physics : class11 Moment about an Axis : Moment of a Force : Motion of System of Particles and Rigid Body MCQ Questions and Answers
Practice important
Moment about an Axis
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. The moment of a force about a specified axis is the component of the torque along which direction?
A.
Along the specified axis
B.
Perpendicular to the specified axis only
C.
Along the direction of the force only
D.
Along the direction of displacement only
Correct Answer:
Along the specified axis
Explanation:
The moment of a force about an axis is the component of the torque vector along that axis.
2. A force acts along a line that passes through a fixed axis. What is its moment about that axis?
A.
Maximum
B.
Zero
C.
Equal to the force
D.
Equal to the distance from the axis
Correct Answer:
Zero
Explanation:
When the line of action of a force passes through the axis, the perpendicular distance is zero, so the moment about the axis is zero.
3. The SI unit of moment of a force about an axis is:
A.
N
B.
N m
C.
J/s
D.
kg m/s
Correct Answer:
N m
Explanation:
Moment about an axis is force multiplied by perpendicular distance, so its SI unit is newton metre (N m).
4. For a force acting perpendicular to a radial line from an axis, the magnitude of its moment about the axis is:
A.
F divided by r
B.
r divided by F
C.
Fr
D.
F plus r
Correct Answer:
Fr
Explanation:
The moment magnitude is force multiplied by the perpendicular distance from the axis to the line of action. Here that distance is r, giving Fr.
5. If the perpendicular distance of a force from an axis is doubled while the force remains unchanged, its moment about the axis becomes:
A.
Half
B.
Unchanged
C.
Double
D.
Four times
Correct Answer:
Double
Explanation:
Moment about an axis equals force times perpendicular distance. Doubling the distance doubles the moment.
6. A force of 5 N acts with a perpendicular distance of 2 m from an axis. What is its moment about the axis?
A.
2.5 N m
B.
7 N m
C.
10 N m
D.
25 N m
Correct Answer:
10 N m
Explanation:
The moment is F multiplied by the perpendicular distance: 5 N × 2 m = 10 N m.
7. Which force produces the greatest moment about an axis when all forces have the same magnitude?
A.
The force whose line of action is closest to the axis
B.
The force whose line of action passes through the axis
C.
The force whose line of action has the greatest perpendicular distance from the axis
D.
The force directed toward the axis
Correct Answer:
The force whose line of action has the greatest perpendicular distance from the axis
Explanation:
For equal forces, the moment is greatest when the perpendicular distance from the axis to the line of action is greatest.
8. The moment of a force about an axis is zero when the force is directed:
A.
Tangentially at a large distance from the axis
B.
Along a line passing through the axis
C.
Perpendicular to the axis at a nonzero distance
D.
At an angle of 90 degrees to the radial line
Correct Answer:
Along a line passing through the axis
Explanation:
A force whose line of action passes through the axis has zero perpendicular distance and therefore zero moment about that axis.
9. If the component of torque along a chosen axis is 8 N m, the moment of the force about that axis is:
A.
4 N m
B.
8 N m
C.
16 N m
D.
Zero
Correct Answer:
8 N m
Explanation:
The moment about an axis is defined as the component of the torque along that axis, so it is 8 N m.
10. A force of 10 N acts at a perpendicular distance of 0.5 m from an axis. Its moment about the axis is:
A.
0.05 N m
B.
5 N m
C.
10.5 N m
D.
20 N m
Correct Answer:
5 N m
Explanation:
Using moment = force × perpendicular distance, the moment is 10 N × 0.5 m = 5 N m.
Short Questions and Answers
Practice short questions and answers related to
Moment about an Axis
.
Short questions are currently unavailable for this page.