Consider a spherical shell of inner radius r 1 and outer radius r 2 whose thermal conductivity varies linearly in a specified temperature range as k ( T ) = k 0 ( 1 + β T ) , where k 0 and β are two specified constants. The inner surface of the shell is maintained at a constant temperature of T 1 , while the outer surface is maintained at T 2 . Assuming steady one-dimensional heat transfer, obtain a relation for (a) the heat transfer rate through the shell and (b) the temperature distribution T(r) in the shell.
Consider a spherical shell of inner radius r 1 and outer radius r 2 whose thermal conductivity varies linearly in a specified temperature range as k ( T ) = k 0 ( 1 + β T ) , where k 0 and β are two specified constants. The inner surface of the shell is maintained at a constant temperature of T 1 , while the outer surface is maintained at T 2 . Assuming steady one-dimensional heat transfer, obtain a relation for (a) the heat transfer rate through the shell and (b) the temperature distribution T(r) in the shell.
Solution Summary: The author explains the heat transfer rate through the shell, the thermal conductivity, and the coefficient of the temperature distribution.
Consider a spherical shell of inner radius r1 and outer radius r2 whose thermal conductivity varies linearly in a specified temperature range as
k
(
T
)
=
k
0
(
1
+
β
T
)
,
where k
0
and
β
are two specified constants. The inner surface of the shell is maintained at a constant temperature of T1, while the outer surface is maintained at T2. Assuming steady one-dimensional heat transfer, obtain a relation for (a) the heat transfer rate through the shell and (b) the temperature distribution T(r) in the shell.
Problem 6 (Optional, extra 6 points)
150 mm
150 mm
120 mm
80 mm
60 mm
PROBLEM 18.103
A 2.5 kg homogeneous disk of radius 80 mm rotates with an
angular velocity ₁ with respect to arm ABC, which is welded
to a shaft DCE rotating as shown at the constant rate
w212 rad/s. Friction in the bearing at A causes ₁ to
decrease at the rate of 15 rad/s². Determine the dynamic
reactions at D and E at a time when ₁ has decreased to
50 rad/s.
Answer:
5=-22.01 +26.8} N
E=-21.2-5.20Ĵ N
Problem 1.
Two uniform rods AB and CE, each of weight 3 lb and length 2 ft, are welded to each other at their
midpoints. Knowing that this assembly has an angular velocity of constant magnitude c = 12 rad/s,
determine:
(1). the magnitude and direction of the angular momentum HD of the assembly about D.
(2). the dynamic reactions (ignore mg) at the bearings at A and B.
9 in.
3 in.
03
9 in.
3 in.
Answers: HD = 0.162 i +0.184 j slug-ft²/s
HG = 2.21 k
Ay =-1.1 lb; Az = 0; By = 1.1 lb; B₂ = 0.
Problem 5 (Optional, extra 6 points)
A 6-lb homogeneous disk of radius 3 in. spins as shown at the constant rate w₁ = 60 rad/s. The disk
is supported by the fork-ended rod AB, which is welded to the vertical shaft CBD. The system is
at rest when a couple Mo= (0.25ft-lb)j is applied to the shaft for 2 s and then removed. Determine
the dynamic reactions at C and D before and after the couple has been removed at 2 s.
4 in.
C
B
Mo
5 in
4 in.
Note: 2 rotating around CD induced by Mo is NOT
constant before Mo is removed.
and ₂ (two
unknowns) are related by the equation: ₂ =0+ w₂t
3 in.
Partial Answer (after Mo has been removed):
C-7.81+7.43k lb
D -7.81 7.43 lb
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