A man, mass M, stands on a massless rod which is free to rotate about its center in the horizontal plane. The man has a gun (massless) with one bullet, mass m. He shoots the bullet with velocity vB, horizontally. Find the angular velocity of the man as a function of the angle, 0, which the bullet's velocity vector makes with the rod. side view top view
Angular Momentum
The momentum of an object is given by multiplying its mass and velocity. Momentum is a property of any object that moves with mass. The only difference between angular momentum and linear momentum is that angular momentum deals with moving or spinning objects. A moving particle's linear momentum can be thought of as a measure of its linear motion. The force is proportional to the rate of change of linear momentum. Angular momentum is always directly proportional to mass. In rotational motion, the concept of angular momentum is often used. Since it is a conserved quantity—the total angular momentum of a closed system remains constant—it is a significant quantity in physics. To understand the concept of angular momentum first we need to understand a rigid body and its movement, a position vector that is used to specify the position of particles in space. A rigid body possesses motion it may be linear or rotational. Rotational motion plays important role in angular momentum.
Moment of a Force
The idea of moments is an important concept in physics. It arises from the fact that distance often plays an important part in the interaction of, or in determining the impact of forces on bodies. Moments are often described by their order [first, second, or higher order] based on the power to which the distance has to be raised to understand the phenomenon. Of particular note are the second-order moment of mass (Moment of Inertia) and moments of force.
![**Title: Angular Motion of a Man on a Rotatable Rod**
**Problem Description:**
A man with mass \( M \) stands on a massless rod, which can rotate freely about its center in the horizontal plane. The man is holding a gun (considered massless) with one bullet of mass \( m \). He fires the bullet with a horizontal velocity \( v_B \). We are tasked with finding the angular velocity of the man as a function of the angle \( \theta \), which the bullet’s velocity vector makes with the rod.
**Diagram Explanation:**
- **Side View:**
Illustrates the man standing on the rod, positioned halfway along its length (\(\frac{l}{2}\)).
- **Top View:**
Shows the bullet being fired at an angle \(\theta\) relative to the rod. The bullet's trajectory forms an angle with the horizontal axis of the rod.
**Objective:**
Determine the angular velocity of the man as a function of the angle \(\theta\).
**Analysis Approach:**
1. **Conservation of Angular Momentum:**
- Before firing, the system’s angular momentum should be zero since both the man and the gun are at rest relative to the rod.
- Upon firing the bullet, the momentum imparted will cause both linear and angular motion.
2. **Component Resolution:**
- Analyze the components of the bullet’s velocity:
- Radial Component (\(v_{B \, \text{radial}} = v_B \cos(\theta)\))
- Tangential Component (\(v_{B \, \text{tangent}} = v_B \sin(\theta)\))
3. **Calculate Angular Velocity:**
- Utilize the tangential component to establish the effect on rotational motion.
- Use the conservation principles to express the angular velocity of the man in terms of angular displacement \(\theta\).
This problem involves understanding basic physical principles such as conservation laws and rotational dynamics to solve for angular velocity as a function of changing angles in a physical system.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F4776c488-bd56-43d7-a281-357c0247fbc6%2F0056acf9-69a9-441b-bee7-c57ca0ec0a83%2Fwfwit3h_processed.png&w=3840&q=75)
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