What happens to the work done when a j7lvi9 6z 38aqb *amzztar of orange juice is vigorously shaken?

When a hot object warms a cooler object, does temperature flo h(zhqa1:lrf 1w between them? Are lfq1:ahzr( h1 the temperature changes of the two objects equal?

(a) If two objects of different temperatures are placed in contact, will heat nqexxrcc dj b0540 a,+gaturally flow from the object 5jx ,0adq 0gc4xr bec+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 b g*o3b nsy1vff9-ii1but the temperature may drop below freezing a few times in the winter, the destruction of sensitive plants 1fi*9v31s-ib ofngybdue 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 pary pmvt0g8:u 5k-ehl6vticularly good for heating systee:0k 8tm5pu-l6v ghyvms (that is, hot-water radiators).

Why does water in a metal canteen stay cooler if the pf4 zdh4v4i.rcloth jacket surrounding the canteen is r. 4f44zi phvdkept moist?

Explain why burns caused by steam on the lv)b+ifhc3u2;0zbo p skin are often more severe than burns caused by water a +fvb;c 3)ouzphl02ibt 100 $^{\circ} C$ .

Explain why water cools (its temperature drops) when it eb c64wzq;x60 mycmz1vb0qp0p vaporates, using the concepts of latent heat and intern0y64c vq16 zpwb0x; z0 qcmbpmal energy.

Will potatoes cook faster if the water is boilingm8t5 q:vwbzn+oj0m ; g faster?

Does an ordinary electric fan cool the air? Why or why not? If not, why d r+5hbj40r6hfuua :,hsz ab- use it?

Very high in the Earth’s atmz2 niuwp51bf o-if,o )osphere, 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 survijqz(xn:1 ,o si t/klkk)y-jp 5ved by covering themselves with snow. Why wou/yjlpx n)k :(ksoj 5qikt -1,zld they do that?

Why is wet sand at the beach cooler to walk on than dry sa-hzk f,p,-hzv l,jqrxh.p vqm yk 5(.4nd?

If you hear that an object has “high heat conti ;ktvz;*a k+aent,” does that mean that its temperature is a ;;tz*+ia kvkhigh? Explain.

When hot-air furnaces are used to hej0wv+rl(t ndp) euc5tc 5-q k6at a house, why is it important that there be a vent for air to return to the furnace? What happens if this vent is blocked by a bookcase?-n6 etc0l 5wt5r) pk (udv+qjc

Ceiling fans are sometimes reversible, so that they drive the air))l7 ecig; nn w:y7 fjtaqsy1s4 7/xhl down in one season and pull it up in another season. W gli)nhs)ncqs14ftw/ 7;a:y7elj7x y hich way should you set the fan for summer? For winter?

Down sleeping bags and parkas are often specified as so many inches or jq:7.hv2 g1lwhvodj (centimeters of loft, the actual thickness of the garment when it is fluffed up. .v7(h jqvljw21:ohdg Explain.

Microprocessor chips have a “heat sink” glued on top that looks like a u1+l/elzcfa ; 4mdiy 0series of fins. Why is it shaped like that?f0 ld yia4m+c ze/1u;l

Sea breezes are often encou4hj *dwjt r+9b -5i:1m ovjmjlntered on sunny days at the shore of a large body of water. Explain in light of the fact that the temperatujido+wr 4vhl:jj15b9-t*m mjre of the land rises more rapidly than that of the nearby water.

The floor of a house on a foundation under whicp1y70hjlhz 4zm-- xur2 mhe6zh the air can flow is often cooler than a floor that rests directly on the ground (such as a concrete slab foun 1yxe z h 2h04mr6huzlj-m7pz-dation). Explain.

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

Explain why air temperature readings are always taken with rja f.*,r5ksd ;hyncb .zg:1s the thermometer in the*r h5 sjysd1rbgn.;k f:za. c, shade.

A premature baby in an incubator can be dangerously cooled eva2 jzw;r/a top7 -f)idxpfc7; en when the air temperature in the incubator is warm. Explai;dpwr-p/2)f 7x ozj7iaaftc;n.

Why is the liner of a thermos bottle silverxjaw(vu7 f0w,0 wew4 led (Fig. 14–15), and why does it have a v 7aww4vwjux(w,l0e f0acuum between its two walls?

Imagine you have a wall tha zgcp 9htnx .xqc72//0txwfk5t is very well insulated — it has a very high thermal resistax7c pnt902twx.gcqk fhx/ z5/ nce, $R_1$ 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 thxj cj7aphhg0,)a ns 6:e 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 which of these heat:7,a0g xjpj 6 h)nsahc losses? Explain in detail.

A piece of wood lying in theynuafwn( n 2(.vv-z tre807qk Sun absorbs more heat than a piece of shiny metal. Yet the wood feels less w7.0vrey- kt((nn2qn ufzva8hot than the metal when you pick it up. Explain.

The Earth cools off at night much more quickly w thkie: (lg11ayb 3x,gln9 ot2hen the weather is clear than when cloudy. Why?ath3y:oet,ikl21 l 9(bn 1ggx

An “emergency blanket” is a thin shiny (metal coated) plastic foil. Expl) - ihx.o+bbybain how it can help to keep an immobile person warb-h+b bo) x.iym.

Explain why cities sit0 6dnc.;l7c1xdcl4: w2 j fjov qc*duguated by the ocean tend to have less extreme temperatures than inland cities at the same latituj;gd oux1vdd6c:l q7fc42 . *ncwcl0jde.

  How much heat (in joules) is required tx.6jm3z8k0vzbl a8 (ump1l b ho raise the temperature of 30.0 kg of water frxkz.38m jl8lauhbm p v(106bzom 15 $^{\circ} C$ to 95 $^{\circ} C$ ?    $ \times10^{7 }\,J$

  To what temperature will 7700 J of heat raise 3.0 kg of water that is initiaizof9 -l c*cu+hi0v9 xlly at 10.0 9ic- 9loxufvz+ i*hc0 $^{\circ} C$ ?    $^{\circ} C$

  An average active person consln i;k kx/-(odc.xc *h5;f btfumes 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 s61ncb0i-g pl0n6xv4,/kr vtb)xt oja ystem of units. Oxapn / 6 -oc14,rxjtgbl6tnb0vki 0 )vne Btu is defined as the heat needed to raise 1 lb of water by 1 F $^{\circ} $ . Show that
1Btu = 0.252kcal=1055J

  A water heater can genek5w:8wfp 8dkrfi-t fz8(2wvk vv (d1yrate $32,000\,kJ/h$ How much water can it heat from 15 $^{\circ} C$ to 50 $^{\circ} C$ per hour?    kg/h

  A small immersion heater is rated atofbk9dh xe8 w)+2e*nn 350 W. Estimate how long it will take to heat a cup of soup (assume this is 250 mL off*no 2nwehdek)b9+8x water) from 20$^{\circ} C$ to 60$^{\circ} C$ .    min

  How many kilocalorie 14d5ytw w82pzg2uqp ks are generated when the brakes are used to bring a 1200-kg car to rest from a speedk 4 w tzq1dpy8uwgp225 of $95\,km/h$ ?    kcal

  An automobile cooling system holds 16 L of water. Howl n59 kjr.oyu0caz 22i much heat does it absorb ilij92yn 0k5.roca z2 uf its temperature rises from 20$^{\circ}C $ to 90$^{\circ} C$?    $ \times10^{ 6}\,J$

  What is the specific heat of a metal subst iei,/q -g x+08dnrr7c+dsplw ance if 135 kJ of heat is needed to raise 5.1 kg of the metal 8/i r +,gx c70sidq+ n-derlwpfrom 18.0$^{\circ}C $ to 31.5$^{\circ} C$ ?    $J/kg\cdot\,C^{\circ} $

  Samples of copper, aluminum, and water experience the same temperature riseh+bb6*t2y zi a when they absorb the same amount of heat. What is t6zb2b a*i y+thhe ratio of their masses? [Hint: See Table 14–1.]$m_{Cu}$ : $m_{Al}$ : $m_{H_2O}$ =    :    :   

  A 35-g glass thermometer reads 2gu ,7qfk i ug:;-qc-ggi73r u bws;;zy1.6$^{\circ} C$ 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 gi5xbb;tx/byo 9( t;o(q9vp.pp(wcw temperature when a 245-g block of copper at 285$^{\circ}C $ is placed in a 145-g aluminum calorimeter cup containing 825 g of water at 12.0$^{\circ} C$ ? $T_{eq}$ =    $^{\circ} C$

  A hot iron horseshoe (mhwy) v95e*3q 4c pfepig8:xs dass = $0.4\,kg$) 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 substanc5iszh7 gql nh /x/ d-wuj6(9qle 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 coffeepo w77 ojs4zl.slt to bring to a boil 0.75 L of water initially at 87z oj 7swl.4ls.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 measu7uciplh +0i 6vrements. A 15-g sample of the candy is allowed to dry before putting it in a bomb calorimeter. The aluminum bomb has a mass of 0.725 kg and is placed in 2.00 kg of water contained in an aluminum calorimeter cup of mass 0.624 kg. The initial temperature of the mixtpc+l670 uvi ihure is 15.0$^{\circ}C $ , and its temperature after ignition is 53.5$^{\circ} C$ .    Cal

  When a 290-g piece of iron a fvx20+p/ ,ihij6mgcqywd hz n:s:u15t 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 hau-h p1z1co,nhmmer 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 ago/1w q th. x jtgduqrx7 ri*7:*j7-vln object is defined as the amount of heat needed to raise its /w* t gj17qrojlxvtx-id* r. gu7h:7qtemperature 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 8-n*ora wyq5y 16.50 kg of silver that is initially at 20$^{\circ} C$?    $ \times10^{6 }\,J$

  A 0.095-kg aluminium sphere is dropped from th/ m 3az;)j ws98 qr+nvq)qwg38h blugfe roof of a 45-m-high building. If 65% of the thermal energy produced when it hits 3q gg ;w/v qzu)a9+bl3r)n8j wqhf8sm 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 mqgs k0 )m7o3gfvg28zoin by evaporation of water from the skin. How much water has bvs8f 073m)gzgk2oq ogeen 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 ; *ft/pl,)us g jauj,scontainer of liquid nitrogen. How much nitrogen evaporates if it is at its boil;, s)utuajgpsj/ f*l ,ing 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 atv 27gyjbq f35psmwg/4 3/nx kb -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.lecshe)7 .ndut j7huy yt/a9;0 ec/ z contains 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 of fouw4he8n 3sxp;/ +t*e+ wz+z xtvz( fzi,ow+hdzr 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 ridere w wwz +v h;oz+z+xi8f3+*dntzpxt( sh,4/ze 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 rjy 9 jwgss094sr4qx)whog8 7100$^{\circ} C$ 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 /ihl sjdz (6u: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 ,tk jw6;c2 l:oaoe0tr $250\,m/s$ 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 moving at olccav6tf w8-c a79o. 0jy h9l$6.4\,m/s$ 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 investigatouz,u4v*f lg:bb5qmt 6 ()vdty r notes that the 8.2-g lead bullet that was stopped in a doorframe,: utbvgmt(f5ld u *y6vb q)4z 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 a;cw r* ,socz*fvfs0: 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 heazka9. lgre/ e-t flow by conduction in Example 14–10, assuming that there are ege.z /k-a9lrstrong gusty winds and the external temperature is -5$^{\circ} C$   $ \times10^{4 }$ W

  (a) How much power is radiated by a tungsten sphere (emissivit8xmr q onrfnujl.(dd3 8 v0od*v8*.osy $e\,=\,0.35$) of radius 22 cm at a temperature of 25$^{\circ} C$ ?    W
(b) If the sphere is enclosed in a room whose walls are kept at -5$^{\circ} C$ what is the net flow rate of energy out of the sphere?    W

  Heat conduction to skin. Suppose 200 W of heat flows by conduction from1z5hg j7b pwl3 the blood capillaries beneath hp1 57bg 3wljzthe 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 4.6 hbsxb ;-tif00 m per side, share a 12-cm-thick brick wall. Because of a number of 100-W lightbulbs in one room, the air 0t xh6bb-;fs iis 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 twlwy57p1 lad0 o 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 rod of the same l *oggz0jvw6l) tr k/:hength and cross-sectional area are attached end to end (Fig. 14–18). The copper end is placed in a furnace mo*gj6wh r/0)zg:vl tk aintained 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 whynovj/o:i2i q + uo1/ 7bwnv4o)9melhole Earth receives energy from the Suhyon/ ojl2)wqn 1:imobi 9/vove+ u74 n.    $ \times10^{17 }$W
(b) Assume the Earth radiates an equal amount back into space (that is, the Earth is in equilibrium). Then, assuming the Earth is a perfect emitter ($e\,=\,1.0$) estimate its average surface temperature.    $^{\circ} C$

  A 100-W lightbulb generates 95 W of heat, which is dissipated through a glass2l3yn6r-tuqikr spug 7 99lh2 bulb that has a radius npl2rl-ygki tu 7396r hs 2uq9of 3.0 cm and is 1.0 mm thick. What is the difference in temperature between the inner and outer surfaces of the glass?   $^{\circ}C $

  Suppose the insulating qualities of the wall of a house comc .l mzdleg2v0k3r vj ./es(1pe mainly from a 4.0-in. layer of brick and an R-19 layer of insulation, a2/cme0(3kzvve p.1s.d jlg lrs 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 panes of glass sepdqbji( zwtmla8en:( okp0q (ft4c8 * .ndt0d3arated by an air space, Fig. 14lz( t:0j34t.(wmdn i0*qkc8qf ot8nda eb(pd –20. (a) Show that the 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) hyci*g* uwv89q3haln+z 8 kv 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 liquidbhr39iegj.,oj8r befap84 0c 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 containexti;0bmqbu:. wg zw5:d in the world’s oceans, estimate the heat liberated when a cube of ocean water, 1 kmmt x ;b05gqu:.zwwbi: on each side, is cooled by 1 K. (Approximate the ocean water as pure water for this estimate.)    $ \times10^{ 15}\,J$

  A 15-g lead bullet is tested by firing it into a fixed blo 2d5m3 ((ur39hlut8anbxf rb; (lfxbi:ohj 4i ck of wood with a mass of 1.05 kg. The block and imbedded bullet together absorb all the heat generated. Aflh9rhtio( ( bxljdab8fn2b;m:35f x4u ru(3 iter 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 the Sun, assuming o 9+abqvce2:)im z2 yca5l4+taw/ lfqit to be a perfect emitter at o/t+ l:5f+ c2izq)wa2mq9 4be vacyla$T\,=\,5500K$ 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 mayz139x0xk* dan6xrzfq 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 heigj2- qpn gv,.jcht of 140 m before striking the ground. Estimate the temperat.gqjjn -vp,2c ure 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.r q rwd0j4+5qta/i2o kisif2 ;5-L insulated pail of water initially at 20.02ra0rqiwo k; si qjtd2/54i+f$^{\circ} C$. 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 uj91 4 58d /sv-4ngablv +pzcl8 3va,egkiswgthick with total surface areadagi s4vvwjk1n5 b+/lv3eca 8,pg zs9-u4gl8 $1.2\,m^2$ 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 me(* pv6eyat5oqtabolism rate of about $950\,kcal/h$ during a race. If the runner has a mass of 55 kg, estimate how much water she would lose to evaporation from the skin for a race that lasts 2.5 h.    kg

  Estimate the rate at which heat can b2sr6o fictues tf qp08/k b1o90iey57e conducted from the interior of the body to the surface. Assume that the thickness of tissue is 4.0 cm, that the i/9et r ffqt0kec5oy6 p1820bsuso 7i 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 wallsams/-qb iafota+0/( vq 0pwa- 17.5 cm thick (assume conductivity of air) and w m/ /a0q +i(0b--aqatspfavoarea $410\,m^2$ 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 travelins7 sbtij3( 7b+kngxgvci6i, 1g 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 xzgu vfw n51xo( m+-m-58, take into account radiation from the leaf to calculate how much water muxgmoxu(5wv- 1n -mz+f st be transpired (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.yoyhw-)srx22 If its initial temperature was r- wyhsx2 2oy)-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 about 1.0 4 *u ;)tzg;ytv fy.nafC$^{\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. 14–2 *e7; .w kq d.zuu1ng7spn7emq2), two people hit a soft rubber ball at a wall until the*;nwg.ee.7q7 zu7 suq1pk ndmy 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 at n g+(hpav kp:yih90q-0$^{\circ} C$ and steam at 100$^{\circ}C $ are mixed together?

  In a cold environment, a person can lose heat by dp/6roo34u90wjgfy:s +nipmconduction and radiation at a rate of about 200 W. Estimate how long it would take for the body tempefo/u49g m0 s6njp i+ywdr o:3prature 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 dishwashi*whj7y84cyh( :vuii2txdp+ f ng, there is “no hot water” left in the 50-gal (185-L) water heater. This suggests that the tank has emptied and refilled with water at yw:(cvx yh8*+ ftid ij472phuroughly 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 5bhz)0qq.)kbhhz9 h ua 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.    $^{\circ} C$