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PROBLEM 17.20
A 160-lb gymnast is executing a series of full-circle swings on
the horizontal bar. In the position shown he has a small and
negligible clockwise angular velocity and will maintain his
body straight and rigid as he swings downward. Assuming that
during the swing the centroidal radius of gyration of his body is
1.5 ft, determine his angular velocity and the force exerted on
his hands after he has rotated through (a) 90°, (b) 180°.
PROBLEM 17.20 (Continued)
PROBLEM 17.21
A collar with a mass of 1 kg is rigidly attached at a distance
d 300 mm from the end of a uniform slender rod AB. The rod has
a mass of 3 kg and is of length L 600 mm. Knowing that the rod
is released from rest in the position shown, determine the angular
velocity of the rod after it has rotated through 90°.
PROBLEM 17.22
A collar with a mass of 1 kg is rigidly attached to a slender rod AB
of mass 3 kg and length L 600 mm. The rod is released from rest
in the position shown. Determine the distance d for which the
angular velocity of the rod is maximum after it has rotated 90°.
PROBLEM 17.22 (Continued)
PROBLEM 17.23
Two identical slender rods AB and BC are welded together to form
an L-shaped assembly. The assembly is pressed against a spring at
D and released from the position shown. Knowing that the
maximum angle of rotation of the assembly in its subsequent
motion is 90° counterclockwise, determine the magnitude of the
angular velocity of the assembly as it passes through the position
where rod AB forms an angle of 30° with the horizontal.
PROBLEM 17.24
The 30-kg turbine disk has a centroidal radius of gyration of 175 mm and
is rotating clockwise at a constant rate of 60 rpm when a small blade of
weight 0.5 N at Point A becomes loose and is thrown off. Neglecting
friction, determine the change in the angular velocity of the turbine disk
after it has rotated through (a) 90°, (b) 270°.
PROBLEM 17.24 (Continued)
PROBLEM 17.25
A rope is wrapped around a cylinder of radius r and mass m as shown. Knowing that
the cylinder is released from rest, determine the velocity of the center of the cylinder
after it has moved downward a distance s.
PROBLEM 17.26
Solve Problem 17.25, assuming that the cylinder is replaced by a thin-walled pipe of
radius r and mass m.
PROBLEM 17.25
A rope is wrapped around a cylinder of radius r and mass m as
shown. Knowing that the cylinder is released from rest, determine the velocity of the
center of the cylinder after it has moved downward a distance s.
