PROBLEM 18.147
Three 25-lb rotor disks are attached to a shaft which rotates
at 720 rpm. Disk A is attached eccentrically so that its mass
center is 1
4in. from the axis of rotation, while disks B and C
are attached so that their mass centers coincide with the axis
of rotation. Where should 2-lb weights be bolted to disks B
and C to balance the system dynamically?
PROBLEM 18.147 (Continued)
Data: 125lb
in. 0.25 in. 12.5
42lb
A
m
rm

PROBLEM 18.148
A homogeneous disk of mass 5 kgm rotates at the constant
rate 18 rad/s
with respect to the bent axle ABC, which
itself rotates at the constant rate 23 rad/s
about the y axis.
Determine the angular momentum C
H of the disk about its
center C.
PROBLEM 18.149
A rod of uniform cross section is used to form the shaft shown.
Denoting by m the total mass of the shaft and knowing that the
shaft rotates with a constant angular velocity , determine
(a) the angular momentum
G
H
of the shaft about its mass
center G, (b) the angle formed by H
G
and the axis AB, (c) the
angular momentum of the shaft about Point A.
PROBLEM 18.149 (Continued)
(b) Angle formed by and the axis .
G
A
BH
2
0.37927
Gmr
Hi
0.37927
G
mr
Hi 51.9
PROBLEM 18.150
A uniform rod of mass m and length 5a is bent into the shape shown and is
suspended from a wire attached at Point B. Knowing that the rod is hit at Point
A in the negative y direction and denoting the corresponding impulse by
(),Ftj determine immediately after the impact (a) the velocity of the mass
center G, (b) the angular velocity of the rod.
m 2
222
11 11 0.2
52 52
xz
I
ma ma ma
 

 
 
222
11 11 0.1
54 54
yz
I
ma ma ma
 

 
 
Angular momentum about the mass center.
222
( ) 0.35 0.3 0.2
Gx x x xy y xz z x y z
H I I I ma ma ma


222
( ) 0.3 0.66667 0.1
Gy xy x y y yz z x y z
H I I I ma ma ma


22 2
( ) 0.2 0.1 0.75
Gz xzx yzz zz x y z
H I I I ma ma ma

 
PROBLEM 18.150 (Continued)
Constraint of the supporting cable: 0
y
v
x
x
yz
ma
ijk
PROBLEM 18.151
A four-bladed airplane propeller has a mass of 160 kg and a radius of gyration of
800 mm. Knowing that the propeller rotates at 1600 rpm as the airplane is
traveling in a circular path of 600-m radius at 540 km/h, determine the magnitude
of the couple exerted by the propeller on its shaft due to the rotation of the
airplane.
PROBLEM 18.152
A 2.4-kg piece of sheet steel with dimensions 160 640 mm
was
bent to form the component shown. The component is at rest
(0)
when a couple 0(0.8 N m)Mk
is applied to it.
Determine (a) the angular acceleration of the component,
(b) the dynamic reactions at A and B immediately after the
couple is applied.
PROBLEM 18.152 (Continued)
Since the mass center lies on the rotation axis, 0
a
m


FAB a
BA