(a)
The angular momentum of the assembly about point
Answer to Problem 18.15P
The angular momentum of the assembly about point
Explanation of Solution
Given information:
The mass of each L-shaped arm is
The below figure represents x’, y’, and z’ axis parallel to the x, y, and z axis.
Figure (1)
Write the expression for angular velocity in x’-direction.
Write the expression for angular velocity in y’-direction.
Write the expression for mass of each segment of arm
Here,
Write the expression for angular velocity in z-direction.
Here, speed of assembly is
Write the expression for moment of inertia for part (1) in x-z direction
Here mass moment of inertia along x-y direction is
Write the expression for moment of inertia for part (1) in y-z direction.
Here mass moment of inertia along y-z direction is
Write the expression for moment of inertia for part (1) in z direction
Here mass moment of inertia along z direction is
Write the expression for moment of inertia for part (2) in x-z direction.
Here, mass moment of inertia along x-y direction is
Write the expression for moment of inertia for part (2) in y-z direction.
Here mass moment of inertia along y-z direction is
Write the expression for moment of inertia for part (2) in z direction.
Here mass moment of inertia along z direction is
Write the expression for moment of inertia for part (3) in x-z direction.
Here, mass moment of inertia along x-z direction is
Write the expression for moment of inertia for part (3) in y-z direction.
Here, mass moment of inertia along y-z direction is
Write the expression for moment of inertia for part (3) in z direction.
Here mass moment of inertia along z direction is
Write the expression for moment of inertia for part (4) x-z direction.
Here, mass moment of inertia along x-y direction is
Write the expression for moment of inertia for part (4) y-z direction.
Here, mass moment of inertia along y-z direction is
Write the expression for moment of inertia for part (4) z direction.
Here mass moment of inertia along z direction is
Write the expression for total mass moment of inertia in x-y direction.
Write the expression for total mass moment of inertia in y-z direction.
Write the expression for total mass moment of inertia in z direction.
Substitute
Substitute
Substitute
Write the expression for angular momentum in x-z direction.
Substitute
Write the expression for angular momentum in y-z direction.
Substitute
Write the expression for angular momentum in z direction.
Substitute
Write the expression for
Substitute,
Calculation:
Substitute
Substitute
Substitute
Substitute
Substitute
Conclusion:
Thus angular momentum of the assembly about point
(b)
The angle formed by
Answer to Problem 18.15P
The angle formed by
Explanation of Solution
Given information Write the expression for the magnitude of angular momentum in about assembly A
Write the Expression for angle formed by
Calculation:
Substitute
Substitute
Conclusion:
Thus angle formed by
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Chapter 18 Solutions
Vector Mechanics For Engineers
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