Problem 19.? During extravehicular activity, an astro-
naut’s angular velocity is initially zero. She activates two
thrusters of her maneuvering unit, exerting equal and
opposite forces T = 2 N. The moment of inertia of the
astronaut and her equipment abo

Problem 19.5 The helicopter’s rotor starts ﬁ‘om rest.
Suppose that its engine exerts a constant 1 62? N-m cou-
ple on the rotor and aerodynamic drag is negligible. The
rotor’s moment of inertia is I = 542 kg—mz.
(a) Use work and energy to determine the ma

Problem 19.3 The 8-kg slender bar is released from
rest in the horizontal position 1 and falls to position 2. p—g III—.4
(a) How much work is done by the bar’s weight as it 1
falls from position 1 to position 2?
(b) How much work is done by the force exer

Problem 19.6 The helicopter’s rotor starts ﬁ‘om rest.
The moment exerted on it (in N-m) is given as a function
of the angle through which it has turned in radians by
M = 6500— 206. The rotor’s moment of inertia is I =
540 kg-mz. Determine the rotor’s angu

Problem 19.4 The space station is initially not rotat-
ing. Its reaction control system exerts a constant couple
on it until it has rotated 90°, then exerts a constant couple
of the same magnitude in the opposite direction so that
its angular velocity has

Problem 19.11 The object consists of an 35.6 N slen-
der bar welded to a 53.4 N circular disk The object is 559mm
released from rest in position 1. Determine the x and y 12? _
components of force exerted on the object by the pin .r \
support when it is in

Problem 19.10 The object consists of an 35.6 N slender
bar welded to a circular disk. TWhen the object is released
ﬂom rest in position 1, its angular velocity in position 2 12? ,_ _H
is 4.6 rad-ls. What is the weight of the disk?I (“K \‘
1i
Salutiﬂn:

Problem 19.9 The ZO-N bar is released ﬂom rest in the
horizontal position 1 and falls to position 2. In addition
to the force exerted on it by its weight, it is subjected to a
constant counterclockwise couple M = 30 N-In. Deter-
mine the bar’ s counterclo

Problem 19.3 The 20-kg disk is at rest when the
constant 10 N-m counterclockwise couple is applied.
Determine the disk’s angular velocity (in rpm) when
it has rotated through four revolutions (a) by applying
the equation of angular motion BM :13, and (b)

Problem 19.1 The moment of inertia of the rotor of
the medical centrifuge is I = 0.2 kg-mE. The rotor starts
from rest and the motor exerts a constant torque of
0.8 N-m on it.
(a) How much work has the motor done on the rotor
when the rotor has rotated th

Problem 19.2 Thel?.8 N slender baris 0.61m in length. 3)
It started from rest in an initial position relative to the
inertial reference frame. When it is in the position shown,
the velocity of the end A is 6.?li + 4.2?j (mfs) and the
bar has a countercloc