Angular Velocity after First Release

Oct 13, 2025 by pynkocean.com 134 views

Introduction

Rotational dynamics is a fundamental concept in physics that deals with the motion of objects that rotate around a central axis. In this discussion, we will explore the angular velocity of a body after sequential release from rotating arms. This problem involves the concept of rotational kinematics and the application of the principles of rotational motion.

Problem Description

Consider two arms, rigidly connected to each other, rotating around a common center point (C) with a constant angular velocity $\omega$ . A rigid body with mass $m$ and moment of inertia $I$ is attached to the end of each arm. The arms are initially rotating in the same direction, and the body is at rest. At time $t=0$ , the first arm is released, and the body begins to rotate with an initial angular velocity $\omega_1$ . At time $t=T$ , the second arm is released, and the body continues to rotate with an updated angular velocity $\omega_2$ . Our goal is to determine the angular velocity of the body after the sequential release from the rotating arms.

Mathematical Formulation

To solve this problem, we need to apply the principles of rotational kinematics and the conservation of angular momentum. The moment of inertia of the body is given by $I = \frac{1}{2}mr^2$ , where $r$ is the distance from the center of rotation to the body. The angular velocity of the body is related to the moment of inertia and the torque applied to the body by the equation:

\tau = I\alpha

where $\tau$ is the torque, $I$ is the moment of inertia, and $\alpha$ is the angular acceleration.

Angular Velocity after First Release

When the first arm is released, the body begins to rotate with an initial angular velocity $\omega_1$ . The angular velocity of the body is related to the moment of inertia and the torque applied to the body by the equation:

\omega_1 = \frac{\tau}{I}

Since the arms are rigidly connected, the torque applied to the body is equal to the torque applied to the first arm. Therefore, the angular velocity of the body after the first release is:

\omega_1 = \frac{\tau}{I} = \frac{\omega r}{r} = \omega

Angular Velocity after Second Release

When the second arm is released, the body continues to rotate with an updated angular velocity $\omega_2$ . The angular velocity of the body is related to the moment of inertia and the torque applied to the body by the equation:

\omega_2 = \frac{\tau}{I}

Since the arms are rigidly connected, the torque applied to the body is equal to the torque applied to the second arm. Therefore, the angular velocity of the body after the second release is:

\omega_2 = \frac{\tau}{I} = \frac{\omega r}{r} = \omega

Conservation of Angular Momentum

The conservation of angular momentum is a fundamental principle in physics that states that the total angular momentum of a closed system remains constant over time. In this problem, the total angular momentum of the system is the sum of the angular momentum of the body and the angular momentum of the arms. Since the arms are rigidly connected, the total angular momentum of the system is conserved.

Angular Velocity after Sequential Release

After the sequential release from the rotating arms, the angular velocity of the body is determined by the conservation of angular momentum. The total angular momentum of the system is conserved, and the angular velocity of the body is related to the moment of inertia and the torque applied to the body by the equation:

\omega = \frac{\tau}{I}

Since the arms are rigidly connected, the torque applied to the body is equal to the torque applied to the first arm. Therefore, the angular velocity of the body after the sequential release is:

\omega = \frac{\tau}{I} = \frac{\omega r}{r} = \omega

Conclusion

In this discussion, we explored the angular velocity of a body after sequential release from rotating arms. We applied the principles of rotational kinematics and the conservation of angular momentum to determine the angular velocity of the body after the sequential release. The results show that the angular velocity of the body after the sequential release is equal to the initial angular velocity of the arms.

References

[1] Goldstein, H. (1980). Classical Mechanics. Addison-Wesley.
[2] Landau, L. D., & Lifshitz, E. M. (1976). Mechanics. Pergamon Press.
[3] Marion, J. B., & Thorton, W. T. (1995). Classical Dynamics of Particles and Systems. Harcourt Brace.

Appendix

Moment of Inertia

The moment of inertia of a rigid body is given by:

I = \frac{1}{2}mr^2

where $m$ is the mass of the body and $r$ is the distance from the center of rotation to the body.

Angular Momentum

The angular momentum of a rigid body is given by:

L = I\omega

where $I$ is the moment of inertia and $\omega$ is the angular velocity.

Torque

The torque applied to a rigid body is given by:

\tau = I\alpha

Introduction

In our previous discussion, we explored the angular velocity of a body after sequential release from rotating arms. We applied the principles of rotational kinematics and the conservation of angular momentum to determine the angular velocity of the body after the sequential release. In this Q&A article, we will address some common questions related to this topic.

Q: What is the initial angular velocity of the body after the first release?

A: The initial angular velocity of the body after the first release is equal to the initial angular velocity of the arms, which is $\omega$ .

Q: How does the angular velocity of the body change after the second release?

A: The angular velocity of the body after the second release is equal to the initial angular velocity of the arms, which is $\omega$ . This is because the total angular momentum of the system is conserved, and the angular velocity of the body is related to the moment of inertia and the torque applied to the body.

Q: What is the relationship between the angular velocity of the body and the moment of inertia?

A: The angular velocity of the body is related to the moment of inertia by the equation:

\omega = \frac{\tau}{I}

where $\tau$ is the torque applied to the body and $I$ is the moment of inertia.

Q: How does the torque applied to the body affect its angular velocity?

A: The torque applied to the body affects its angular velocity by changing the rate of rotation. If the torque is increased, the angular velocity of the body will increase, and if the torque is decreased, the angular velocity of the body will decrease.

Q: What is the significance of the conservation of angular momentum in this problem?

A: The conservation of angular momentum is a fundamental principle in physics that states that the total angular momentum of a closed system remains constant over time. In this problem, the conservation of angular momentum ensures that the total angular momentum of the system is conserved, and the angular velocity of the body is related to the moment of inertia and the torque applied to the body.

Q: Can the angular velocity of the body be affected by external forces?

A: Yes, the angular velocity of the body can be affected by external forces. If an external force is applied to the body, it can change the rate of rotation and affect the angular velocity of the body.

Q: What is the relationship between the angular velocity of the body and the distance from the center of rotation?

A: The angular velocity of the body is related to the distance from the center of rotation by the equation:

\omega = \frac{\tau}{I} = \frac{\omega r}{r}

where $r$ is the distance from the center of rotation to the body.

Q: Can the angular velocity of the body be affected by the shape of the body?

A: Yes, the angular velocity of the body can be affected by the shape of the body. If the body has a non-uniform shape, its moment of inertia will be different, and the angular velocity of the body will be affected.