__Chapter # 11
(Rotation)__

**1**- A disk of radius 20 cm rotating at 42 rad/sec stops
(assume constant deceleration) after 10 sec. Through how many radians does the
disk turn during this time? 210 rad

**2**- A disk is
rotating about an axel through its center O when two forces F1 = 10 N and F2 =
15N are applied on it as shown in Fig. The moment of inertia of the disk about
O is 0.036 kg.m**2. If the system starts from rest, find the angular speed at
time = 3.0 s. [100 rad/s]

**3**- A uniform
rod of length L= 0.98 m and mass M=3.0 kg is free to rotate on a frictionless
pin through one end (See Fig). The rod has an angular speed of 4.0 rad/s when
it was in the horizontal position. What is the angular speed at its lowest
position? [6.8 rad/s]

**4**- The four
particles in Fig (6) are connected by rigid rods of negligible mass. Calculate
the moment of inertia of this system about the x axis. [63 kg.m**2]

**5**- A wheel has a moment of inertia 12 kg*m**2 about its
axis of rotation. As it turns through 5.0 rev, its angular velocity increases
from 5.0 rad/s to 6.0 rad/s. If the net torque about the axis of rotation is
constant, its value is: [2.1 N*m]

**6**- A disk has a moment of inertia 6.0 kg*m**2 about a
fixed axis of rotation. It has a constant angular acceleration of 2.0 rad/s**2.
If it starts from rest, the work done during the first 5.0 s by the net torque
on it is: [300 J]

**7**- A wheel, starting from rest, turns through 8.0
revolutions in a time interval of 17 s. Assuming constant angular acceleration,
what is the angular speed of the wheel at the end of this time interval? [5.9
rad/s]

**8**- Four
identical particles, each with mass m, are arranged in the xy plane as shown in
figure. They are connected by light rods to form a rigid body. If m=2.0 kg and
a=1.0 m, the moment of inertia of this system about the y-axis is: [12 kg*m**2]

** **

**9**- A wheel
with a moment of inertia of 5.0 kg*m**2 and a radius of 0.25 m rotates about a
fixed axis perpendicular to the wheel and through its center as shown in figure
10. A force of 2.0 N is applied tangentially to the rim. As the wheel rotates
through one revolution, what is the work done by the force ? [3.14 J]