E-PolyLearning

41. The following data pertains to a hollow cylinder and a hollow sphere made of same material and having the same temperature drop over the wall thickness

Inside radius = 0.1 m and outside surface area = 1 square meter

If the outside radius for both the geometrics is same, calculate the ratio of heat flow in the cylinder to that of sphere?
a. 0.056
b. 2.345
c. 1.756
d. 3.543
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Answer: (c).1.756

42. “All the factors relating to geometry of the sections are grouped together into a multiple constant called the shape factor” True or false
a. True
b. False
c. May be
d. Can't say
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Answer: (b).False

43. Shape factor for plane wall is equal to
a. A/δ
b. 2A/δ
c. 3A/δ
d. 4A/δ
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Answer: (a).A/δ

44. For a prescribed temperature difference, bodies with the same shape factor will allow heat conduction proportional to
a. k/2
b. 2k
c. k
d. k/4
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Answer: (c).k

45. Shape factor for cylinder is
a. 6 π l/log e (r₂/r₁)
b. 4 π l/log e (r₂/r₁)
c. π l/log e (r₂/r₁)
d. 2 π l/log e (r₂/r₁)
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Answer: (d).2 π l/log e (r₂/r₁)