Question 1 of 14 - ll View Policies Current Attempt in Progress The drawing shows a composite slab consisting of three materials through which heat is conducted from left to right. The materials have identical thicknesses and cross sectional areas. Rank the materials according to their thermal conductivities, largest rst. 65 C 45 C 30 C 25 C O k1,k3,k2 O k2,l -/1 E Next question Question 4 of 14 _ ,1 ;: View Policies Current Attempt in Progress Two objects are maintained at constant temperatures, one hot and one cold. Two identical bars can be attached end to end, as in part a of the drawing, or one on top ofthe other, as in part b. When either of these arrangements is placed between the hot and the cold objects for the same amount of time, heat Q ows from left to right. Find the ratio Qa/Qb. Qa/Qb= Number n Units v Question 6 of 14 -/1 E View Policies Current Attempt in Progress The block in the drawing has dimensions L0X2LOX3L0,where L0 =O.5 m. The block has a thermal conductivity of 100 J/(s-m-C"). In drawings A, B, and C, heat is conducted through the block in three different directions; in each case the temperature of the warmer surface is 30 \"C and that of the cooler surface is 18 \"C Determine the heat that ows in 8 s for each case. Pmblem 6 C (a) Q = v lb) Q = v Question 7 of 14 > - /1 ... View Policies Current Attempt in Progress A closed box is filled with dry ice at a temperature of -85.2 C, while the outside temperature is 29.7 C. The box is cubical, measuring 0.389 m on a side, and the thickness of the walls is 4.44 x 102 m. In one day, 3.82 x 10 J of heat is conducted through the six walls. Find the thermal conductivity of the material from which the box is made. Number UnitsQuestion 8 of 14 -/1 E View Policies Current Attempt in Progress Review Conceptual Example 5 before attempting this problem.To illustrate the effect of ice on the aluminum cooling plate, consider the drawing shown here and the data that it contains. Ignore any limitaions due to signicant gures. How much heat per second per square meter is conducted through the ice-aluminum combination and through the aluminum by itself? Aluminum ICE 10.0 C 25.0 \"'0 440.0050 m'r? 0.0015 m un'm...' -...-... O combination: 2400000 J/(s m2), aluminum only: 2400000 J/(s m2) 0 combination: 6580 Ms m2}, aluminum only: 2400000 J/(s m2) 0 combination: 6580 J/(s m2}, aluminum only: 6580 J/(s m2) 0 combination: 2400000 J/(s m2), aluminum only: 6580 Ms m2) Question 9 of 14 I "I-.. _\\ III 0.0 View Policies Current Attempt in Progress Two pots are identical except that the at bottom of one is aluminum, whereas that of the other is copper. Water in these pots is boiling away at 100.0 "C at the same rate. The temperature of the heating element on which the aluminum bottom is sitting is 168 "C. Assume that heat enters the water only through the bottoms of the pots and nd the temperature of the heating element on which the copper bottom rests. TCu= n v Question \"ID of 14 -/i E View Policies Next question Current Attempt in Progress Light bulb 1 operates with a lament temperature of 3000 K, whereas light bulb 2 has a lament temperature of 1900 K. Both laments have the same emissivity, and both bulbs radiate the same power. Find the ratio A1/A2 of the lament areas of the bulbs. A1/A2= Number l Units v 000 I 5-... _\\ 0.. Question 11 of \"l4 View Policies Current Attempt in Progress Multiple-Concept Example 8 reviews the approach that is used in problems such as this. A person eats a dessert that contains 190 Calories. (This "Calorie" unit, with a capital C, is the one used by nutritionists; 1 Calorie = 4186 J. See Section 12.7.] The skin temperature of the person is 37 OC and that of her environment is 20 C'C. The emissivity of her skin is 0.68 and its surface area is 1.2 m2. How many hours would it take her to emit a net radiant energy from her body that is equal to the energy contained in this dessert? Heal from enwronmenl \\ 1,0 Heat from person M; 'I J \\ Number n Units V Question 12 of 14 > - /1 ... View Policies Current Attempt in Progress Sirius B is a white star that has a surface temperature (in kelvins) that is four times that of our sun. Sirius B radiates only 0.040 times the power radiated by the sun. Our sun has a radius of 6.96 x 10 m. Assuming that Sirius B has the same emissivity as the sun, find the radius of Sirius B. RSB = iQuestion '|3 of 14 -/1 E View Policies Current Attempt in Progress Asolid sphere has a temperature of 533 K. The sphere is melted down and recast into a cube that has the same emissivity and emits the same radiant power as the sphere. What is the cube's temperature in kelvins? Number n Units v Question 14 0f'l4