# Dynamics: Practice #2 Kinematics &amp; Kinetics of Rigid Bodies

```Dynamics: Practice #2 Kinematics &amp; Kinetics of Rigid Bodies
1.
Determine the acceleration of the cylinder. The tension in the rope is 12 N. The
cylinder has a mass of 4 kg, and a radius of 0.02 m. Assume the cylinder does not
slip as it rolls.
2.
At the instant shown, the 20-lb bar is rotating downwards at
2 rad/s. The spring attached to its end always remains
vertical due to the roller guide at C. If the spring has an
unstretched length of 4 ft and a stiffness of k=3 lb/ft,
determine the angular velocity of the bar the instant it has
rotated downward 30 degrees below the horizontal.
3.
A thin rod of mass 2kg and length l=1.5 m has an angular
velocity ω0 = 4 rad/s while rotating on a smooth surface.
Determine its new angular velocity just after its end
strikes and hooks onto the peg and the rod starts to rotate
4.
At a given instant, the slider block B is traveling to the right
with the velocity and acceleration shown. Determine the
angular velocity and acceleration of the wheel at this
instant. The radius of the wheel is 5 inches.
5.
Gear A has a mass of 60 kg and a radius of gyration kC=160mm. If a
motor supplies a torque having a magnitude M=(1.2t) N*m, where t is
in seconds, to gear A, determine the angular velocity of gear A in 3 s.
Initially, gear A is rotating at ω1=2 rad/s.
R. Gist (Sum. ’06)
1 of 2
Ver. B, Rev. 2
Dynamics: Practice #2 Kinematics &amp; Kinetics of Rigid Bodies
6.
The elevator car E has a mass of 1.80 Mg and the counterweight C has a mass of
2.30 Mg. If a motor turns the driving sheave A with a torque of M=15 N*m, where θ
is in radians, determine the speed of the elevator when it has ascended 14 m starting
from rest. Each sheave A and B has a mass of 150 kg and a radius of gyration of
k=0.2 m about its mass center or pinned axis. Neglect the mass of the cable and
assume the cable does not slip on the sheaves.
7.
The vertical-axis windmill consists of two blades that have a parabolic shape. If
the blades are originally at rest and begin to turn with a constant angular
acceleration of αe = 0.5 rad/s2, determine the magnitude of the velocity and
acceleration of point A on the blade after the blade has rotated through two
revolutions.
R. Gist (Sum. ’06)
2 of 2
Ver. B, Rev. 2
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