4. The drawing shows a composite slabconsisting of three materials throughwhich heat is conducted from left to right.65 °C45 °C30 °C25 °CThe materials have identical thicknessesand cross-sectional areas. Rank the ma-terials according to their thermal conduc-tivities, largest first. (a) k,, k,, kz (b) k̟, k3, kz(c) k, kj, kz (d) k2, k3, k¡ (e) kz, k2, kį

The temperature difference through slab 1 (∆T1)=65-45=20 oC The temperature difference through slab…

Answered: 4. The drawing shows a composite slab…

College Physics

10th Edition

ISBN:9781285737027

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter11: Energy In Thermal Processes

Section: Chapter Questions

Problem 40P: The thermal conductivities of human tissues vary greatly. Fat and skin have conductivities of about...

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The thermal conductivities of human tissues vary greatly. Fat and skin have conductivities of about 0.20 W/m K and 0.020 W/m K, respectively, while other tissues inside the body have conductivities of about 0.50 W/m K. Assume that between the core region of the body and the skin sin face lies a skin layer of 1.0 mm, fat layer of 0.50 cm, and 3.2 cm of other tissues. (a) Find the R-factor for each of these layers, and the equivalent R-factor for all layers taken together, retaining two digits. (b) Find the rate of energy loss when the core temperature is 37C and the exterior temperature is 0C. Assume that both a protective layer of clothing and an insulating layer of unmoving air a absent, and a body area of 2.0 m2.
What mass of water at 25.0C must be allowed to conic to thermal equilibrium with a 1.85-kg cube of aluminum initially at 1.50 102C to lower the temperature of the aluminum to 65.0C? Assume any water turned to steam subsequently recondenses.
3. Two medal bars X and Y have the lengths of TO cm and 30 cm.Both have the same croos sectional area. At one end of the metal X, heat supplied from koiling warler at 0°C.Both metas are well-insulated. The remperature ad the junction is 15°C. at 100 °C and one and of the metal Yisplaced in me Hing Ice Calculate the CAssume the heat flow 1s steady and no energy radio of themal conductivity between metal X and Y. 1s lost do the surroundings)
A cylindrical metal boiler of radius 10 cm and thickness 3.14 cm is filled with water and placed on an electric heater. If the water boils at the rate of 50 g s', estimate the temperature of the fila- ment. Thermal conductivity of metal 102 w m K- and latent heat of vaporisation = 2.26 x 10° J g'. = 1.13 × %3D
Calculate the rate of heat conduction out of the human body, assuming that the core internal temperature is 37°C, the, the skin temperature is 35°C, thickness of the tissues between averages 1 cm, and the surface area is 1.6 m². Assume thermal conductivity of the tissue is 0.2 W/m/K) ○ A. 46.0 W O B. 96.4 W ○ C. 64 W ○ D. It cannot be calculated as the type of dress worn is unknown. ○ E. -90 W
A solid concrete wall. (k = 0.0012) is 30 cm thick. If the inner. surface is :2O°C and the outer is o° C, find the temperature in the wall. as.a function of the distance from the outer surface and det ermine the heat los per.day through a square. meter.
5. Heat is conducted through a slab composed of parallel layers of different conductivities, 0.0050 and 0.0025 cal/cm2 -sec-C/cm and thickness 0.36 and 0.48 cm, respectively. The temperatures of the outer faces of the slab are 96 and 8C, find the temperature of the interface Pls include fbd
Question 6 A steel bar 5 cm long is welded end to end to a copper bar 4 cm long. Each bar has a square cross section 2.00 cm on a side. The free end of the steel with a temprature at 49 °C, and the free end of the cooper bar is at 19 °C. Find the total rate of heat flow in (W)? (ksteel =50.2 W/K.m and kcopper =385 W/K.m ) (Answer in one decimal places) Material having thermal conductivity k Area A Steel Copper
3 3. Concrete sidewalks are always laid in sections, with gaps between each section. For example, the figure shows five identical 5.80-m sections, the outer two of which are against immovable walls. The four identical gaps between the sections are provided so that thermal expansion will not create the thermal stress that could lead to cracks. What is the minimum gap width necessary to account for an increase in temperature of 40 °C? E 20 F3 000 000 F4 % 5 cm MAA F5 C 6: MacBook Air Gap Y & 7 T BROMU F7 * 00 8 DII F8 ( 9 DD F9 O F10 Eli F12
| ASKLEINESEN At what rate (W) is heat loss through a 1.23 m by 1.76 m glass window pane that is 0.620 cm thick when the inside temperature is 20.3 °C and the outside temperature is 4.1 °C? Heat Loss = Number W At what rate (W) is heat loss through a 1.23 m by 1.76 m glass window pane that is 0.620 cm thick when the inside temperature is 20.3°C and the outside temperature is 4.1°C
For item 42: Table D2 Determination of Specific Heat of a Metal Initial mass of metal, mm (g) Initial temperature of metal, Tm,0 (°C) Initial mass of water, mw (g) Initial temperature ofwater, Tw,0 (°C) Final Temperature of mixture, T,(°C) Experimental Specific Heat cal of metal Cexp Actual Specific Heat of cal metal Cact g.Cº. Percentage Error Copper 30 42.) 110 43.) 125 20 21.94 0.9195 % For Item 42: choices for number 42 0.9180 0.9436 0.9513 0.8154 0.8354 For item 43: choices for number 43 0.17 O 0.16 0.15 0.18 0.19
A steel bar 2 cm long is welded end to end to a copper bar 7 cm long. Each bar has a square cross section 2.00 cm on a side. The free end of the steel with a temprature at 63 °C, and the free end of the cooper bar is at 16 °C. Find the total rate of heat flow in (W)? (keteel -50.2 W/K.m and kcopper -385 W/K.m) (Answer in one decimal places) Materal having thermal conductivity k Area A Steel Copper

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