Assignment MasteringPhysics: Print View
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20 - Textbook problems for Moment of Inertia and Torque
Due: 8:00pm on Wednesday, April 4, 2012
Note: To understand how points are awarded, read your instructor's Grading Policy.
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Hint to Problem 9.34: Since the rods are light and the balls are small, the system effectively consists of four point-like objects.
Exercise 9.34
Four small spheres, each of which you can regard as a point of mass 0.200
, are arranged in a square 0.400
on a side and connected by light rods .
Part A
Find the moment of inertia of the system about an axis through the center of the square, perpendicular to its plane (an axis through point O in the figure).
ANSWER:
2
= 6.4010
Correct
Part B
Find the moment of inertia of the system about an axis bisecting two opposite sides of the square (an axis along the line AB in the figure).
ANSWER:
2
= 3.2010
Correct
Part C
Find the moment of inertia of the system about an axis that passes through the centers of the upper left and lower right spheres and through point O.
ANSWER:
2
= 3.2010
Correct
Hint to Problem 9.37 Part C: Since the bar is thin and the balls are small, is there any distance from the axis to any element of mass?
Exercise 9.37
A uniform bar has two small balls glued to its ends. The bar is 2.00
long and with mass 4.00
, while the balls each have mass 0.500
and can be
treated as point masses.
Part A
Find the moment of inertia of this combination about an axis perpendicular to the bar through its center.
ANSWER:
= 2.33
Correct
Part B
Find the moment of inertia of this combination about an axis perpendicular the to bar through one of the balls.
ANSWER:
= 7.33
Correct
Part C
Find the moment of inertia of this combination about an axis parallel to the bar through both balls.
ANSWER:
=0
Correct
Part D
Find the moment of inertia of this combination about an axis parallel to the bar and 0.500 m from it.
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MasteringPhysics: Assignment Print View
ANSWER:
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= 1.25
Correct
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Hint to Problem 9.54: Use the Parallel-Axis Theorem.
Exercise 9.54
Part A
Find the moment of inertia of a hoop (a thin-walled, hollow ring) with mass
Express your answer in terms of the variables
ANSWER:
and
and radius
about an axis perpendicular to the hoop's plane at an edge.
.
=
Correct
Exercise 10.3
A square metal plate 0.180
on each side is pivoted about an axis through point
at its center and perpendicular to the plate .
Part A
Calculate the net torque about this axis due to the three forces shown in the figure if the magnitudes of the forces are
= 16.7
= 18.0
,
= 14.0
, and
. The plate and all forces are in the plane of the page. Take positive torques to be counterclockwise.
ANSWER:
= 1.77
Correct
Exercise 10.2
Part A
Calculate the net torque about point
for the two forces applied as in the figure . The rod and both forces are in the plane of the page. Take positive
torques to be counterclockwise.
ANSWER:
= -28.0
Correct
Score Summary:
Your score on this assignment is 96.5%.
You received 43.42 out of a possible total of 45 points.
http://session.masteringphysics.com/myct/assignmentPrintView?assignmentID=1738202
4/27/2012