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, -did.ax (zo;dy /md;u a bicyclist consumes 8.0 L of water over the span of four hours. Making the approximation that all of du;-z.ad;dxd i(o/y mthe cyclist’s energy goes into evaporating this water as sweat, how much energy in kcal did the rider use during the ride? (Since the efficiency of the rider is only about 20%, most of the energy consumed does go to heat, so our approximation is not far off.)    kcal

  What mass of steam at 100co -hyf( 6r ,v+l3bot6j(qjz*x a4tzo${}^{\circ }C$ 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 mercury98mf ;lu 6w-/vlt wwgj is $138J/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${}^{\circ }C$ .    $\times {10}^4$ J/kg

  A 70-g bullet travelingnc6(l 8fz6ur;qcob88rva/ wy at $250m/s$ 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 movingm9lt/3nr puu xtxz9,0 at $6.4m/s$ 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 +-e; po(x-l: veqixdoforensic investigator notes that the 8.2-g lead bullet that was stopped in aqd:xo;i-elpovx e+ -( 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-lo9ysxxrfy kta a(v((3 9ng 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 conduction in Exam/ 2/v1fxzmxuq:axrf * ple 14–10, assuming that there are strong gusty winds and the externa1zr x/*2qmx xvf/ :uafl temperature is -5${}^{\circ }C$   $\times {10}^4$ W

  (a) How much power is radiated by a tungstefu6:c yipn+n9p4c o7t n 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 sknh39rq/4hp f d kb7u5zqaf3v/in. Suppose 200 W of heat flows by conduction from the blood capillaries beneath the skin to the body’s surface area f dk7 quh3qza9 3n/bpv5f4hr/of $1.5m^2$ If the temperature difference is 0.50 $C^{\circ }$ , estimate the average distance of capillaries below the skin surface.    $\times {10}^{-4}$ m

  Two rooms, each a cube 4.0 m p93vu bu83wb2mgup/n x er side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, thgp89uwxbb 3 3 u/umvn2e 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 tg /*h kyekr8;wo melt a block of ice at 0${}^{\circ }C$ with a flat horizontal area $1.0m^2$ 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 .qq j:h3 v/ictqo,s* jcross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace maintained at a constant temperature otiq 3j /.,hqjoc*sq v:f 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 ofkh yb8c*ks (on 7m0/which the whole Earth receives energy from so fb no0*ck/m(87y khthe Sun.    $\times {10}^{17}$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 disam +hp0qvky5.t0) x yisipated 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 pa.yki5+y vh )x0t0 qmthe inner and outer surfaces of the glass?   ${}^{\circ }C$

  Suppose the insulating qualities of the wall of a house come mainly from a 4sb8ivb4 fkr;3(stbz ;.0-in. layer of brick and an R-19 layer of insulation, as shown in Fig. 14–19. What isb(f3;kv; tz 8birbss4 the total rate of heat loss through such a wall, if its total area is $240f{t}^2$ and the temperature difference across it is 12 $F^{\circ }$?    Btu/h

A double-glazed window has two panes of glass separated by an air stq(kfnu+gbz 0g(, xq 4pace, Fig. 14–20. (a) Show that the qgz,(( q4f+0nk bgutx rate of heat flow 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 it take 11.0 kg of ice at 0e;,m0 c3n*bz d zmxz1y${}^{\circ }C$ to melt when it is placed in a carefully sealed Styrofoam ice chest of dimensions $25cm\times 35cm\times 55cm$ 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${}^{\circ }C$.    $\times {10}^4$s

  A soft-drink can conhe.nv .hfj0nfn3.ao -tains 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 $30MJ/kg$ when it is burned, how much coal would be needed to heat a house that requires $2.0\times {10}^{5}MJ$ for the whole winter? Assume that 30% of the heat is lost up the chimney.    kg

  To get an idea of howxx h+enf /g(p6 much thermal energy is 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. (Approximatx f(+ hepg6nx/e the ocean water as pure water for this estimate.)    $\times {10}^{15}J$

  A 15-g lead bullet is tested.oz4 8hbx:rqq by 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 haz q:x.r8qhob 4s been reached, the system has a temperature rise measured as 0.020 $C^{\circ }$. Estimate the entering speed of the bullet.    m/s

  (a) Find the total power radiated into space by the Sun, assuming it to beawikj ph (q+o2- ual+/-ehta h)uk*+b a perfe e ak- h2ul-p*hwb ++kia)qo/ht(ua +jct emitter at $T=5500K$ The Sun’s radius is $7.0\times {10}^{8}m$    $\times {10}^{26}W$
(b) From this, determine the power per unit area arriving at the Earth, $1.5\times {10}^{11}m$ away (Fig. 14–21).    $\times {10}^{3}W/m^2$

  During light activity, a 70-kg person may :9 xi r; /uid5n6jaejrgenerate $200kcal/h$ 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 ilsuwm )8:ln.vertical height of 140 m before striking the ground. Estimate the temperature rise of the rock if sl)m8ul n.wi:50% of the heat generated remains in the rock.    $C^{\circ }$

  A 2.3-kg lead ball is dropped0q m g qe):0/yc4ejczj into a 2.5-L insulated pail of water initially at 20.0 0q4j ecyec:/mzg)jq0${}^{\circ }C$. 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 asj ka8:6ksb8m goose down jacket 3.5 cm thick with total surface area ks86a8bs: kmj $1.2m^2$ 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 zhd+w kg(d(sxo i2/ )hof about $950kcal/h$ 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 itgvwdwl1 7 dq:y z+9a/nterior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the ygtv+ :w/9alw1dzdq7 skin is at 34${}^{\circ }C$ and the interior at 37${}^{\circ }C$, and that the surface area is $1.5m^2$ 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 (asw 8a l2g i(y8gpnb3r ,)-jtiwtsume conductivity of air) and a 3atg -i 2nylg(8bwt,r)wpi8jrea $410m^2$ a roof of wood 6.5 cm thick and area $280m^2$ and uncovered windows 0.65 cm thick and total area $33m^2$
(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${}^{\circ }C$    $\times {10}^5$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 $750m^3$    $\times {10}^8$J
(c) If natural gas costs 0.080 dollars per kilogram and its heat of combustion is $5.4\times {10}^{7}J/kg$ 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 $0.24kcal/kg$$\cdot C$.    dollars

  A 15-g lead bullet traveling a lot0cr: 0a:dat $220m/s$ passes through a thin wall and emerges at a speed of $160m/s$ 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 $40c{m}^2$ and mass $4.5\times {10}^{-4}kg$ directly faces the Sun on a clear day. The leaf has an emissivity of 0.85 and a specific heat of $0.80kcal/kg\cdot K$.
(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 f2(/c5tob rkq (a) in Problem 58, take into account radiation from the leaf to calculate how much water must be trafbc5/rqo 2( tknspired (evaporated) by the leaf per hour to maintain a temperature of 35${}^{\circ }C$.    g/h

  An iron meteorite melts when it enters the Earthxtf 4v/foe oplb843 6p’s atmosphere. If its initial temperature wbot/pox8pv4 f3 6f le4as -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 with xoe /2-g 7bxxp)mv:(3mvzrobin the Earth’s crust increases about 1.0 C${}^{\circ }$ for each 30 m of depth. The thermal conductivity of the crust is $0.80W/C^{\circ }\cdot m$
(a) Determine the heat transferred from the interior to the surface for the entire Earth in 1 day.    $\times {10}^{18}J$
(b) Compare this heat to the amount of energy incident on the Earth in 1 day due to radiation from the Sun.$Q_{Sun}$ =    $\times {10}^4{Q}_{interior}$

  In a typical game of squashw zs4 :2,p; punu: ;tk9zf mz1hrwh,on (Fig. 14–22), two people hit a soft rubber ball at a wall until they are about to drop due to dehydration hpm ,p,;r:4unwzf;ws:oht9nk u 1z2z and exhaustion. Assume that the ball hits the wall at a velocity of $22m/s$ and bounces back with a velocity of $12m/s$ 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 $1200J/kg$$\cdot C$)    $C^{\circ }$

What will be the final result when equal masses of rydg .u8 oz3i* +kwrmzec; nzvy2g8(6ice 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 radiat dumk2s -rhtvy(lz1,7ion at a rate of about 200 W. Estimate how lovz tky2d7r-1l(u,m hs ng 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 “noo9ir9vs t+ j4o hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with w+vt9rsio o4 9jater 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 glassdvhfcbmyr*b2)hq;ca e 3) z52 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.    ${}^{\circ }C$