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PROBLEM B.25
A 2-mm thick piece of sheet steel is cut and bent into the machine
component shown. Knowing that the density of steel is 7850 kg/m3,
determine the mass moment of inertia of the component with
respect to each of the coordinate axes.
PROBLEM B.25 (Continued)
Panel 2:
z
PROBLEM B.26
A 2-mm thick piece of sheet steel is cut and bent into the
machine component shown. Knowing that the density of steel is
7850 kg/m
3
, determine the mass moment of inertia of the
component with respect to each of the coordinate axes.
PROBLEM B.26 (Continued)
123
() () ()
yy y y
II I I
22
4
(0.003880 0.064017)] kg m
2
2
(0.196160 0.044572 0.067897) kg m
2
0.308629 kg m
or
32
309 10 kg m
y
I
123
2
() () ()
(2.14305 kg)(0.35 m) (2.14305 kg) m
zz z z
II I I
4
or
32
154.4 10 kg m
z
I
PROBLEM B.27
A subassembly for a model airplane is fabricated from three pieces of 1.5-
mm plywood. Neglecting the mass of the adhesive used to assemble the
three pieces, determine the mass moment of inertia of the subassembly
with respect to each of the coordinate axes. (The density of the plywood
is
3
780 kg/m .)
PROBLEM B.27 (Continued)
123
2
() () ()
18 3
yy y y
II I I
1(21.0600 10 kg)[(0.3) (0.12) ] m
62
[(105.300 210.600) (122.148 244.296)
(47.637)] 10 kg m
62
(315.900 366.444 47.637) 10 kg m
62
PROBLEM B.28
A section of sheet steel 0.03 in. thick is cut and bent into the
sheet metal machine component shown. Determine the mass
moment of inertia of the component with respect to each of the
coordinate axes. (The specific weight of steel is 490 lb/ft3.)
Copyright © McGraw-Hill Education. Permission required for reproduction or display.
PROBLEM B.28 (Continued)
Plate 2 in x-z plane:
Note: By Eqn. 9.38,
66
'
55.728 10 396.29 10
yuv
III
2
2
6 2
761.62 10 lb ft s
y
y
I
Finally, total for both plates 1 and 2 gives,
12
66
594.43 10 761.62 10
yy y
III
32
PROBLEM B.29
A framing anchor is formed of 0.05-in.-thick galvanized steel. Determine the
mass moment of inertia of the anchor with respect to each of the coordinate
axes. (The specific weight of galvanized steel is
3
470 lb/ft .)
PROBLEM B.29 (Continued)
62 2 22
1(2006.14 10 lb s /ft)[(4.75) (2) ] in
18
[(23.578 70.735) (0.550 82.490)
x
123
62 2
22
() () ()
1(3325.97 10 lb s /ft)(2.25 in.)
12
212 in.
yy y y
II I I
62 2 22
1(950.28 10 lb s /ft)[(2.25) (1) ] in
12
22
62 2 2
18
11 ft
62
[(9.744 29.232) (3.334 10.002)
(3.096 76.720)] 10 lb ft s
