Lab Section: ______
Name: ______________________________
Lab Instructor: ______________________________
Grade: ______
P1112 Lab Notes
Prelab 81
Cornell University, Spring 2009
Lab Unit # 8 Prelab Questions:
Angular Momentum & Precession
1.
Write the general mathematical relation that exists between the total (vector) angular momentum
L
r
of
a system about a point and the net external (vector) torque
τ
r
acting on the system about the same
point.
2.
A spinning bicycle wheel of total mass
M
and radius
R
is suspended
from a rope at point P on its axle, a distance
s
from the wheel’s
center of mass (CM).
(a)
Write an expression for the magnitude of the torque
τ
about
point P produced by the wheel’s weight (in terms of
M
and
s
).
=
τ
____________________.
What is the direction of this torque
τ
r
as a vector quantity?
(b)
What torque about point P is produced by the tension force exerted by the rope?
=
tension
τ
r
____________________.
(c)
With the wheel spinning as shown in the diagram, which way will it
precess
about point P?
Please be sure to express your answer
unambiguously
by specifying your vantage point
carefully.
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 Spring '07
 LECLAIR,A
 Angular Momentum, Momentum, Cornell University, spin angular speed

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