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PROBLEM 17.58
Disk A, of weight 5 lb and radius 3in.,r is at rest when it is placed in
contact with a belt which moves at a constant speed 50 ft/s.v Knowing that
0.20
k
between the disk and the belt, determine the time required for the
disk to reach a constant angular velocity.
PROBLEM 17.59
A cylinder of radius r and weight W with an initial counterclockwise angular
velocity
0
is placed in the corner formed by the floor and a vertical wall.
Denoting by
k
the coefficient of kinetic friction between the cylinder and the
wall and the floor derive an expression for the time required for the cylinder to
come to rest.
PROBLEM 17.60
Each of the double pulleys shown has a centroidal mass moment of inertia
of 0.25
2
kg m ,
an inner radius of 100 mm, and an outer radius of 150
mm. Neglecting bearing friction, determine (a) the velocity of the cylinder
3 s after the system is released from rest, (b) the tension in the cord
connecting the pulleys.
PROBLEM 17.60 (Continued)
PROBLEM 17.61
Each of the gears A and B has a mass of 675 g and has a radius of
gyration of 40 mm, while gear C has a mass of 3.6 kg and has a
radius of gyration of 100 mm. Assume that kinetic friction in the
bearings of gears A, B, and C produces couples of constant magnitude
0.15 N m,
0.15 N m,
and 0.3 N m,
respectively. Knowing that the
initial angular velocity of gear C is 2000 rpm, determine the time
required for the system to come to rest.
PROBLEM 17.61 (Continued)
PROBLEM 17.62
Disk B has an initial angular velocity
0
when it is brought into contact
with disk A which is at rest. Show that the final angular velocity of disk B
depends only on
0
and the ratio of the masses
A
m
and
B
m
of the two
disks.
PROBLEM 17.63
The 7.5-lb disk A has a radius
6
A
r
in. and is initially at rest. The
10-lb disk B has a radius
8
B
r
in. and an angular velocity
0
of 900
rpm when it is brought into contact with disk A. Neglecting friction in
the bearings, determine (a) the final angular velocity of each disk,
(b) the total impulse of the friction force exerted on disk A.
PROBLEM 17.63 (Continued)
PROBLEM 17.64
A tape moves over the two drums shown. Drum A weighs 1.4 lb and has
a radius of gyration of 0.75 in., while drum B weighs 3.5 lb and has a
radius of gyration of 1.25 in. In the lower portion of the tape the tension
is constant and equal to
0.75
A
T
lb. Knowing that the tape is initially at
rest, determine (a) the required constant tension T
B
if the velocity of the
tape is to be
10v
ft/s after 0.24 s, (b) the corresponding tension in the
portion of tape between the drums.
